3rd International Symposium on Mine Safety Science and Engineering

Preface

Editorial Staff — 2016-11-28

Preface

Mathematical model for gas diffusion from non-homogeneous coal particles

Yanwei Liu — 2016-11-28

By establishing model and experimental verification, this paper aims at improving the accuracy and applicability of gas diffusion mathematical model from coal particles in engineering applications. Firstly, based on Fick's second law and the continuity theory of gas diffusion in porous media, a new constitutive model for gas diffusion from non-homogeneous coal particles with three-layer pore structure is constructed by considering the difference of characteristics in pore structure between soft coal and hard coal. Then, the analytical solution is derived from the new model, that is, the quantitative relationship between gas diffusion rate (Q_t/Q_∞) and diffusion time (t). The pore structure parameters of soft coal and hard coal from Juji coal mine were determined by using the mercury injection method. Gas desorption and diffusion rules of coal samples are numerically calculated and investigated by using physical simulation methods. Lastly, the applicability of the constitutive model was verified. The research results show that the homogeneous model widely used only applies to describe gas diffusion process of the hard coal within the initial 10minutes, while the new model can describe the gas diffusion law of different pore structure characteristics. The calculation results from the new model and the physical experimental results are nearly identical within the initial 30 minutes. The difference of gas diffusion process between soft coal and hard coal can be effectively reflected by the parameters of pore structure in the new model.

Permeability prediction for coal reservoirs and reconstruction of a different scales pore-fractures network

Xiaoming Ni — 2016-11-28

Fine describing the connectivity of different scaled pore-fractures and quantitatively expressing permeability can provide an important basis for the output degree of the gas. Different scales pore-fractures network was reconstructed by observing large number of coal samples and software simulation of Monte Carlo method. Seepage model about different scales pore-fractures network was established by assigning zero method and using MatLab software. Effect permeability about different scales pore-fractures network was obtained by two-dimensional seepage equation. Predicting permeability results is compared with the measured permeability results, the results showed that: the dominant order of different scales pore-fractures connected path from high to low is millimeters fractures, seepage pores and micron-sized fractures. The contribution of coal reservoir permeability from big to small is millimeters fractures, micron-sized fractures and seepage pores. Different parameters in different scales pore-fractures are of different influences to permeability. Reconstruction of different scales pore-fractures network can clearly display the connectivity of pore-fractures, which can provide a basis for selecting migration path and studying flowing pattern about gas.

Quantitative risk assessment on large-scale oil depots of opencast coal mine

Ru Jun Wang — 2016-11-28

In recent years, there are many large-scale oil depots have been built in the opencast coal mine in China. In order to prevent and control the major accidents of the opencast mine, it is significant to assess the risk of the large-scale oil depots. This paper is aiming at bring about a quantitative risk assessment (QRA) method to assess the fire risk of opencast coal mine. Firstly, the risk analysis of large-scale oil depots for coal mine were made, the hazardous characters of gasoline and diesel were described and the risk consequences were discussed. And then, it is pointed that pool fire is the best typical and serious consequence, the mathematical model of pool fire was introduced. Furthermore, the quantitative risk assessment (QRA) method was developed to assess the fire risk of the large-scale oil depots. Also, the QRA method was applied to assess the risk of a selected large-scale oil depot in a large opencast coal mine in China based on the QRA software CASSTQRA. For the gasoline tank of 1´104 m3, the death, serious injury and light injury affected radius of a pool fire were 64.75m, 75.66m and 106.86m and the individual risk was acceptable. Finally, some suggestions were proposed to improve the safety of the large-scale oil depots. The study is helpful to the safety management and prevention of major accident of opencast coal mine.

Development and realization of a coal and gas outburst simulation device

Baisheng Nie — 2016-11-28

Similar coal and gas outburst simulation devices both at home and abroad are analyzed and the advantages and disadvantages of them are gained. A large size experimental device of coal and gas outburst simulation is developed based on the congeneric testing device. This device consist of coal and gas outburst model system, gas injection system, loading system, stress measurement system, gas pressure measurement system, temperature measurement system, electromagnetic radiation testing system and high-speed photography system. The functions of the device are as following. (1) To study laws of roof break development and stress evolution during outburst process by simulating coal seam, roof and floor with similar material. (2)To simulate stress distribution of roof at high strength springs of different sizes. (3)To realize the uniform adsorption in coal by 3 gas injection pipes that pre-buried. (4) To induce coal and gas outburst at predetermined gas pressure by blasting bursting disc instantly that set on the outburst hole. (5) To observe and record fracture and migration process of coal in the cavity during outburst that is achieved by a visual glass window on the side of cavity

The distribution and origin of hydrogen sulfide abnormal enrichment coal mines in China

Qigen Deng — 2016-11-28

Coal mines that contain hydrogen sulfide (H₂S) are widely distributed in China, at present they are mainly located in Zaozhuang in east China, Xin'an, Anyang and Shuangfeng in central China. Qinshui basin, Taiyuan - Liulin areas and Wuhai in north China, Tongchuan-Xianyang area in northwestern China as well as places such as Shizuishan, Houdon, Changji, Liuhuanggou and Sikeshu which belong to Xinjiang, mainly in northwest China, and showed a rapid increase. The contents of H₂S in coal mines changed greatly, from 10 ppm to 5000 ppm. The abnormal coal seams are mainly distributed in the Permian Longtan Formation of southwest China, Permian Shanxi Formation and Carboniferous Taiyuan Formation of east, north and central China, Jurassic Xishanyao and Yan'an Formation of northwest China and so on. The abnormal area have a favorable overlying strata, the hydraulic connection between the underground water and other aquifers are weak, so they are good thick reservoir-seal combination which are beneficial to the origin of Bacterial Sulfate Reduction (BSR) or Thermochemical Sulfate Reduction (TSR). The main origin of H₂S in coal mines are BSR or TSR, and the origin model can be identified synthetically via the tectonic evolution, coal thermal evolution history, isotopic characteristics of carbon and sulfur, methane gas component testing, sulfate sources and sulfate-reducing bacteria activity features.

Accumulation pattern of groundwater containing Hydrogen Sulfide in the southern Junggar basin in China

Qigen Deng — 2016-11-28

The surface water and groundwater flows from south to north to the interior basin in the midst of southern Junggar basin of China. The thick and loose gravel sand layer ware accumulated in the region, tectonic depressions of echelon arranged, tectonic depression or basement uplift, under the control of hydrodynamic block gas, provides a huge space of occurrence and migration for groundwater (Hydrogen Sulfide). The water rich sulfate and chloride, runoff along the direction, dissolution and leaching may occur in the infiltration and runoff process, under intense evaporation, the water of high Salinity may form of HCO₃-Ca-Na, HCO₃-SO₄-Na-Ca, Cl•SO₄-Na and HCO₃-SO₄-Cl-Na-K. The water rich SO₄^2-、Cl^-、Ca²⁺、Mg²⁺and Na⁺ through the zone of hydrocarbon-rich (ΣCH, C), in the role of geothermal warming, under suitable geological conditions, the BSR or TSR may happen and the H₂S can generating, resulting concentration of calcium significantly lower and rich in hydrogen sulfide in water.

Application research on gas drainage technology at low permeability coal seam

Shengchu Huang — 2016-11-28

Gas drainage at low gas permeability coal seam is a main barrier affecting safety and efficient production in coal mines. Therefore, the research and application of drainage technology in low gas permeability coal seam is a key technical for coal mine gas control. In order to improve the drainage effect, this paper studies the changes of original stress field, displacement field, gas pressure field and gas movement field inside the overburden rock around the goaf, and establishes a three-dimensional solid-gas-liquid coupling numerical model. Then the numerical simulation analysis for regularity under condition of coupling of released rock and fluid are conducted. This paper comprehensively analyzes the stress and fissure variation regularity during coal extraction in deep mines, as well as the scope of released gas movement, enrichment range and movement regularity during coal mining. It can provide reference for prediction of gas emission from deep coal seam mining, and help to design efficient coal mine gas drainage. Yangquan mine area is chosen as the research target, and the gas movement regularity and emission characteristics are studied. Then the gas drainage technology and parameters for the current coal seam are studied. After measuring the gas drainage amount in-situ, it was found that the technology can achieve notable drainage results, gas drainage rate increase by 30%~40%, for low permeability coal seam.

Influence of temperature on gas desorption-diffusion laws of coal particles

Linchao Dai — 2016-11-28

With the continuous increase of coal mining depth in China, the temperature has more and more apparent effect on the coal seam gas adsorption, desorption-diffusion, seepage, et al. To further investigate the effect of temperature on the gas desorption and flow law of coal, the coal gas desorption test system by independent research and development was used and the gas desorption diffusion process of coal particles was experimental study under the conditions of adsorption equilibrium pressure 1.1MPa and desorption temperature (20℃,30℃and 40℃). The variation law of the coal particles gas desorption diffusion amount and the gas desorption diffusion rate change with temperature were defined. Then the mathematical physics equations of coal particle gas desorption diffusion was established based on the third boundary condition, and the desorption diffusion coefficient was solved by using the piecewise fitting method combined with the dynamic process characteristic of gas desorption diffusion and the experimental data. The variation law of the gas diffusion coefficient change with temperature was got. The results show that: (1) the cumulative amount of coal particles gas diffusion desorption is a capped monotonically increasing function. And the higher the temperature, the faster the initial rate of gas desorption diffusion. (2)In the short time (t<10min), the gas desorption diffusion coefficient decreases as the temperature increases, and when t>10min, the temperature changes has little effect on the desorption-diffusion coefficient. It mainly because the rise of temperature accelerates the gas molecules velocity, it increases the collisions probability between the gas molecules, and the diffusion length of gas molecules becomes smaller, then the effective diffusion cross-sectional area decreases, at last the gas desorption diffusion coefficient reduces. It provides theoretical guidance for the prevention of coal and gas outburst, prediction of gas emission quantity and gas extraction, etc.

Numerical simulation of gas migration tule in mining-induced fractures field

Jie Cao — 2016-11-28

Gas extraction practice has proved that the vast majority of the mining area in China is unfavorable use gas drainage technology such as ground drilling hole, and should use the mining-induced fractures for gas extraction. Therefore, research the gas migration rule in mining-induced fractures field above the goaf, can provide a technical support for optimizing system arrangement of pressure-relieved gas extraction, and increasing the rate of gas extraction.

At present, scholars by utilizing numerical simulation to study the gas migration rule in working face and goaf without considering the influence of the mining-induced fractures, and there have not a better simulation software which can simulate not only the space-time evolution of the mining-induced fractures field, but also the rule of gas migration. This study takes one mining face of 10th mine in Pingdingshan Coalmine Group in Henan China as the research background. Firstly establishes numerical calculation model, and uses UDEC software to calculate the evolution formation of the mining-induced fracture field. And then gets the spatial diagram by image processing method, imports it into COMSOL MULTIPHYSICS software to simulate the process of gas migration.

By combining the UDCE and COMSOL software, the gas migration rule in mining-induced fractures above goaf is numerically simulated, and the results are shown as follows: When the working face advances to a certain distance, goaf overburden gradually form a mining-induced fractures trapezoid table, and with the working face advancing, the height of the mining-induced fractures trapezoid table increased; Compare with the gas migration in the overburden matrix, the gas flow in abscission layer crack and vertical fracture of mining-induced fractures is directional, the gas enrichment area is located in the biggest abscission layer crack area in upper end of mining-induced fractures trapezoid table; When drilling for gas extraction in mining-induced fracture field, the gas concentration declines in the whole region during the process of gas drainage, and the rate of gas concentration decline faster in fractured zone, it is shown that with the gas drainage, the velocity of the gas flow in the mining-induced fracture is faster.

Methods of measuring the effective drainage radius of 3# coal seam in Huoerxinhe coal mine

Linchao Dai — 2016-11-28

At present, the theoretical calculation method, the in-situ test method and numerical simulation method are used to determine the radius of coal seam gas drainage. Determining a reasonable gas drainage radius parameter has important practical significance to improve drainage effect and eliminate the outburst danger quickly.

In order to determine the gas drainage parameters of Huoerxinhe 3# coal seam reasonably and eliminate the prominent risk of mining face quickly and efficiently, the current embarrassment of determining the gas drainage radius was analyzed. Based on the own gas and geological conditions of Huoerxinhe 3# coal seam, the theoretical calculations, laboratory parameters measured and site measurement were used to investigate the effective drainage radius of Huoerxinhe 3# coal seam.

The results show that the site measurement of gas drainage radius has greater difficult in testing, worse precision and other issues. But it can obtain the exact value of effective drainage radius by combining theoretical calculation method with the in-situ test method. The effective drainage radius of Huoerxinhe 3# coal seam is 1.6m by using this method. It can provide the basis for gas drainage borehole design, raise the gas drainage efficiency and ensure the mining safely. Simultaneously, this method in this paper can be used as a general method to determine effective drainage radius.

Temperature variation of coal during the gas adsorption process

Tao Yang — 2016-11-28

Using self-made coal gas adsorption-desorption instrument, a test research on temperature variations of adsorption process under different conditions was made in the laboratory to study adsorption law of coal gas and to reveal coal gas adsorption mechanism. Under the same conditions, the order of unit mass of coal’s gas adsorption and the temperature variation is: Zhenxing 2# Coal> Runhong 3# coal> Malan 8# coal. The experimental results also showed that the gas adsorption get lower as the temperature was getting higher. For the same coal sample under the same condition, the smaller of particle size, the greater pressure variations of methane adsorption process and the larger gas adsorption in same period. The research result of this paper is significant meaningful to reveal the mechanism of coal and gas outburst.

Statistical analysis of coal mine accidents in China from 2005-2013

Xinsheng Hu — 2016-11-28

Filing up and categorizing coal mine accidents during 2005-2013 within china by mathematical statistics. Focusing the aspects such as accident types, occurrence time, geographical distribution, and death rate per million tons, analyzing the characteristics of coal mine accidents, and as well as summarizing the coal mine accident potential regularity. And then, it can be proposed the technical prevention means and safety management measures to prevent and reduce coal mine accidents scientifically and effectively. According to the accident categories, it can be analyzed that the number of roof accident and death are the most and the average mortality of fire accident are the highest. According to the months, the curve of accident is in line with the curve of death toll and both show fluctuation. February is the lowest, which is closely related to low temperature. According to the 27 provincial units, death toll of Guizhou, Sichuan, Hunan, Shanxi, Chongqing coal mine accident is relatively more. China should strengthen the supervision of these places.

Analysis of coal crack and permeability characteristics slotted by water jet and the effect on gas outburst

Chunming Shen — 2016-11-28

Water jet slotting technology is an effective method of increasing coal permeability, improving gas extraction quantity and prevention mine gas dynamic disaster, and the designs of the slot parameter and layout are the key factors. We investigated the mechanical properties of slot samples and acoustic emission characteristics in different slotting numbers and angles by uniaxial loading tests. Texts indicated that, the coal strength was weakened by slotting and reduced significantly with increasing slotting numbers, and the coal was damaged easier when the slot plane was perpendicular to the axial stress. Meanwhile, exampled of Guhanshan coal mine 1603 working face, we analyzed the evolution of the coal fracture, stress and porosity when the slots were at the same level and at the different levels by numerical simulation of Particle Flow PFC2D. The results showed that, to the sample of slots at the same level, the area around the slot was damaged significantly, and the stress concentration was distributed between the adjacent slots, which was easily induced coal and gas dynamic risk. However, the stress and crack fields were distributed uniformly when the slots were at the different levels, the stress was decreased significantly and the porosity of coal was 1.5 times high than the original value.

Research on the negative pressure distribution law and its application for boreholes in coal seam bedding gas extraction

Linchao Dai — 2016-11-28

Borehole along the seam is a significant borehole distribution process of gas extraction in coal mine, which is a fundamental measure for preventing and controlling gas disasters, but also an important mean to explore coal-bed methane resources. Recently, the technology of borehole along the seam has been widely applied to gas extraction with the development of borehole rigs and kilometer-borehole rig appearing. Presently, the domestic scholars’ researches on the extraction theory mostly focus on pre extraction by borehole through beds and shallow borehole along the seam, few considering the influence of viscous mechanics of gas flow in boreholes. Therefore, the research on the variation of negative pressure inside the borehole along the seam in borehole direction is greatly important to guide the design of borehole along the seam to gas extraction, the determination of key parameters and the application of the technology in theory.

Focusing on research of distribution of negative pressure inside the borehole along the seam in borehole direction and its application, this paper studies two sections: (1)Research on distribution of negative pressure inside the borehole along the seam in borehole direction. Based on gas occurrence, flow theory, fluid dynamics theory and the definite mechanism of negative pressure inside the borehole along the seam on gas extraction, both gas flow models around boreholes and inside boreholes were established. Distribution of negative pressure inside the borehole along the seam in borehole direction was got by classifying the pressure loss inside boreholes and coupling the flow conservation equations of two models, so as to its influential factors. Distribution of negative pressure inside the borehole was technically determined by field tests, verifying the feasibility of the proposed models. (2)Application of distribution of negative pressure inside the borehole along the seam in borehole direction. Considering the shortages of traditional extraction processes, two new ones were put forward applying the distribution of negative pressure inside the borehole along the seam in borehole direction, the extraction pipe reaching a certain distance or covering the whole length. Technical processes such as theory analysis, field test and numerical simulation verified the superiority of the new extraction processes.

This study finally got the variation of negative pressure inside the borehole along the seam in borehole direction and the distribution of negative pressure inside the plume borehole along the seam, derived the calculating formula of reasonable borehole length, put forward new extraction processes and verified the superiority of the new extraction processes in some conditions.

Mathematical simulation and experiment of CBM detection

Qing-hua Liang — 2016-11-28

To accurately detect the underground Coal Bed Methane (CBM) accumulation in coal mining face by mine radio wave perspective method, this thesis simulated the characteristic curve of received values through coal seam, and discussed the feasibility of CBM. We conducted experiments in Chinese mine. The study concluded that the existence of CBM could cause abnormal area. Compared to the normal reception curve, the abnormal curve of CBM showed a much smaller value, and the attenuation was larger in middle area, smaller on both sides. The pattern formation was a "saddle" shape. Radio wave penetration method could be a more reliable detection for CBM in underground coal mine.

Numerical modelling and rescaled range analysis on spontaneous combustion under surface methane drainage in a Chinese coal mine

Xincheng Hu — 2016-11-28

In China, surface boreholes have been used frequently to drain methane/gas emitting from overlying layers and longwall mining gob areas in underground gassy coal mines. In this work, a numerical modeling was established using COMSOL^TM to study the influence of surface drainage borehole on coal spontaneous combustion and Rescaled Range Analysis (R/S analysis) was employed to investigate the chaos characteristic of Nitrogen (N₂)/Oxygen (O₂) drained from the gob. The simulation results show that there is a circular “dissipation zone” around the drainage borehole all the time and an elliptic “spontaneous combustion zone” when the borehole locates in deep gob. It is also found that the advancement of drainage borehole has little influence on spontaneous combustion zone on the intake side of the gob but it can tremendously enlarge the width of “spontaneous combustion zone” in the middle gob and reduce the depth of self-heating zone near the return side. The R/S analysis indicates that the influence of surface borehole on spontaneous combustion can be divided into two stages: the safety drainage stage (Hurst index > 0.85) and the spontaneous combustion initiating stage (Hurst index ≤ 0.85). It can be concluded that the gas drainage from gob through surface borehole can tremendously intervene spontaneous combustion "three zones" in gob. In addition, the length-fixed R/S analysis on N₂/ O₂ series from surface boreholes can effectively reflect coal spontaneous combustion condition in gob.

The strength properties of fibre glass dowels used for ground control in coal mines

Naj Aziz — 2016-11-28

Glass-Reinforced Polymer (GRP) bolts, commonly known as Fibre Glass (FG) dowels or plastic dowels are increasingly applied for strata reinforcement in mines as well as in concrete reinforcement in civil engineering. The most popular dowels used in Australian coal mines are the 22 mm diameter fully threaded type. FG bolts are cuttable, easy to handle, lightweight and corrosion resistant. The tested dowels were all black in colour, which is a favoured colour in coal mines. A series of tests were undertaken to evaluate various strength properties of FG dowels. These tests include the tensile failure test by the double-embedment method, single guillotine shear test, double shear test both in steel frame and in concrete blocks, and finally the punch shear test. The study found that the tensile strength by pull testing of the 22 mm diameter fibre glass dowels was in the order of 27 t. The shear strength testing of dowels in both single guillotine and double shear steel frames were in agreement with each other. In general the shear strength values of dowels tested, using single shear guillotine testing, were around 20% of the axial strength in comparison with 70% in the same diameter steel rebar tests. The peak shear load values obtained from double shear tests in concrete blocks was influenced by the encapsulation grout type and the level of fibre glass axial pre-tension. The punch shear tests revealed that there was a more than threefold increase in the punch shear strength value of fibre glass dowels tested perpendicular as against parallel to the dowel axis.

Numerical simulation for propagation characteristics of outburst shock wave and gas flow when outburst prevention facilities fail

Zhou Aitao — 2016-11-28

In order to numerical simulate the propagation law and counter current of outbursts gas flow when outburst prevention facilities fails, the propagation characteristics model of outburst shock wave and gas flow was established, and the mechanism of gas adverse current was analyzed. The propagation and counter of shock wave and gas flow at two types of geometry model were numerically simulated using Fluent software. The results show that the most of gas flow produced by outburst propagate to intake airway when crossheading with excavation roadway at the same level; however, when crossheading with the excavation roadway where outburst may occur is not at the same level, gas is mainly discharged from the return airway, and intake airway affected by the gas flow is small. The results have important theoretical and practical significance for mine disaster rescue and preventing secondary accidents.

Influence of fundamental internal parameters to low-temperature critical temperature in coal self-ignition process

Haiyan Wang — 2016-11-28

Low-temperature oxidation process of coal self-ignition can be divided into two stages-slow oxidation stage and fast oxidation stage. To study the effect of internal factors to low-temperature critical temperature in coal self-ignition process, 8 fundamental internal parameters (volatile, ash, fixed carbon ,C, N, S, H and O) and 3 characterization parameters of low-temperature critical temperature in coal self-ignition process (T_JR,T_CO and T_O2) were determined on theoretical analysis first, then the self-heating characteristics in pure oxygen atmosphere in the range from 40 to 180℃ and gas releasing atmosphere in the range from 30 to 180℃ for 7 coal samples were tested. Based on this, the values of fundamental internal parameters and characterization parameters for 7 coal samples were obtained. The relationship between fundamental internal parameters and that of characterization parameters were compared. On grey relational analysis, 5 important influence parameters are filtered to make mathematical formula fitting with characterization parameters. The result shows that characterization parameters reflect critical temperature from different aspects-temperature rising, CO releasing and oxygen consumption. They are different for the same coal sample, but are with the same tropism and confirm each other. Critical temperatures is negatively correlated with the contents of volatiles, H and O, not of determined relationship with the content of S and having small correlation with other parameters.

Experimental study of negative pressure gas drainage influences on coal moisture content

Shaojie Chen — 2016-11-28

In the light of water loss phenomena of coal by negative pressure gas extraction, the relationship between time and coal moisture content, rate of water loss in special condition of temperature and negative pressure were studied in laboratory, and the water lose mechanism of coal was analyzed. Results show that the moisture content of Three coals decreased as the negative pressure reaction time increases. In the initial phase, the moisture content of coals descends quickly, afterwards, the decrease trend slows, and finally the moisture content of coals tends to a constant value. The maximum saturated water loss rate reaches 82.19%, and the water loss of coals in experimental conditions is larger. The negative pressure by gas extraction reduces the coal pore gas pressure, and the boiling point and the saturated vapor pressure of water decrease; it increases the free water vaporization (no boiling) rate of coals. Adsorption water and liquid water can change from a liquid to a gas, and it was extracted by negative pressure, and this action would reduce the coal moisture content. The moisture of coal has great affected on dust quantity by mining. A long and continuous gas extraction will result in water loss of coal, and it is of great disservice to the coal mine dust prevention, so it is necessary to take water injection into coal seams or enhanced dust prevention measures after gas extraction.

The laws of gas-solid coupling of coal-bed gas in deep high gassy coal seams

Zhou Aitao — 2016-11-28

In order to analyze the laws of gas-solid coupling of coal-bed gas in deep high gassy coal seam as well as prevent the gas compound dynamic catastrophes of deep gas-filled coal-rock, simulation of the laws about gas-solid coupling of coal-bed gas which is under the influence of gas pressure, mining depth is made by establishing theoretical gas-solid coupling model and using COMSOL Multiphysics software. Research results indicate that under the influence of factors such as high ground stress and gas pressure, the mutual coupling interaction between coal and gas is much more significant, which leads to the emergence of new characteristics of gas compound dynamic disasters. Reducing the ground stress concentration in front of the working face can not only minimize the possibility of rock burst accidents which are mainly caused by ground stress, but also weaken the role of ground stress as a barrier to gas, thereby decrease the number of outburst accidents whose dominant factor is gas; The results have a great theoretical and practical significance on the further optimization of accident prevention technique as well as safety protection of mine, disaster prevention system design and accident emergency plan.

Grey Correlation Model of influence factors analysis of ventilation time in single-way tunnel

Yang Cao — 2016-11-28

Ventilation time is an important parameter in the process of heading face ventilation. Shortening ventilation time has great significance to improve the efficiency of tunneling work. Analyzing the influence factors affecting the heading face ventilation time and establishing the grey correlation model based on the ventilation time data of -118m single-way tunnel in a golden mine. Calculation of the correlation degree between the four influence factors are as below: blasting fume throwing length(X0), distance of air duct to tunneling face(X2), length of tunnel(X3), initial concentration of CO(X4), and going on evaluation on the sensitivity. Result shows that: Tunnel length and blasting fume throwing length are more sensitive to ventilation time in the four influence factors, distance of duct to the diving face is less sensitive to ventilation time, influence factors of initial of concentration is the least sensitive of all. Analysis result can create practical and instructive effect to ventilation work in single-way tunnel.

Numerical research on the airflow distribution in mine tunnels

Cui Ding — 2016-11-28

Based on the 3D model of typical tunnels in mines, the air flow structure in the three hearts arch-section tunnel was investigated and the influence of ventilation velocity and cross section size on air flow distribution in tunnels was studied and the average velocity points were analyzed quantitatively. The results showed that the air flow structure showed circular distribution which is similar with the shape of three hearts arch-section under different ventilation velocities and cross section sizes, . The shape of the cross section and the tunnel wall were the critical factors influencing the air flow structure. And the average velocity points were mainly closed to the tunnel wall. The characteristic equations were then developed to describe the average velocity distribution, which provide the theoretical basis for accurately measuring the average velocity in mine tunnels.

Application of a ventilation management program for improved air quality

Euler De Souza — 2016-11-28

The purpose of Ventilation Management Systems is to ensure the health and safety of underground workers by creating and incorporating structured Plans, Procedures and Processes on the day-to-day operations of the mine ventilation system. Application of Ventilation Management Programs consists of audit, verification and corrective action procedures used to, i) ensure adherence to regulatory standards or to ii) return to compliance and safety standards when an upset condition arises. The paper describes how a Ventilation Management Program can be developed and implemented to ensure regulation compliance, to increase safety, to improve operational efficiency and to reduce the operating costs of an operating mine. A case study is presented in which air quality conditions have been substantially improved with the development and implementation of a Ventilation Management Program for an operating underground hard rock mine.

Numerical study of simultaneous methane and coal dust dispersion in a room and pillar mining face

Yueze Lu — 2016-11-28

In underground coal mines, uncontrolled accumulation of methane and fine coal dust often lead to serious incident such as explosions. Therefore, methane and dust dispersion in underground is closely monitored and strictly regulated. Accordingly, significant efforts have been devoted to study methane and dust dispersion in underground mine. In this study, methane emission and dust concentration are numerically investigated using the computational fluid dynamics (CFD) approach. Various possible scenario of underground mine configurations are evaluated. The results indicates that solitary existence of continuous miner adversely affects the air flows and leads to increases in both methane and dust concentrations. Nevertheless, it is found that the negative effects of continuous miner presence on concentrations can be minimized or even neutralized by operating the scrubber fan on suction mode. In addition, it was found that the combination of scrubber fan on suction mode and brattice results in the best performance of methane and dust removal from the mining face.

Reducing heat stress exposure in mines

Ryan Anderson — 2016-11-28

Heat management must be maintained within the mine working environment to minimize stress on equipment and personnel. Proper application of engineering protocols and work practice controls will have a direct impact on the health and safety of workers and on productivity. Using monitoring stations placed in strategic locations throughout the mine to capture the environmental conditions, various strategies can be used in the planning and prevention of potential hazard exposure. Economic analysis is used to select the most feasible strategy for heat stress control.

Effect of hydrogen on explosion of methane-air mixture

Chunli Yang — 2016-11-28

Gas explosion is one of coal mine accidents in china. The main composition of the gas is methane, but hydrogen is contained in some coal seams and have some influence on gas explosion. In this paper, the main reaction path of gas explosion process is analyzed by CHEMKIN on the basis of detailed mechanism of methane combustion, and the main elementary reaction of effecting gas explosion at high temperature and the law of heat release from basic elements in gas explosion are analyzed. And effect of H₂ on gas explosion is analyzed by numerical simulation. The research results show that H₂ will reduce the priming induction period of gas explosion and has certain influence on the temperature and pressure after gas explosion.

Drilling escape and rescue system in Wangjialing coal mine

Zhiling Huang — 2016-11-28

As regard to the problems exposed in the construction of emergency refuge system, including the poor reliability of hedging facilities, the contradiction between hedge and escape, time consuming, high cost and big risk of drilling rescue technology, etc., shaft drilling escape and rescue system is brought up, which is a combination of emergency refuge technology and drilling rescue technology. Through doing researches on man-loading experiment and live sheep lifting experiment, key parameters of drilling escape and rescue system are tested, like no-supply guarantee time, response time, human survival environment and so on. This paper also studies comfort and physiological parameters of experimenters and the influence drilling has over refuge chamber air supply system.

Effects of immediate roof thickness on lower sub key strata movement in ends of large mining height panel

Chuang Liu — 2016-11-28

Based on the 58 geological drill holes around panel 42105 in the Ordos coal field, a 3D geological model and 2D numerical model with real strata conditions were established. With the models, the effect of the immediate roof thickness on the ground pressure can be studied, and the roof movement patterns under the different immediate roof thickness can be explored. Mechanical models of the lower sub key strata under different immediate roof thickness were achieved by using the field measurement, theoretical analyses and numerical simulation method. Meanwhile the effect of immediate roof thickness on lower sub key strata movement in ends of large mining height coal face was studied. The discrimination formula of the movement patterns was deduced. Theresearch findings show that: when the immediate roof is relatively thick, the fractured lower sub key strata can be hinged to form a stable “Voussoir Beam” structure, which makes the ground pressure not severe and the shield pressure small in the ends of the panel; when the immediate roof is thin, the arc triangular of the lower sub key strata in the ends of the panel loses mechanical contact to the caved immediate roof and assumes a “Cantilever Beam” structure, which makes the ground pressure severe and shield pressure large in the ends of the panel.

Study on the performances of a protective door in coal permanent refuge havens

Na Gao — 2016-11-28

An effective protective door for a underground refuge haven has anti-explosion, anti-pressure, and sealing capabilities. In this study, Wulan Coal Mine’s actual situation and the technical requirements for the protective door in the permanent coal refuge haven were analyzed, a numerical simulation analysis for the anti-explosion performace was performed, and the materials, structure, and the sizes of the protective door were confirmed. Further, two experiments on the protection and waterproof abilities of the door were conducted. The results showed that a 15-mm thick 16 manganese steel plate door can meet anti-blast and economical requirements. In addition, a manual wedge-shaped lock structure, a single-cast door wall, and a welding steel supporting structure can satisfy the airtight sealing and anti-pressure requirements. In the numerical simulation of the blast effect, it was observed that the maxnium displacement was at the center of the door, and the region of the highest stresses was around the door. The protective door could bear a 1 MPa explosion impact, and it could withstand a 1.86 MPa static pressure load with a deformation of 5.8 mm. Further, the door maintained good sealing perforemance until the hydraulic pressure exceeded 1.6MPa with a deformation of 14 mm.

Numerical modelling of the goaf: Methodology and application

Samar Ahmed — 2016-11-28

The mechanical behavior of the goaf is a critical issue that may affect the efficiency of long-wall mining. Goaf numerical modelling as a continuous material is a challenge, especially because its large-scale mechanical properties are not precisely known. Many different values of the elastic modulus may be found in literature to be used for representing the mechanical behavior of the goaf area. In this research, the elastic numerical modelling is shown to be a useful tool for simulating the stress redistribution and displacement due to long-wall mining with taking into account the goaf geometry and its equivalent mechanical properties. The analysis is applied on the Provence coalmine, in the south of France, which had been in operation for more than 50 years where the long-wall mining method was used. A finite difference numerical model of the mine is constructed and two approaches are carried out in order to simulate the goaf area above the excavated panels where the panels have various length to width ratios. In the first approach, the caved zone and the fractured zone have different but homogeneous elastic modulus, both zones have elastic modulus lower than the unaffected host rock. In the second one, their elastic modulus varies linearly with the vertical distance above the panel, up to the elastic modulus of the host rock. In both cases with and without goaf, the subsidence at the ground surface is calculated and compared with in-situ measured values. Results show that attributing to the goaf area a low elastic modulus increases the vertical stress within the rib pillars as well as the subsidence at the surface. The elastic modulus for the direct roof above the panel after excavation has found to be 225 <= E_{immediate-roof}(MPa) <= 180 in order to satisfy the total convergence between the roof and the floor. Representing the goaf area as a material with linearly varying elastic modulus gives rational results in terms of convergence and ground surface subsidence.

A coal enterprise scientific-technical progress evaluation system based on the Internet

Shanyang Wei — 2016-11-28

The evaluation of coal enterprises of scientific-technical progress is a big problem of technology management. Until now, In China or abroad there is no mature and recognized coal scientific-technical progress evaluation system that can make a wide range of evaluation about the coal scientific-technical progress of the whole country or region. in the quantitative measure aspects of scientific and technological progress to economic growth，although there were quite a few successful application researches. Especially, under the present condition of a lot of coal enterprise output decline, laid-off personnel and the assets reorganization, using the traditional production function to measure method is difficult to measuring the effect of technological advances to economic growth problem. On the basis of investigation and study, according to the actual situation and balance of payments structure of coal enterprises and with reference to relevant policies and regulations of the national science and technology evaluation, and with the application of universality and agility of the Internet, we constructed a system of the scientific-technical progress evaluation of coal enterprises. According to the computing applications of part of the state-owned key coal mines and local state-owned coal mines, good results have been achieved.

Simulation of strata behaviour laws of a coal mine in Jungar Coalfield

Bin Zhu — 2016-11-28

For the overburden movement, the roof collapsed, severe wall caving and a range of other issues of mine ground pressure caused by exploitation process in Jungar coalfield, the author systematically studied the performance of the law of overlying strata caving, mine ground pressure and crack development when the first coal mining face was exploited by means of similar material experiment. The results prove that the pace of the immediate roof caving of the first coalface is about 15.0 m; the pace of the first weighting of the rock stratum of main roof is 45 m, an average pace of periodic weighting is 17 m. The maximum loading-increasing factor of first weighting is 1.40, and the value of loading-increasing factor of the whole weighting period is 1.32; while the distribution of the three zones of the overlying strata on the first coalface, the height of the caving zone is about 4.5 times of the average mining height, the height of fissure zone is about 14.5 times of the mining height; and bending zone is the stratum over 43 m from the coal roof, which takes on the feature of overall moving down. Therefore, a reasonable choice of mining method to reduce the thickness of the mining working face and other measures should be taken to reduce the disturbance from exploitation to overlying strata of upper goaf and the earth's surface.

Goaf area exploration in Anjialing surface mine based on the C-ALS

Jun Wang — 2016-11-28

Using C-ALS(Cavity-Auto scanning Laser System) to explore goaf and to establish a three-dimensional model in mining boundary of Anjialing surface mine could ensure the production safety. Three-dimensional laser scanner elevation is consistent that verified by drilling exploration goaf roof elevation. Coal seam is shallow in Anjialing district, small coal mining had a long history and the central of first mining area distributed small kiln mining area, these damaged severely the 4^th and 9^th coal seam. Goaf three-dimensional laser scanning technology as an advanced goaf measuring instruments had be widely used at home and abroad mine, using C-ALS for 1302 and 1316 level in Anjialing district carrying out goaf exploration, obtaining volume of goaf are 21138m³, and carrying out data processing and three-dimensional modeling for goaf, for subsequent safety evaluation of goaf, disaster warning and governance programs of goaf provide basic basis.

Application of the strength reduction method in coal mine roof support design

Gabriel Esterhuizen — 2016-11-28

Ground falls represent a significant proportion of injuries and fatalities in underground coal mines in the US. During 2013, ground falls were responsible for 4 of the 14 fatalities and 16.6% of the 1,577 reportable lost-time injuries. In addition, each year about 400 to 500 large roof falls are reported that can extend up to or above the bolted horizon. Support design for coal mine entries is largely based on past experience and a trial-and-error approach. A numerical model-based approach for support design is presented in which calibrated models are used to determine a stability factor for a supported entry. The stability factor is determined using the strength reduction method (SRM). Applying this technique, the relative merits of various support systems can be evaluated. The numerical models allow the contribution of individual support units to overall stability to be assessed. Two case histories are presented. In the first case the SRM approach is applied to assess the use of passive cable anchors as primary support in a room-and-pillar coal mine. The second demonstrates how the SRM approach was used to evaluate the impact of angled bolts at the rib-roof corner on roof stability. It is concluded that the SRM approach provides useful information to assess the overall degree of stability achieved by a support system, and allows support elements to be optimized for particular geological and stress conditions.

Numerical simulation of the migration laws of supports and surrounding rock for coal seams of large dip angle

Zhi-an Huang — 2016-11-28

SDIC Nileke mine district contains 6 minable seam layers, which is located in Xinjiang. The average 45º dip angle of mine results in complex process of the mining working face. Processes such as support moving and mining working face advance are restricted and affected. The lateral stress of the roof increases, at the same time the problem of controlling the working face roof are serious. Based on field actual conditions, FLAC^3Dwas used to simulate the process of excavation and supporting of the mining working face. This study can provide technical support for safety production through the reasonable support mode which was obtained by the simulation of mine pressure behavior of working face.

Theoretical analysis of support stability in large dip angle coal seam mined with fully-mechanized top coal caving

Ying-hua Zhang — 2016-11-28

Support stability is all along one of the problems in mining at large dip angle coal seam with fully-mechanized top coal caving. Support stability such as anti-dumping, anti-slip, and anti-rotation at support tail assembly were analyzed on the basic of the mechanic model of large dip angle coal seam along face dip and strike. The relations between each factor and stability were researched, which shows, firstly, the support stability was negatively correlation with dip angle along the face dip, secondly, higher top caving means lower anti-rotation at support tail assembly, thirdly, with initial support force and working resistance of support enhanced, the support anti-slip, and anti-rotation at tail assembly can be risen significantly. Along the strike, support strike critical tilting angle is proportional to dip angle, mining height, support weight, support width and support force. Similarly, support strike critical slip angle is positive correlation with support force, friction coefficient of roof and metal support. According to the results of mechanic analysis, support stability in large dip angle can be risen efficiently and support slipping, dumping and rotation can be avoided by selecting proper technology method such as enhancing initial support force appropriately and choosing fit-designed support.

Theoretical research on roof damage of the fully mechanized top-caving mining coal seam with deep dip angle

Ying-hua Zhang — 2016-11-28

In order to study on roof pressure of the steep coal seam, it is very necessary to establish a related mechanical model to analyze the roof breaking law. Based on a working face of SDIC Nileke Mine, a mechanical model of roof facture of deep dip angle coal seam when first roof weighting and periodic roof weighting was built in the study. The model was analyzed in dip direction and along the advancing direction of the working face. Based on the stress analysis of the model, the formula about the distance of roof breakage was given. The stress, deformation and failure discipline of complicated full mechanized top-caving coal seam with deep dip angle were studied, which enriched the theory of roof damage as also. The research conclusions provide theoretical basis for the coal mine safety support, and other similar research on the roof failure discipline of full mechanized top-caving coal seam with steep dip angle can use it for reference.

Characteristics of acoustic wave velocity variation in the process of deformation and failure of loading coal

Xiangchun Li — 2016-11-28

For studying characteristics of acoustic wave velocity change during the deformation and fracture of loaded coal, using self-made acoustic parameter test system the characteristics of acoustic wave velocity change in deformation and fracture of loaded coal, the mechanism of stress influencing acoustic wave velocity change, the relation between stress and longitudinal wave velocity and the impossibility of longitudinal wave velocity forecasting coal structure is studied. The research results show that during the deformation and fracture of loaded coal the longitudinal wave and shear wave velocity increases firstly. When the coal is damaged the longitudinal wave velocity decreases and the shear wave disappears. The stress-strain change of coal is similar to the stress-wave velocity change highly. Based on coal structure the formula of stress and longitudinal wave velocity is established and the longitudinal wave velocity can be predicted well under different stress by the formula of stress and longitudinal wave velocity. The mechanism of stress influencing acoustic wave velocity change is coal structure change mainly.

Numerical simulation technique for gateroad stability analysis under fractured ground condition

Lishuai Jiang — 2016-11-28

The ground stability of gateroads is a major concern in underground coal mines, especially where the surrounding strata are weak and fractured. This paper presents a novel numerical modelling technique for gateroad stability analysis based on a case study conducted in Zhaogu No.2 mine, China. Considering the occurrence of fractures and its weakening effect on the stiffness of rock mass, a tension-weakening model is implemented into FLAC3D, whereby the stiffness of rock mass is progressively decreased according to failure state. A relationship between the intensity of fractures and the residual properties is built. A parametric study of the tension-weakening model with respect to weakening parameter is carried out, and the results are compared to perfect elasto-plastic model and strain-softening model. The comparison shows that the tension-weakening model exhibits a noticeable effect on ground deformation and rock support loading, and can simulate more realistic behavior of a gateroad, which agrees well with field measurements. The proposed model provides a rigorous approach for gateroad stability analysis and can be utilized for rock reinforcement design under similar geotechnical circumstances.

Organizing Committee

Editorial Staff — 2016-11-28

Organizing Committee

b-value as a criterion for the evaluation of rockburst hazard in coal mines

Grzegorz Mutke — 2016-11-28

Every year a few rockbursts with fatalities and a few hundred meters of damaged excavations have occurred in the mines of Upper Silesia Coal Basin (USCB) in Poland. The paper presents one of methods for assessing the level of seismic and rockburst hazard, using continuous seismological observation in Bobrek coal mine. This assessment is based on the study of the Gutenberg-Richter (G-R) relation for the current and past mining in the coal field. According to many laboratory and field studies, the b-value may be an indicator of the fluctuations of stress levels, e.g. Scholz, 1968; Gibowicz, 1974, 1979, and the consequent seismic hazard.

The novelty of the presented research is the development of quantitative criterion based on the b-value changes, calculated in a moving time windows with the 1 day step and the anomalies resulting from the comparison of the temporal values of b with its average value for the past seismicity in the field of coal mining; A_G-R =[(b_m – b)/b_m]·100% (where: b_m – average value of b for field of coal mining, b – temporal value of coefficient b calculated in time windows). This approach allows us to standardize the criterion to the current values of b in the investigated area (Table 1). In many measurement examples, high values of the temporal anomaly A_G-R and at the same time downward trend and low b-value before the occurrence of the strong mining seismic events, were documented in this paper and in studies by Pierzyna, 2014). Particularly interesting results were obtained for mining and geological conditions that led to the formation of the local zones of stress concentration, e.g. Dubiński, 1989, and an increase in seismic activity and seismic hazard.

The b-value criterion be in agreement with the four basic levels of rockburst hazard used in Polish coal mines, e.g. Mutke et al., 2015.

Quantitative evaluation of stope damage induced by seismic waves

Atsushi Sainoki — 2016-11-28

In the present study, a methodology to evaluate damage around underground opening due to seismic waves arising from mining-induced fault-slip is proposed. First, expressions for an associated flow rule with a failure criterion developed for biaxial stress conditions are derived, which are newly implemented into FLAC3D code. With the code, stope extraction is simulated, using a 3D mine-wide model encompassing a fault running parallel to a steeply dipping orebody. The failure criterion for biaxial stress conditions is applied to only the rockmass in the vicinity of stopes within the hanging wall. After extracting stopes in the orebody, mining-induced fault-slip is simulated in dynamic conditions, considering its trigger mechanism, i.e., stress drop caused by instantaneous shearing of fault surface asperities, using Barton’s shear strength model. Damage to the rockmass caused by seismic waves is then evaluated with the increase in plastic strain. The proposed methodology takes into account the mechanism of mining-induced fault-slip, propagation of seismic waves, biaxial stress conditions on the surface of openings, and plastic strain as damage criterion.

Influence of weak planes on rockburst occurrence

Amin Manouchehrian — 2016-11-28

Geological structures such as faults, joints, and dykes have been observed near excavation boundaries in many rockburst case histories. In this paper, the role of weak planes around tunnels in rockburst occurrence was studied. An Abaqus explicit code was used to simulate dynamic rock failure in deep tunnels. Firstly, Abaqus’s usefulness for modeling geomaterials was improved by introducing material heterogeneity using Python scripting. Modeling results showed that heterogeneous models resulted in more realistic failure modes than homogeneous models. Secondly, rock failure near the excavation boundary of a tunnel without any adjacent geological structure was modeled and released kinetic energy from rock due to failure and velocity of elements at the tunnel wall were calculated. Then, a weak plane was added to the model. This resulted in more released kinetic energy and higher element velocity, indicating that rock failure became more violent in the models with weak planes. The modeling results confirm that the presence of geological structures in the vicinity of deep excavations is a condition for the occurrence of rockburst. It explains localized rockburst occurrence in civil tunnels and mining drifts. The presented methodology in this paper for rockburst analysis can be useful for rockburst anticipation and control during mining and tunneling in highly stressed grounds.

A model of rockburst including geological dynamic conditions and mining

Jun Han — 2016-11-28

Rockburst is one of the most serious disasters which threaten the safety of mining and occur under certain combinations of geologic and mining conditions. A model of fault-slip burst based on energy of rock mass was developed to illuminate the mechanics of rockburst and assess the treatment parameter in underground coal mines. In this model the energy of a fault involved in rockburst is be assumed to be spheroid. The energy of rockburst is from the rock mass of spheroid and rock mass ahead of development. The critical energy condition of rockburst is used for estimate of rockburst occurrence. As an application the advance distance of rockburst treatment ahead of geological structure can be obtained.

Rockburst experiences in Cheves Hydropower Project, Perú

Santiago Veyrat — 2016-11-28

Cheves Hydropower Project is located in Peru and consists in approximately 20 km of tunnels and two caverns. Most of the Headrace tunnel has been excavated in igneous and metamorphic rocks with high overburden. A high number of stress release events took place during the excavation of the tunnels and caverns. The intensity of these events varies from acoustic emission to a violent rockburst. The paper describes the methodology developed to mitigate the rockburst hazard.

Rockburst mitigation experiences on underground projects in the Cheves Hydropower project in the Peruvian Andes

Santiago Veyrat — 2016-11-28

The main problems related with the design and construction of tunnels and caverns under high overburden are analyzed in this paper. As an example, the recent experiences during the construction of Cheves Hydropower Project in the Peruvian Central Andes are described. During its construction, 850 rockburst events were recorded, enabling designers to collect data and make some correlations that may be useful for other projects.

Destress blasting on the border of safety pillars

Petr Konicek — 2016-11-28

Destress blasting used at the border of safety pillars represents a special kind of destress blasting. The main goal of this type of destress blasting is to separate relatively more deformed mining areas from a non-mined safety pillar area such as shaft pillar or cross-cut pillar and this way to reduce the impact of high stress concentration in areas within the safety pillar.

Destress blasting is carried out in rigid, competent rocks adjacent to hardcoal seams 5 m to 6 m thick at depths ranging from 700 m to 1000 m below surface. Total explosive charge of up to 3450 kg is fired simultaneously in three to seven fan-pattern and line-pattern boreholes drilled from the maingate and the tailgate when the longwall face approaches to within round 100 m of the safety pillar border.

Experiences of this type of destress blasting from hardcoal longwall mining in the Czech part of the Upper Silesian Coal Basin are described here. Natural and mining conditions are described together with the design parameters of destress blasting, registered seismic activity during longwall mining and evaluation of the stress relief effect calculated from the monitored seismological data. Authors present arguments for using this kind of destress blasting as a proactive rockburst prevention measure during mining of thick hardcoal seams. Destress blasting can decrease high stress levels and consequently minimize rockburst hazards on the border regions of the safety pillars.

Keywords: Destress blasting, rockburst protection, stress distribution

Powered support selection for longwall workings in dynamic load conditions

Stanislaw Prusek — 2016-11-28

Currently in Poland hard coal is mined in two Coal Basins namely Upper Silesian and Lublin. The Upper Silesian Coal Basin is located around the city of Katowice in the southern part of Poland. The Lublin Coal Basin is located in the south-eastern part of Poland, close to the Ukrainian border. In Poland, there were 30 underground hard coal mines that produced 72.5 million tons of coal in 2014. For underground hard coal seam extraction, the longwall method is used. Retreat longwalls with natural roof caving in the gob are the most common. Currently it is estimated that about a half of the hard coal output in Poland originates from seams located in areas of rock burst hazard. In the paper, the most important data concerning the geological and mining conditions in Polish hard coal collieries were presented with particular emphasis on tremors, rock bursts and fatalities. Moreover, the article shows information about 18 rock bursts, and 14 other seismic events which occurred between 2003 and 2012 in underground mines belonging to one of coal companies in Poland. In addition, negative consequences of those dynamic phenomena in the longwall workings are described. In the next part of paper, the most common types of damage to powered supports after the rock mass tremors and other dynamic phenomena in longwall workings are shown. In order to avoid damage of powered supports, in geo-mining conditions where dynamic phenomena occur, different types of protective means are applied. In the paper the methodology of assessing the powered support yield ability is described. At the end, an example of the assessed yield ability of a powered support in given geo-mining conditions of a longwall face affected by the seismic events is presented.

Evolution of grouting methods for dynamic supports in broken ground

Francois Charette — 2016-11-28

Rockbursts are seismic events of deep or high stress mines that often lead to damages to the ground support system. Even when the rock at the contour of the excavation is broken, rockbursts can occur behind this soften zone and damage the support system further. In these broken conditions, the ductility of the ground support system is still critical, but the installation of grouted tendons is rendered tedious or very inefficient by the problems associated with inserting cartridges of resin inside the boreholes. The same practical issues with resin cartridges arise while bolting in squeezing ground conditions or in damaged pillars.

This study aims at investigating alternative methods of grouting dynamic rockbolts by methods other than the polyester resin cartridges traditionally used by the mining industry. In particular, the use of injected resin grout for reinforcement is analysed in the field. The static anchorage capacities of the injected resin is evaluated using D-Bolts and Self-Drilling Bolts (SDB) by the mean of pull out tests, and compared with the performance of similar bolts anchored with resin cartridges in hard rock conditions, and grouted with cementitious grout. Drop tests evaluation of the resin was postponed due to scheduling difficulties.

The study also includes a field evaluation of the installation method, sequence and bolting speed, for typical length tendons. The implications of the installation with injected grout on the resulting capacity and estimated safety performance are discussed.

Large scale panel destress blasting parametric study

Isaac Vennes — 2016-11-28

The purpose of this parametric study is to quantify the effect of panel destressing on a steeply dipping remnant ore pillar. A large-scale destress blast program is simulated in the hanging wall of the ore pillar using the finite difference program FLAC3D. The simplified model consists of a 10MT ore pillar divided into 20 stopes on two levels. Two panels are destressed in the hanging wall to cover 8 stopes, followed by the mining of 4 stopes in the stress shadow in a retreat sequence. The varied parameters are the rock fragmentation factor (α) and stress reduction factor (β) of the destress panel. The effect of panel destressing is evaluated based on the volume of ore at risk in the stress shadow as well as the sudden stress change in the stope caused by the destress blast. Overall, a successful blast with a realistic stress reduction factor and rock fragmentation factor reduces the major principal stress in the nearest stopes by 10MPa to 25MPa. This yields a reduction of ore at risk volume ranging from 8% to 50% in the stress shadow as the first 4 stopes are mined.

Improving ground control safety in deep vein mines

Joseph Seymour — 2016-11-28

Researchers with the National Institute for Occupational Safety and Health (NIOSH) in Spokane, WA, USA are conducting research in collaboration with the Hecla Mining Company at the Lucky Friday Mine in northern Idaho to improve ground control safety in deep vein mines. Because Hecla is mining at depths of more than a mile beneath the surface, the geology and ground stresses create unique requirements for mining and ground support. Special measures are being implemented by Hecla to limit the intensity of mining-induced seismic events and to avoid compromising the static and dynamic capacity of their ground support systems. NIOSH researchers are studying these efforts by monitoring and assessing the fault slip mechanisms that initiate these seismic events and by quantifying the performance characteristics of the ground support systems.

Numerical investigation of EDZ development around a deep polymetallic ore mine

Mountaka Souley — 2016-11-28

This paper deals with the development of a non-linear constitutive model of rock mass and its verification to predict a damaged zone. Simulations of triaxial compressions provide a verification of the implementation with a good agreement between predictions and theoretical values of peak and residual strengths as well as the transition between brittle failure and ductile response. The applicability of the model to predict potential failure around stopes of a deep polymetallic ore mine is checked and highlighted the interest to consider more realistic rheology of hard rock masses compared with the elastic perfectly plastic models of underground deep mines.

Estimating the probability of unsatisfactory performance associated with the instability of mine developments

Wael Abdellah — 2016-11-28

Mine developments are the main access to extract tabular ore deposits in deep underground mines. Therefore, their stability is considered the principal priority during the mine production plan. The success of ore extraction mainly depends on the stability and servicibility of mine developments. Mine development instability is expensive and is a risk to personnel and equipment and in turn, it will raise the operational cost (e.g, repair costs: slashing, rehabilitation costs, costs of adding secondary support, miners wages and delay of production) (Ellefmo, and Eidsvik, 2009; Abdellah et al. 2014a, 2014b and 2014c). This paper aims to develop a hybrid approach in which deterministic numerical modelling is integrated with probabilistic methods to estimate the probability of unsatisfactory performance (e.g. rating and ranking) associated with the instability of mine developments with respect to mining sequences adopting Rosenblueth’s Point-Estimate Method (RPEM). A three-dimensional, elastoplastic, finite difference model (FLAC3D) is created (Itasca, 2009). The results are presented and categorized with respect to probability of instability and mining stage.

Numerical modelling of time-dependent skin degradation of an isolated pillar

Atsushi Sainoki — 2016-11-28

The present study focuses on the mechanism of instability of an isolated pillar caused by time-dependent skin degradation and strength heterogeneity. The time-dependent skin degradation is simulated with a non-linear rheological model capable of simulating tertiary creep. The inherent strength heterogeneity is realized with the Weibull’s distribution. Results obtained from the analysis shows that the skin degradation is limited to regions near the surface until two months after extracting ore, but afterwards it starts to extend deeper into the inside, eventually leaving a highly stressed pillar core due to the stress transfer from the failed rock. Rockburst potential indices show that the risk increases exponentially at the core as time goes by. It is then demonstrated that the progressive skin degradation cannot be simulated with the conventional strain-softening model assuming brittle failure. The parametric study with respect to the degree of heterogeneity reveals that the heterogeneity is a key to the occurrence of progressive skin degradation. Although average UCS in the model with high degree of heterogeneity is almost the same as that in the model with low degree of heterogeneity, the degradation of rockmass extends deep into the pillar only in the highly heterogeneous model.

Quantitative analysis of haulage system instability in deep hard rock mines using numerical modelling

Shahé Shnorhokian — 2016-11-28

Haulage drifts and related infrastructure are crucial to the success of underground mining operations. In the sublevel stoping mining method, they are developed well before any extraction commences in a given section of the orebody. One of the more complex design parameters is the relative distance of a haulage drift from the orebody as it runs parallel to its strike. Opposing considerations from operational and ground control teams are balanced, with the former preferring a shorter distance for increased productivity and the latter requesting a further distance for safety and stability. Numerical codes are one of the analytical tools used frequently in making these decisions by providing mining-induced stress and displacement magnitudes with a properly calibrated model. In this study, a simplified model is constructed of a typical tabular orebody within the geological settings of the Canadian Shield, striking East-West and dipping steeply to the south. Three other formations with the same strike and dip are added to the model, along with two intrusive dykes at variable distances from the orebody and the drift. The rockmass properties for all formations are taken from a previous work on a case study mine in the Canadian Shield, and the model is calibrated based on in-situ stress measurements there. Two stope sequences comprising two simultaneous mining fronts are implemented and analyzed for the orebody; a diminishing pillar one that moves from both east and west to the middle, and a centre-out option that moves from its centre to the sides. In both cases, 24 mine-and-backfill stages – comprising 6 stopes each – are needed to completely extract the orebody. A quantitative assessment of instability around the drifts, crosscuts, and stopes is conducted for a single level at a depth of 1490 m for each stage. Three instability parameters – the brittle shear ratio (BSR), uniaxial compression, and tensile failure – are combined with volumetric analysis to obtain the quantity of potentially unstable rockmass. The relative proximity of the drift and stopes to the dykes is evaluated as well and observed to have an impact on the results. A combined numerical-volumetric approach is found to provide a useful tool for comparing different sequences and obtaining information on the type, location, volume, and timing of rockmass instability.

Minimum strength required for resisting cyclic softening/failure of cemented paste backfill at early age

Tikou Belem — 2016-11-28

This paper attempts to assess empirically the liquefaction susceptibility of cemented paste backfill (CPB) at early age (£ 7 days). Early age CPB can be categorized as a “clay-like” material because their plasticity index, PI ³ 5 (PI = Liquid Limit, LL – Plastic Limit, PL). For clay-like material such as CPB, the liquefaction susceptibility can be characterized by the “cyclic softening” or “cyclic failure” which is assessed using an empirical method developed for clays and clay-like materials. This analysis allowed determining the minimum undrained shear strength required to resist cyclic softening (failure) of cemented paste backfills which is directly related to the unconfined compressive strength (UCS).

Analysis of failure in a salt room and pillar mine

Farid Laouafa — 2016-11-28

Failure mechanisms have been investigated in a salt mine (Alsace Potash mines, Esat of France) excavated by the room and pillar method. A part of this is under study for chemical waste storage. This part is located at about 550 meters depth. Some quite singular failure modes appear in the roof mine. They are perpendicular to the axis of the gallery and are created without any doubt by tensile stresses. Such a failure mode is rarely observed in classical mines (coal, construction stones, etc.). 3D modeling of the site has been required for accurate description of the physical mechanisms. The results show that the failures and more generally the roof behavior are controlled by the deformation of the pillars inducing tensile forces in the roof. We also show that the creep or the viscoplastic behavior of the salt is a key element that explains the existence of such failure and their evolution over time. A parametric analysis of the properties of overburden, geometrical pillar features slenderness, confirm the conclusion. Namely, time-dependent deformation of large salt pillars generates their lateral extension and induces roof deformation and failure in tension. The numerical results are in full agreement with in-situ observations.

Lessons in slope stability management from Kinross’ Tasiast mine, Mauritania

Korhan Tasoren — 2016-11-28

The continued monitoring and optimization of a mining operation are essential extensions of a feasibility study. While the ultimate goal is to mine to the planned design in a safe and economic fashion, such efforts are challenged on a daily basis by changing ground conditions. Success in a dynamic mining environment requires a strong understanding of historical instabilities and wall control blasting, along with well-defined near wall excavation and clean-up procedures, and an advanced slope monitoring system. This paper presents several cases describing different modes of slope failure experienced at Kinross’ Tasiast mine site, and the operational and design measures implemented to manage and monitor these instabilities. Routine data collection practices and blasting designs that have been introduced to minimize wall damage and steepen slope angles are also discussed.

Effect of buttress on reduction of rock slope sliding along geological boundary

Ryota Moriya — 2016-11-28

In open−cut limestone mines in Japan, huge rock slopes with geological boundary between limestone and bedrock have been formed by mining activities. In addition, latent sliding plane near the toe of slope may be formed through the development of damaged zone with increase in size of rock slope. It has been reported that inelastic time−dependent sliding deformation of rock slope along both the geological boundary and latent sliding plane can occur. In this case, one of the countermeasures to suppress sliding deformation is an application of rock buttress to the slope surface where the sliding is taking place. However, effect of rock buttress on reduction of the rock slope sliding has not been clarified yet. In this paper, the effect of rock buttress on reduction of the rock slope sliding was discussed based on 2−dimensional finite element analysis using non−linear visco−elastic model. The results indicate that (i)degree of deterioration of sliding plane at the timing of the application of rock buttress significantly affects the expected life of rock slope, (ii)optimum height of rock buttress can exist, (iii)larger Young's modulus of rock buttress results in the longer expected life of rock slope and (iv)the balance of increase and decrease of normal and shear stresses on sliding plane by buttress is important and the obtained results can be changed by the difference of friction angle and the geometry of sliding plane.

Validation of empirical rock mass classification systems for rock slopes

Hassan Basahel — 2016-11-28

ABSTRACT

Many classification systems have been proposed in the literature to identify the state of stability of rock slopes. Most of these classification systems involve factors relevant to the general condition of the rock mass, for example, intact rock strength (UCS), geometry and condition of discontinuities, and groundwater condition. Such factors represent the basic part of most of the classification systems, which refer to the well-known Bieniawski’s Rock Mass Rating or RMR system. However, these factors were initially developed for underground excavations. Therefore, these classification systems have been subjected to many criticisms and were questioned for their suitability for rock slopes.

In this paper, some of the common classification systems for rock slopes are used to identify their suitability for rock cuts. Twenty two sites of rock cuts in mountainous roads affected by heavy rainfall in the southwestern part of Saudi Arabia have been selected as case studies, and four empirical methods are examined for these case studies. Theselected methods are Slope Mass Rating or SMR (Romana, 1985), continuous SMR (Tomás, 2007), Chinese SMR (Chen, 1995), and a graphical SMR (Romana, 2012). The stability conditions for each site have been determined by each of these methods and a comparison between the results is made for the case of plane failure mode. It is shown that some of the empirical methods are not applicable such as Chinese SMR (for slopes less than 80 m high), and the graphical SMR method when the slope angle is more than 80°.

Application of InSAR for monitoring deformations at the Kiirunavaara Mine

Karola Mäkitaavola — 2016-11-28

An integral part of sublevel cave underground mining is the associated caving of the surrounding host rock. This causes mining-induced ground surface deformations on both the hangingwall and footwall side of the orebody. The municipality of Kiruna, in northern Sweden, is located in close proximity to the LKAB Kiirunavaara mine and is thus unavoidably affected by the mining activities. To be able to plan for an urban transformation, as the effects of mining approach the city infrastructure, it is necessary monitor the ground deformations on a regular basis. Historically, GPS-monitoring has been used, with an extensive network of measurement hubs in place. New techniques for monitoring ground deformations are, however, constantly evaluated. As part of this process, LKAB has conducted a five-year research and development project on deformation measurements using radar satellites and the InSAR technology. The project has included a monitoring component and a research- and technology transfer component. The overall findings of the monitoring program, and the associated research and development work are presented. Particular emphasis is put on achieved accuracy and the implications for the ability to reliably monitor the progressing deformations toward the municipality and existing infrastructure. Lessons learnt from the conducted work are presented, followed by recommendations on future use of InSAR for this type of application.

Modelling the impact of particle flow on rigid structures: Experimental and numerical investigations

M.A. Meguid — 2016-11-28

Gravity-driven debris flow of granular particles down an inclined slope is a problem of growing concern in mountainous regions and poses a significant risk to people, roads, and other infrastructure. Different aspects of the problem have been previously investigated using physical modeling and numerical analysis. However, three dimensional pressure distribution on a barrier wall resulting from debris flow over a rough slope is scarce in the literature. In this study, a series of experiments have been conducted to track the movement of granular particles down a slope and measure the impact pressure imposed by the flowing particles on a nearby vertical wall. The particles are released from a container located at the top of the slope and the velocity profiles are recorded using marked pebbles and a high speed camera. The roles of the debris volume, slope angle and distance to the wall on the velocity profiles and impact forces are investigated. Validated using the experimental results, discrete element simulations are performed using PFC^3D to evaluate the effect of particle sizes on the flow characteristics and final impact pressure on the structure. Analysis showed that impact energy is highly affected by the slope inclination, particle velocity and runout distance.

A versatile model for the evaluation of subsidence hazards above underground extractions

Peter Cain — 2016-11-28

All underground extraction – oil, gas, water and minerals – results in subsidence of the surface to some degree. Subsidence can cause damage to infrastructure – roads, powerlines, gas and oil pipelines, buildings – and to the natural surface, with the development of cracking, potholes, changes in hydrogeology and destabilization of slopes. Pre-extraction estimates of the amount of subsidence and the hazards it might produce are difficult to determine with accuracy, and the most frequent approach is to model the surface movements in response to extraction using empirically based models.

There are a number of large underground coal mine projects on the drawing board in British Columbia and Alberta despite the current prolonged episode of reduced coal prices. Fortunately, almost all of these projects target metallurgical coal, for which windmills, hydro and nuclear “clean” power sources provide no substitute and in fact, on which they depend for their construction. Each of these projects will have to demonstrate satisfactory mitigation of hazards arising from potential subsidence before they will be allowed to proceed.

DMT Geosciences Ltd of Calgary, AB has recently worked with an underground mine proponent to model subsidence over an entire mine layout, in native coordinates and for multiple seam extraction, using a proprietary influence function model. Currently calibrated using a best estimate of western coal subsidence characteristics, the model itself will undergo additional calibration as monitoring data above the actual mine is obtained.

The model itself is fairly easy to use, quick to run and provides results in an easily managed format for graphical display. As well as mining subsidence, it has in the past been shown to predict surface movements due to oil and water extraction at depth. For the current project. the results obtained in the initial subsidence prediction phase have allowed areas of potentially hazardous or damaging surface movements to be determined.

Slope stability analysis and prediction based on the limit equilibrium method of Luming Molybdenum Mine's West-I and North Region

Zhi-an Huang — 2016-11-28

Slope stability is directly related to the safety of the mine production, which is one of the key factors influencing the mining production benefit. Based on China Railway Resources Group Co., LTD Luming Molybdenum Mine’s west-I and north area as the main research background, according to the slope engineering geological conditions and mining design of Luming Molybdenum Mine, this study established the numerical simulation mechanical model for the selected profiles, including three profile of West-Ⅰregion and three profile of North region, analyzed and calculated the safety factor by the limit equilibrium method and Geo-Slope software, evaluated slope stability. And optimization design was carried out on the sections not meeting the requirements, and after the optimization design, the safety factor met the requirements, the slope is generally stable.

Study on the similar materials simulation of the slope stability of the west-Ⅰzone in Luming Molybdenum Mine

Zhi-an Huang — 2016-11-28

Based on the study of geological data and rock mechanics parameters of the Luming Molybdenum Mine, and according to the slope stability in the excavation process of the weak structure of mining area, the similar material simulation test was developed. By the proportion of geometric similarity constant 300, the laboratory model was set up for 3-3 profile, and arranged with displacement monitoring points and stress monitoring points, then the excavation process of the actual slope was simulated with this model, finally the conclusion was concluded after collecting relevant data, as follows: in the process of open-pit slope excavation, the bench slope was effected by weak structural plane and excavation disturbance. And the bench slope was destroyed due to the deformation failure, especially in the cross area of the weak structure plane and fault, and the area of bench slope located in weak structural plane. This conclusion was similar to the conclusion of the FLAC numerical simulation, which proved that the similar simulation experiment conclusion was correct and dependable.

Stability and access implications of open pit mining through old underground mine workings

John G. Henning — 2016-11-28

Increasingly, mining operations are looking at developing large open pits down through old, abandoned underground workings in order to extract remnant ore left within pillar zones.

Maintaining pit wall stability while mining through major scale underground stoping zones presents both a risk and challenge that can have significant impact on overall pit economics and viability. Potential operational problems associated with the interactions between the stopes and the pit walls may occur, necessitating pit wall redesign, ground support installation and operational rescheduling. In addition, anticipated interactions of the pit shell with underground mine workings must be closely evaluated to maintain a safe working environment. Using illustrative examples, this paper discusses how operational hazards and risks to pit wall stability can be assessed and mitigated

Thermomechanical impact of Underground Coal Gasification exploitation

Farid Laouafa — 2016-11-28

Underground mining by coal combustion (Underground Coal Gasification - UCG), raise the questions of the mechanical behavior of the site and of the stability of the overburden rock layers. By studying the underground reactor, its inlet and outlet, we confirmed the key role played by mechanical damage and thermo-mechanical phenomena. Deformation or collapse above the cavity may cause a collapse in the overlying layers or a subsidence at surface level. These phenomena highly depend on the thermoporomechanical behavior of the rock surrounding the cavity (the host rocks). The numerical results presented in this paper are derived from models based on different assumptions describing a raw geological background. Several 3D and 2D nonlinear finite element modeling are performed based on two methods. On the basis of the analysis of the numerical results, we can highlight the main factors influencing the behavior and the mechanical stability of overburden and consequently the UCG process evolution.

Escapeway solutions

Allison Deadman — 2016-11-28

The requirement for secondary egress from underground workings has long been regulated in Australia. Escapeway systems have evolved from simple airleg rising ladders and timber ladders to steel galvanized ladders and more recently fully enclosed polyethylene ladders.

The polyethylene ladder - Safescape Laddertube - was introduced to the underground mining industry in 2010. It is a cylindrical, enclosed, modular plastic ladder designed for use in underground escapeways and access ways. The design of Safescape Laddertube has many advantages, one of those being that it is enclosed therefore minimizing the risk to climbers of exposure to fretting rock. In ‘standard’ installations there have been on occasion changes in the ground conditions which have resulted in significant fretting or rock burst causing deformation in the Laddertube. In addition there is on occasion a requirement to position an escapeway in ground that has highly stressed or squeezing ground conditions, presenting mines with potential for failure of ground resulting in serious damage to these escapeways.

As a result, Safescape have developed a number of proactive solutions that can be used at the time of installation which will eliminate or minimize the effects of ground that is not ‘competent’. These solutions address the need for ground support and eliminate the need for the traditional methods of ground support in a rise such as bolt and mesh, which also means we no longer need to put people in unsupported ground to complete this high risk work.

Despite being a recent development in escapeway systems, Laddertube is effectively being used in a variety of applications, meeting the specific needs of underground mines worldwide.

Estimating stope vein footwall stability using various constitutive modelling techniques

Andrew Pyon — 2016-11-28

Operating in weak narrow vein mines presents many issues in terms of ore productivity. Maintaining stable mining excavations and limiting unplanned overbreak are some of the main concerns in narrow vein mining. The use of numerical modeling became a popular method for this since it is capable of examining stress patterns and identifying rockmass failure. This paper will focus on creating a 3-dimensional constitutive numerical model for narrow vein mines that incorporate weak rockmass properties. The Case Study Mine selected is an underground narrow vein mine joining a weak material known as talc-chlorite-schist. The construction of this model will be associated with the unplanned ore dilution determined by surveyed profiles from the mine site.

Redesigning the geometry of the Makala Coal Mine to improve safety and productivity

Jean-Pierre Tshibangu — 2016-11-28

Makala is a room-and-pillar coal mine situated in the Katanga Province (DR Congo), close to the city of Kalemie (eastern part of the country). It exploits the so-named Lukuga Coal Basin which is composed by four coal seams numbered 1 to 4, but the economically mineable are 1 (about 2m thickness) and 2 (1 to 1.5m thickness). This coal basin shows some similarities with south-African deposits (Cahen 1961, in Carte Géologique du Zaïre). From West the deposit plunges towards East with an average dip of 8°. Mining operations by room-and-pillar method started in 1914 on the northwestern part of the deposit, following the outcrops of coal seams. Currently only seam 1 is being mined out and the workings are being developed southwards to avoid the higher overburden towards East. Despite the increasing thickness of the overburden, the geometry of the method does not vary, and consists in rooms of 4m wide and pillars of 8x6m, leading to a recovery of about 60%. The main gallery lays from North to South for more than a kilometer. Panels situated on the western part of the main gallery are composed with stable pillars, while on the eastern part one can observe some typical problems like pillar fracturing, ground heave and roof falls. In this last case we noticed that the roof of seam 1 is of poor mechanical quality.

In order to understand the geomechanical problems, we first built a 3D geometrical model, updating the mine layout and incorporating both geological and topographical data. This modelling has been achieved using the GEOVIA-GEMS software. The approach helped in assessing as accurately as possible the overburden to be taken into account when calculating the weight to be supported by pillars. From the defined geometry, we used the modified tributary area method (Brady and Brown 1999) to redesign the pillars accordingly. A 2D numerical modelling has been used as well to assess the stability of the roof and dimension timber support used in the mine.

Shear behaviour of regular and irregular rock joints under cyclic conditions

Seyed Mohammad Mahdi Niktabar — 2016-11-28

Rock masses often have sets of joints or fractures and almost all failures are due to the presence of these discontinuities. Natural joints have irregular surface and correct evaluation of shear strength and deformations of irregular joints are very important for analysis and engineering design of rock structures. These joints are often subjected to dynamic loads because of earthquake and blasting during mining and rock cutting. Hence, it is important correctly evaluate the shear behaviour of regular and irregular rock joint under dynamic condition. In the present study synthetic rock joints are proposed with plaster of Paris and regular joints are simulated by keeping regular asperity with asperity angles 15⁰-15⁰- and 30⁰-30⁰, irregular rock joints are proposed by keeping the asperity angles 15⁰-30⁰ and 15⁰-45⁰. The sample size and amplitude of roughness is kept same for both regular and irregular joint and it is 298*298*125 mm and 5mm respectively. Shear test have been performed on these joints on a large scale direct shear testing machine by keeping frequency and amplitude of shear load under cyclic condition as a constant and varying the normal stress. Shear strength of rock joints increases with increase in asperity angle and normal load during the first cycle of shearing. With increasing number of shear cycle, shear strength reduces for all the asperity angles but rate of reduction is more in case of high asperity angle. The test results also indicate that there is no effect of shearing cycle on shear strength of 15⁰-15⁰ rock joints on low normal stress and it is almost constant from first to last cycle of shearing. Mechanism of the shearing for regular and irregular joints is different under cyclic condition at low normal stress. Shearing and degradation of joint asperities on regular joint between loading and unloading are same, but for irregular joints are different at low normal stresses. Shear strength and joint degradation is more on the slope of asperity with higher angle on irregular joint, till two angles of asperities become equal during cycle shearing and it starts behaving like regular joints.

3D geological modelling method based on hybrid data model

Xuexi Chen — 2016-11-28

Based on comprehensive analysis on research findings of 3D geological model made by predecessors, a new method using hybrid data model is proposed to construct 3D geological model. This method takes borehole as its main modeling data source, and the modeling process includes: 1) generate triangle irregular network (TIN) adhering to the Delaunay’s law of ground surface according to borehole’s collar data, 2) down the borehole extend each triangle of TIN into generalized tri-prism (GTP) with knowledge inference rule, 3) convert GTP model into tetrahedral network (TEN) model or boundary representation (B-reps) model according to certain conversion algorithm. This mixed modeling method integrates the advantages of TIN, GTP, TEN and B-reps model. It is not convenient to update data dynamically, but easy to construct 3D geological model, carry out visualization and spatial analysis, extending applicable scope of 3D geological model. Based on the constructed 3D geological model in Central Business District (CBD),Beijing, some engineering applications including arbitrary cutting, virtual excavation design, virtual wandering and others are demonstrated, the flexibility and practicality of this modeling method is tested.

Measurement and analysis of virgin-rock temperature in Huanren Metal Mine

De-qiang Chang — 2016-11-28

With the increase of mining depth, the heat-harm in high temperature deep mine has become increasingly prominent and become a new obstacle of the development of mining in China. As a nearly one-thousand-meter-depth mine, two pitheads in Huanren Metal Mine were taken as study objects in this paper, the deep-hole temperature measuring method was adopted to determine the rock temperature, the original rock temperature was analyzed theoretically, the ventilation cooling depth, the geothermal gradient and the distribution model of the rock temperature were calculated and verified, the temperature of the deep rock was predicted, some pertinent suggestions to control the thermal hazard were put forward. The results shown that the ventilation cooling depth of this mine is 20m, the geothermal gradient of the two pitheads is 2.3 ^oC/100m and 3.6 ^oC/100m, the model of the airflow temperature agreed well with the measured values. The research in this paper can provide theoretical and technical support of heat-harm prevention and control to Huanren mental mine and other similar mines.

The tensile properties of GFRP bars at different loading rates

Wenxue Chen — 2016-11-28

In order to study the effect of loading rates on the tensile property indexes of GFRP bars, the tensile property experiments were conducted at four different loading rates by utilizing the electro-hydraulic servo universal testing machine. The experimental results show that: with loading rate increasing, the ultimate tensile strength and the ultimate tensile strain increase, while the elastic modulus almost remains constant with the average value 28.5GPa; the failure mode of specimens belongs to splitting failure and the stress-strain curves show a linear relationship. Basing on the experimental results and analyses, the loading rate of 2mm/min is recommended when conducting experiments to determine the tensile property indexes of GFRP bars.

A definition and evaluation index system of aging mines

Hui Ma — 2016-11-28

It is a inevitable process that the regional coal production is from growth to the recession and until closed because of the limited storage characteristics of coal resources. At present, the designation of aging mines is not clear, the definition of aging mine is also differ and has not form a complete system. Based on the above analysis, this paper aims to put forward the concept of aging mines, construct evaluation index system of aging mines and determine the weight of index layer by application of analytic hierarchy process (AHP) basing on the mine life cycle analysis and previous research results combination, it is expectation that the results come to be the bases of development planning determination of mining enterprises at microscopic level, and the references of long-term laws and regulations formulation for resource-based cities and even countries at macroscopic level.

Numerical simulation of thermodynamic performance in a honeycomb ceramic channel

Bo Lan — 2016-11-28

In order to understand the thermodynamic performance in honeycomb ceramic channel, three dimensional numerical simulation was carried out by using FLUENT.Effects of mass flow rate, solid heat capacity, and reversal time on temperature efficiency were investigated. Results show that with the increasing mass flow rate the temperature efficiency decreases linearly, and the pressure drop increases linearly in each half-cycle.For computed cases the effect of solid heat capacity on the temperature efficiency is ignorable. With the increasing reversal time, the temperature efficiency decreases slowly in bed heated period, and it is almost not influenced in bed cooled period.

Dust dispersion analysis based on the Rosen-Rammler Distribution Function

Haifei Yao — 2016-11-28

According to the principle of deriving mine dust distribution from the Rosen-Rammler distribution function, dust particle size distribution data at four places on the 4339 working face in Wangzhuang Coal Mine were regression-analyzed so as to get the dust particle size distribution law. The results show that in the area of 5 m away from the working face in the intake airway, the percentages of mine dust of less than 5μm, 5 to 10μm and larger than 10μm in particle size are 14.8%, 32.5% and 52.7%, respectively, with a concentrated distribution of 5 to 20μm. The size of mine dust concentrates in the range of 5 to 10μm for the transfer point, in the range of 5 to 10μm for the 50# support of the working face, and in the range of 5 to 20μm for the area of 20 m away from the working face in the outlet lane. Some corresponding dust-proof suggestions were finally put forward on the basis of the characteristic of mine dust distribution in different places.

Fuzzy comprehensive evaluation of emergency capability of port coal storage base with G1 method

Siheng Sun — 2016-11-28

In the emergency capability assessment of port coal storage base, one of the most important procedure is to determine the index weight. The AHP method has been widely applied at present, but when this method meet many factors or big problems, it’s easy to appear that the judgment matrix is difficult to meet the requirement of consistence and hard to further divide into groups. In this paper, G1 method, a kind of method needless to test its consistence, is adopted to calculate the index weight of each factor in evaluating emergency capability of port coal storage base. Then according to the index weight and point of each factor, get the result of the emergency capability level of base. Finally, according to the evaluation results put forward the improvement suggestion. Result shows that when the number of index is numerous, using the G1 method can reduce the amount of calculation obviously. And the G1 method is easy to operate.

Study on external protective system of waterproofing refuge chamber in Guilaizhuang gold mine

Shengnan Ou — 2016-11-28

Refuge stations, which have positive impact on facilitating escape for those miners trapped underground by a fire, explosion or rock collapse, need further perfection and research as respect to waterproofing function at present in China when in case of mine floods. A waterproofing refuge station, which designed for surviving 50 miners for at least 96 hours, along with its waterproofing, airtight, and other essential requirements has been proposed in Guilaizhuang gold mine in Shandong province according to practical situation under mine. Focusing on its external protective system of the water-proof refuge station, critical items (water-proof door, bulkhead, and lining included) were systematically presented in the paper. Some specifics, like exhausting and draining under water, were also take into consideration in the research. Accordingly a waterproofing evacuation unit, emergency evacuation unit, and emergency drainage unit were designed. Tests and simulation results indicated that the refuge station behaving good positive pressure maintenance, air-tight property, and water-proof performance.

Hazard detection and comprehensive control technologies of the integrated resource coal mine goafs in China

Wen Li — 2016-11-28

The problem of goafs disaster has become a major puzzle for the resources integrate coal mines in China. Based on the analysis of goafs disaster types and characteristics, the hazard detection and comprehensive control technologies were systematically put forward. The technologies including the goafs hazard detection technologies combined ground survey and undermine detection; the goafs risk classification and assessment technologies combined risk degree classification, qualitative and quantitative evaluation; the goafs disaster monitoring technologies combined local monitoring, regional monitoring, monitoring joint undermine and surface; the goafs comprehensive control technologies combined open stripe, grouting and roof caving on surface or undermine; the goaf safety guarantee technologies combined matching funds, policy support and administrative supervision. The results showed that the goaf disaster was divided into four types according to the disaster forms in resources integrates coal mines, that is, the abandoned old goafs or pit shaft permeable, goafs fire including coal combustion and gas explosion, the poisonous and harmful gas in goafs emission, the adverse abnormal geological disaster. The goafs have the characteristics of unknown distribution, different kinds of disaster types, concealment and happened suddenly, unpredictable, etc.. The control principles were summarized and put forward, including ground survey in advance, undermine detection follow up, hazard assessment and evaluation in time, monitoring and supervisory in place, comprehensive control for disaster reduction, safety measures for guarantee.

Multi-bed type oxidation reactor applied to the coal mine ventilation air methane

Weifeng Zou — 2016-11-28

The utilization of coal mine ventilation air methane played an important role in saving energy, reducing pollution, improving the safety in coal mine production and adjusting the energy structure. The thermal flow-reversal reactor is one of the main technologies of ventilation air methane utilization which is at a critical stage of industrial application. The thermal flow-reversal reactor of MEGTEC company and designed by some Chinese scholars were used a two-bed type generally. However, the gas who was detained in oxidation chamber and reversal valves will not enter the combustion chamber but through the chimney into the atmosphere directly when switching the flow direction, the average oxidation rate of reactor will be reduced due to the residual gas.

In order to solve the problems including low oxidation rate of methane, pressure build-up of main fan and high failure rate of valves in existing two-bed type oxidation reactor of coal mine ventilation air methane, an innovative structure with multi-bed type oxidation reactor has been designed. The paper analyzes the unique advantages of multi-bed type oxidation reactor by elaborating on the working principles of three-bed and five-bed type device. In the design of the oxidation device for industrial demonstration projects, the device whose processing capacity is 100000 m³/h adopts the five-bed type structure from the aspects of methane oxidation rate, waste heat utilization effect, cost and so on, the thermodynamic calculation process of regenerative chamber as the core unit of the oxidation device is described in this paper.

The technology has an industrial demonstration project whose reactor uses a five-bed type design located in Chongqing Songzao Datong No.1 mine. This project can produce superheated steam 64800t and reduce emissions of CO₂ equivalent 107000t annually, the excellent energy-saving and emission reduction benefits should be obtained in the project.

Water disaster investigation and control in coal mine of Southern China

Qing-hua Liang — 2016-11-28

The number of coal mines in Southern China was the possession of more than 60% of the total coal. This area was a large undulating terrain, and the terrain was so complex that the exploration was very difficult. The water damage had a great effect on southern mines. They were mainly threatened by the karst water and the goaf water. This thesis studied by mining geophysics and its methods, which were able to fit the characteristics of karst regions. Use those methods, we could detected and determined the location, size, distribution, and water-filled situation of geological anomalies that was closely related to mineral water disasters. Based on the characteristics of the mine on geology, water damage, mine drainage, this thesis studied the prevention and control measures for coal mine features in southern China to carry out scientific governing for mine water damage.

The lifting and separating system for ground maneuvering rescue equipment

Yu-kun Gao — 2016-11-28

At present, the research of our country specific emergency system of ground maneuvering rescue equipmenthas not been carried out, the field of mine special rescue equipment is still lack of specific lifting and separating facilities. To solve the above problems, this study innovatively designed the Lifting and separating system matching with the ground maneuvering rescue equipment. The design of the Lifting and separating system mainly includes four aspects in this study, such as the Lifting control room, Lift arm material section, size of telescopic boom and the Selection of hydraulic cylinder for telescopic boom. This study uses ANSYS to do research and analysis. In the process of mine rescue, this system can enhance the economic and flexibility of hedge facilities, improve the technology of mine safety emergency rescue in China, it also has important economic value and social significance for enterprises.

Safety and stability of the maneuvering rescue platform

Yu-kun Gao — 2016-11-28

With the continuous development of the mine rescue works, the various rescue mechanical equipment has been growing tendency of complexity and automaticity, which raise higher requirement to the safety, stability and carrying ability of the platform foundation. In response to these requirements, firstly the study designed the overall layout of the maneuvering rescue platform equipment. On consideration of the load arrangement rationality of the rescue platform, the humanity and convenience of the on-board equipment function and the safety of the electric device, the overall layout of the vehicle was divided into two units: the device unit and the control unit. After completing the overall layout design, the security and stability of the platform was verified and analyzed in this study. The calculation and analysis results proved that the design of the maneuvering rescue platform met the requirements for the stability and safety of the mine rescue mission and it can be quickly deployed over a long distance with suitable mobility and carrying capacity.

The performance optimization experiment of a wet high-frequency vibrating grid

Ying-hua Zhang — 2016-11-28

Dust preventing is of great significant in mine safety production. The wet high-frequency vibrating grid is one of the most efficient dedusting systems. Therefore, optimizing the dedusting parameter of wet high-frequency vibrating grid is meaningful in dust controlling. Two of the most important part of wet high-frequency vibrating grid are spray dedusting system and vibrating grid filtration system. This study optimized these two systems respectively to obtain the influence of various factors on the two systems by using the method of orthogonal experiment and then chose two factors which have the greatest impact on comprehensive optimization. The results can be used in mine dedusting practice, to reduce the incidence of pneumoconiosis and improve work efficiency.

Borehole docking system design for underground refuge chamber and ground maneuver rescue equipment

Ying-hua Zhang — 2016-11-28

Aiming at the problems of poor efficiency and low efficiency that arise during borehole docking process of ground equipment and refuge chamber in emergency refuge system, a borehole docking system is designed for the ground maneuver rescue equipment in this study. The system mainly includes three parts which are bottom hole docking device, orifice docking device and docking fixation device. Bottom hole docking device is inside the refuge chamber which is designed for three lines: food transmission pipe, air pressure pipe, power and signal transmission line; the orifice docking device is mainly for fast docking of ground equipment and emergency rescue vehicle, and external protection sealing device is designed to protect orifice docking device from harsh environment outdoor; the docking fixation device is the connecting fastening core of the borehole docking device, safeguarding system functions to achieve such as air pressure, power transmission and food supply and so on. Through field test, the system runs well after the docking of emergency rescue vehicle and refuge chamber. Air pressure, water supply and power transmission run smoothly. The operation of monitoring and control, personnel positioning system is normal. The borehole docking system met the needs of the refuge chamber. It enhanced flexibility and economy of mine refuge facility.

Use of the Analytic Hierarchy Process in safety control of rescue equipment

Ying-hua Zhang — 2016-11-28

The ground maneuver rescue equipment is complex, so it needs to carry out systematic analysis and risk assessment of the whole maneuver rescue equipment, get the relevant weight, and refer to the relevant information. Through this evaluation method, the conclusion can be obtained. It provides positive guidance and reference for the management and maintenance of the equipment system.

At present, many countries adopt the risk matrix method to assist the decision-making of an important affairs and the safety control of important system. The possibility and importance of the important factors in the development of the transaction are related. This method can be used to link the possibility and importance of the important factors affecting the development of the transaction, and stratify the data. It also has a good effect on the system in which objective judgment is not strong. This study refers to the mature evaluation system in the field of abroad car production, combines the actual rescue situation of Fengfeng District in Jizhong Energy Group, and aims to establish a subjective evaluation system with special characteristics of underground emergency refuge system. This evaluation system uses the method of scoring combing weight, and combines the analytic hierarchy process. It provides a scientific basis and effective reference for daily use and maintenance of the entire system.

Research on new high-water solidified materials to reinforce coal and eliminate gas outburst

Ying-hua Zhang — 2016-11-28

As coal and gas outburst is one of the main mine disasters, it is very important to prevent and eliminate the coal and gas outburst. Grouting setting liquid into coal can strengthen the coal seam, increase rigidity coefficient (f), and reduce expansion energy of gas. According to the related experimental procedures of cement paste, experiments on the performance of complex materials that high-water material added with different admixtures were carried out. Results showed that: as the increase of water-cement ratio (W/C), the mobility and setting time were all increased, but compressive strength and rupture strength were declined, furthermore, high-water material showed early strength, which can reach 80% of 14 days compressive strength when it is 7 days. As a rapid setting and early strength cement, Na₂SiO₃ had the best effects on shortening setting time, when dosage was 3% , the initial setting time and the final setting time were 13min and 21min shorter than blank samples, while the compressive strength increased more than 2 times. As retarder, the initial setting time can extend to 83min when compounding with tartaric acid of dosage of 0.4%. Through the orthogonal experiment the best additive ratio was determined, which was W/C=2, tartaric acid with dosage of 0.2%, Na₂SiO₃ with dosage of 3%, bentonite with dosage of 12%. Reinforcement simulation experiment showed that, grouting radius of new setting liquid was 250mm when grouting pressure was 60KPa, 7d rupture strength and compressive strength were 5.2MPa and 6.4MPa, and were 37% and 88% higher than ordinary high water material, which was effective for reinforcing coal and eliminating gas outburst.

Key technologies for extinguishing large-area goaf fires in closely spaced shallow coal seams

Botao Qin — 2016-11-28

The large spontaneous combustion fire in the goaf of the 22305 fully caving face at the Bulianta coal mine in north-western China was examined. The cause of spontaneous combustion in the goaf of closely spaced shallow coal seams was analysed. To deal with the problem of significant air leakage combined with a large fire area and a hidden fire source that could easily re-ignite, a proposed set of key techniques for extinguishing goaf fires was put into practice. This mainly included sealing the air leakage cracks, high-flow injection of liquid nitrogen, and infusion of a large quantity of foam inhibitor. The results showed that these measures rapidly extinguished the goaf fire, lowering the CO concentration from 43,051 ppm to ＜ 25 ppm and reducing the temperature in the goaf to about 20°C. The 22305 face was subsequently safely reopened and quickly put back into production within three months.

The assessment of emergency capability of coal mines based on AHP-fuzzy comprehensive method

Shu Jiao Tong — 2016-11-28

In order to improve the emergency management capability to prevent or control the major accidents, it is significant for the coal mine to study the method on assessment of the emergency capability. This paper is aiming at bring about an analytic hierarchy process (AHP) and fuzzy comprehensive method to assess the emergency capability of coal mine. Firstly, the key elements of the emergency management for coal mine were analyzed based on the theories of the emergency management. And then, from the precaution, response and recovery aspects, the assessment index system of the emergency management capability for coal mine was built and the basic indexes of each element were confirmed and discussed too. Furthermore, a multi-level fuzzy comprehensive evaluation model for mine emergency management capability was built based on the AHP (Analytic Hierarchy Process) and fuzzy mathematics. Also, the assessment index system and mathematical model were applied to a selected mining enterprise, whose assessing result was “high”, some shortcomings of the emergency system of the coal mine were analyzed and some suggestions were proposed to improve the emergency capability for the coal mine. The study is helpful for the emergency management and prevention of major accident of coal mine.

Study on local temperature controlling technology and equipment in heat disaster coal well

Haijun Wu — 2016-11-28

Along with continuous increasing of coal resources mining depth, high temperature and heat disaster is becoming more and more serious. In that case, the health of workers under coal well is threated at any time. Coal resources safe mining is impacted seriously. In order to eliminate coal well heat disaster, scholars at home and abroad have inputted a lot of time and energy. They researched controlling theory of coal well heat disaster. They developed cooling equipment of high temperature. They have achieved some results. But the equipment is too large in which result, it is hard to move. The power of the equipment is high. So, it cost large amount of electric power. The maintenance cost is huge that the coal could not afford. In a word, application effect is not ideal.

Based on this, the article analyzed the influence factors of coal well heat disaster firstly. Then, the calculation method of cooling load in coal well was researched. The author put forward the technology of local high temperature controlling. ZLS-90 movable cooling equipment was developed successfully which includes refrigeration compressor, evaporator, water cooling condenser and expansion valve etc. The property of compressor plays an important part in cooling effect of whole system. After comparing, we choose GEA bock compressor. Enthalpy difference comprehensive testing system was used to test the performance of the equipment. Test results show that all performance index comply with the designing requirements. The property is also stable.

The paper also proposed discharging heat with heat-rod to deal with the heat of condensation as well as using the heat synthetically. By means of local temperature controlling technology and equipment, we can carry out effective cooling. In that case, the working environment under coal well would be guaranteed, safety production of coal well would be guaranteed. It would realize efficiency, conservation and environmental protection of resource.

Effect of forming technology on oxygen supply performance of oxygen candles in refuge spaces

Jian-guo Liu — 2016-11-28

For a more stable and reliable oxygen supply from an oxygen candle in a refuge space, the forming technology of oxygen candles was investigated in this study. Chlorine was found in the wet pressing process, revealing that dry pressing has better forming effect on oxygen candles. Three types of oxygen candle blocks (OCBs) were pressed through dry pressing at pressure-application speeds of 0.1, 0.3, and 0.5 kN/s, respectively, for a pressing time of 10 min. From compression strength and combustion experiments, the ultimate compressive strengths (UCS) obtained for the three OCBs were 3.83, 5.48, and 5.83 kN and the stability coefficients of oxygen production (SCOP) were U₁= 0.966,U₂= 0.724, and U₃= 0.770. From the results of these experiments and observation of combustion residue of OCBs, it was found that the stability of oxygen production decreased when the pressure-application speed within an appropriate pressure range was increased.

Experimentation on a new type of mining emergency rescue relay cabin

Jie Shen — 2016-11-28

By comparison with existing hedging facilities, this study designed an innovative mining emergency rescue relay cabin with respect to function, service object, structure, size, and system components. The structures and systems of the emergency rescue relay cabin were designed and implemented and an air-tightness test indicated a test chamber relief rate of 26 Pa/min, which meets the requirements. Further, an airsleeve air supply test conducted indicated an air supply rate of 220 L/min, which is sufficient for the staff replacing the equipment in the emergency rescue relay cabin. The total air supply volume was 9680 L, which can be supplied via two bottles of 40 L, 15 MPa compressed air.

Chemical equipment failure probability correction model based on the Multi-layer Grey Evaluation Method

Yue Zhang — 2016-11-28

The basic leak probability about chemical equipments cannot be distinguished the influence of many factors on the failure probability in petrochemical field. Due to the defects, in this study, by applying Analytic Hierarchy Process (AHP) and introducing grey theories, the chemical equipment failure probability correction model based on multi-layer grey evaluation method was proposed. At the same time, by applying AHP, six 1st level indicators including safety management, production equipment, process, production environment, natural environment and personal quality were analyzed, as well as analyzing twenty-seven 2nd level indicators. The importance of various influencing factors in the chemical equipment failure system was obtained. Then according to grey system theories to calculate its correction factor value, and applying the correction coefficient to correct the failure probability. By taking the vinyl chloride tank of a chlor-alkali company as an example, through calculation and analysis, the results indicated that the corrected factor value of failure probability for the tank was 3.335, the correction coefficient was 1.25, and the actual failure probability of the tank was larger than the basic leak probability. It provides a new way to the failure probability correction, and has a theoretical significance and practical value on accurate calculation of the quantitative risk evaluation.

Mechanisms and applications of formatting unsafe behaviour motivation

Yuebing Zhang — 2016-11-28

To reveal the mechanism of safety production behavior, and effectively curb various unsafe behavior, based on the analysis of safety production behavior features, applying need, motivation, behavior theory of psychology, adopting the logic analysis method and accident cases analysis, analyzes various motivation of unsafe behavior, and the source of need which produce the motivation. The results show that, need is the source of human behavior, to improve the level of people's safety needs, and appropriately reduce the level of other needs are the basic measures of preventing the unsafe behavior. While the main means to adjust the level of needs is to regulate the sense of lack and imbalance of corresponding conditions, such as "on-the-spot accident meeting" can enhance the lack and imbalance senses of people’s safety conditions, and improve the level of safety need.

Examining safety and sustainability in longwall coal mining through case studies of disasters and reviewing global trends in environmental stewardship

Ben de Wit — 2016-11-28

Longwall mining is a method of underground coal mining that is common in many regions worldwide, however, it is uncommon and relatively new to the mining industry in Canada. The coal mining industry in Western Canada is familiar with various types of surface operations, however, recently a number of operations have been closed, or placed on Care-and-Maintenance, due to poor market conditions and profitability. In spite of these low prices however, the industry is seeing the potential development of longwall underground coal projects which seem to present an opportunity for mining that can be more economical and sustainable relative to surface operations.
This paper identifies and examines current and historical longwall underground coal projects and what makes them successful financially, economically, and socially. The topic of safety is a primary focus in the analyses, with recent and historical coal mining disasters highlighted, and operational challenges addressed. The paper also includes a summary of the root cause analyses that can serve as a risk register to highlight significant issues and challenges for operating a longwall coal mine in Canada, and can potentially be used to help educate a local workforce so that future operations in Canada are both safe and sustainable.
The paper discusses sustainability within the coal mining industry and the effects longwall operations could have on Canada’s future. The current technologies utilized in Longwall operations provide opportunities to safely and economically mine coal resources in Canada, and future advances in longwall technology could drastically reduce accidents, lost time injuries, and fatalities. However, the method, and coal mining in general, is also examined for long term sustainability and suitability when considering the global trend of increasing environmental awareness and responsibility, and the reduction of fossil fuel consumption, particularly coal.

Research on safety incentive model of coal miners and strategy analysis

Qinggui Cao — 2016-11-28

Based on the safety incentive theory and safety incentive mode,the system dynamics model of safety incentive for coal miners is established, and the simulation of the model is provided. The research shows that the effect of improving reward measure and environmental conditions arethe most significant. According to the influence to the safety incentives, other measures are in the following order: technical equipment, safety culture, enterprise goals and punishments. The safety incentive strategy of coal miners is put forward with the simulation results.

A new Virtual Reality training system for underground coal mines

Hui Zhang — 2016-11-28

Virtual Reality (VR) technology in mining is a new field of research. The successful application of VR to mining is critical to mine safety and production. Based on different input/output devices that are used in the VR system, the current VR mining system can be divided into three types: screen-based general system, projector-based customized system, and Head Mount Display (HMD)-based intuitive system. Based on a VR headset, a smartphone and a Leap Motion, an HMD-based intuitive VR training system was built and tested by 10 students who tried both the HMD-based system and a normal screen-based system to experience the difference between the two systems. The results showed that the HMD-based system can give better user experience, and is easier to use. In future, with more intuitive input devices employed, and improved system software, the VR training system for mines could play a much more important role in mine training.

Study of roadside packing to go with gob-side entry retaining technology on crisp surrounding and blasting face in the Xinzhuang mine

Yage Li — 2016-11-28

In order to improve the recycle rate of coal resources, extend the service-life of the mine, and alleviate the tensions of excavation-replacement in the Xinzhuang mine, this paper presents a high-water material for roadside packing to go with gob-side entry-retaining technology on crisp surrounding rock and blasting working face. Based on the conditions in the field, the authors analyzed the utility of the filling structures of the 12011 machine roadway. On the basis of engineering analogy method and laboratory experiment, the authors determined the ZKD new high-water material ratio of each component and the filling process parameters. This research shows that when four conditions are met—rectangular packing is used; water cement ratio of the new high-water material is 1.8:1; the Φ 18 mm × L 3400 mm anchor bolt is imbedded in the filling body; and supplementary support, which consists of anchor bolt, wire rope, and steel beam, is applied—the average contraction rate of the roadway section is 13.38%, achieving a more satisfactory effect. Compared with gob-side entry driving, it can improve the indirect profit by 9.86 million yuan; compared with digging a new roadway, it can increase the profit by 5688.5 yuan per meter.

Optimization of bit nozzle parameters of reverse circulation sampling used in coal mines

Jianning Kang — 2016-11-28

The coal mine air reverse circulation sampling technique is important to improve accuracy of direct determination of gas content. Sampling drill is an important structural element to realize the coal mine air reverse circulation sampling technique. Embedded annular ejector and external nozzle of the drill are the main structures that can realize reverse circulation. External bit nozzle divide the mine compressed air into two parts. One part is used to wash the drill hole for preventing the hole collapse, the other part can press cuttings at the hole bottom into the drill pipe center tube and provide the transmission power. Bit nozzle dip angle and position are studied by numerical simulation, and the results are proved by the filed test. The research results show that when the dip angle of nozzle is 15 °, the position is appropriate away from the drill cutter, it can make better reverse circulation, and increase the sampling depth, improve the quality of sampling, prevent damage of drill bit and buried drill accidents.

Electrical equipment certification in Canadian underground coal mines – problem solved?

Ronald F. King — 2016-11-28

Certification of electrical equipment for underground coal mines in Canada is problematic. EX protected electrical distribution equipment to Group 1 standards is not manufactured in Canada, and even if it were, there is no facility in Canada which is accredited to certify it. The Canadian Federal laboratories previously tasked with the job are closed. Provincial regulations require certification by either a now-defunct facility or by the US authorities (MSHA). Unfortunately the underground coal legislation in the US is significantly at odds with Canadian Provincial legislation and equipment approval requirements which presents problems with equipment certified there.

Although the underground coal mining industry in Canada is small, the western Provinces are blessed with substantial resources of high quality steel-making coal, much of which can only be accessed by underground mines. There are perhaps half a dozen large underground projects awaiting a price revival in Alberta and British Columbia, and it was the authors’ experience at one of these projects which lead to this paper.

The project in question was owned by a Chinese company which wanted to use Chinese electrical distribution equipment certified in China to IEC equivalent standards. The process of convincing the Provincial regulators that the Chinese equipment was safer than the equipment which would be allowed under Canadian standards was arduous but ultimately successful. The next step was to seek changes in the Canadian electrical standard applicable to mines so that the benefits could be felt across the country. This has recently also been accomplished.

This paper examines the problem through an important aspect of electrical safety in underground coal mines - protection against electric shock and arcing. It compares the requirements of the Canadian legislation, US and UK legislation and IEC standards used by other countries.

It concludes that the levels of safety against shock and arcing afforded by IEC-certified multi-point systems can be orders of magnitude better than the single point systems mandated or traditionally used in Canada. Additionally, multi-point systems may be better suited to protect high voltage equipment beginning to be deployed in large open pits than the current Canadian protection standards. The recommendations arising for changes to Canadian standards await ratification, and we are hopeful that they will be adopted by Provincial regulators as soon as practicable.

Improving shovel safety using SAFEmine’s situational awareness technology

Marco de Werk — 2016-11-28

Mining operations involve ~~a lot of~~ risks that can be controlled through engineering and process control. The human factor; however, is extremely difficult to ~~protect against~~quantify and control. Best practices, proper rest, and a good work/ life balance contribute to safer operating conditions, but there is no way of predicting when an employee has a bad day. Impacts of external stresses that are beyond the control of the employer can be minimized by implementing safety technology such as Hexagon Mining’s ~~theSAFEmine~~ SAFEmine collision avoidance system. Technology is another layer of protection, but it does not give the desired outcome without proper implementation, business processes, and continuous effort to improve. Aecon has successfully completed a pilot project with the SAFEmine system and has committed to operating a 5500 shovel and supporting dozer with the system. This paper aims to outline the process and results obtained during the pilot project.

An evaluation of Soma underground coal mine disaster with respect to risk acceptance and risk perception

H. Sebnem Duzgun — 2016-11-28

The underground coal mine disaster occurred in Soma-Eynez Mine (SEM), Turkey, is one of the largest coal mine disasters of this Millennium. A sudden mine fire started in the mine cannot be controlled and resulted in 301 fatalities and approximately 100 injuries. Although the cause of the fire has not been determined yet and there are various hypothesis related to the ignition of the fire, most of the casualties are mainly due to decision-making related problems in various hierarchal levels. Moreover, the decision making related problems in the emergency management have cascading effects and impact on the casualties, which are related to risk acceptance and perception of the mine management. In this paper, the casualties of Soma Mine Disaster (SMD) are analyzed in terms of risk acceptance and risk perception in order to establish related guidelines for better decision-making practice in case of emergencies in underground mines in Turkey. It is found that quite a high degree of risk is accepted to be taken for mine fires by the high level decision makers, which led mine employees to have a false safety perception. This also resulted in almost full ignorance of self-escape, inappropriate use of personal safety equipment and unstructured emergency management which yielded large number of mine staff to wait in the mine during the fire instead of a sharp implementation of the mine evacuation plan.

From operational hazards to organizational weaknesses: Changing the focus for improvement

Georges Loiselle — 2016-11-28

The daily operations in the mining industry are still a significant source of risk with regard to occupational safety and health (OS&H). Various research studies and statistical data world-wide show that the number of serious injuries and fatalities still remains high despite substantial efforts the industry has put in recent years in decreasing those numbers. This paper argues that the next level of safety performance will have to consider a transition from coping solely with workplace dangers, to a more systemic model taking organizational risks in consideration. In this particular aspect, lessons learned from the nuclear industry may be useful, as organizational learning processes are more universal than the technology in which they are used.

With the notable exception of major accidents, organizational performance has not received all the attention it deserved. A key element for reaching the next level of performance is to include organizational factors in low level events analyses, and approach management as a risk control system. These factors will then appear not only in event analysis, but in supervision activities, audits, change management and the like.Many recent event analyses across various industries have shown that organizational factors play a key role in creating conditions for triggering major accidents (aviation, railway transportation, nuclear industry, oil exploitation, mining etc.). In the following paper, we will present a perspective that may be used in supervisory activities, self-assessments and minor events investigations. When ingrained in an organizational culture, this perspective has the highest potential for continuous safety improvement.

Risk management in the mining sector through complex systems

Maria Sameiro Q. Domingues — 2016-11-28

Related to complexity there is a wide diversity of concepts. What the Santa Fe Institute (USA) calls “systemic” corresponds to what Morin (Morin, 2006) calls “complex” until there is a unified terminology (Mariotti, 2000). When understanding complex and complexity, then complexity can be perceived as a fabric (what is woven together) of heterogeneous inseparably associated constituents (…) (Morin, 2006). According to different authors main drivers of complexity can be found in human behaviour and uncertainty. This complexity, structural or dynamic can be organizational, technological or nested in their relationship. The complex interrelationship that exists between individuals within an organization or project and its influence on competitiveness can be studied by individual’s emotional intelligence and organizational behaviour (Love, Edwards, and Wood, 2011).

According to ISO 31000:2009, risk management “refers to a coordinate set of activities and methods that is used to direct an organization and to control the many risks that can affect its ability to achieve objectives”. When concerning any sector, industry, services, project or activity, it requires the use of models or theories as guidelines. Therefore when its basic elements comprehend human behaviour and/or uncertainty, risk management in order to be effective and adapted as much as possible to reality, must be operational within complex systems, as already demonstrated in different R&D environments. Risk management faces particular challenges when approaching specific needs, such as the mining sector. The ILO convention (C175, 1995) concerning Safety and Health in Mines, establishes “that workers have a need for, and a right to, information, training and genuine consultation on and participation in the preparation and implementation of safety and health measures concerning the hazards and risks they face in the mining industry”, and furthermore recognizes “that it is desirable to prevent any fatalities, injuries or ill health affecting workers or members of the public, or damage to the environment arising from mining operations”. In this context, risk assessment of integrated operations can be improved by complex risk models and dynamic environments (Grøtan et al., 2011).

Hence, complex systems can provide decision makers a supporting tool comprising a three axis analysis model. Each of the three axis (X, Y and Z) comprehends a multi-variable linear function f i: X: f_1 (management variables related to mining); Y: f_2 (variables related to risk management systems) and Z: f_3 (variables related to complex systems). Such a proposal, designing, developing and testing a risk management decision making model within complex systems, transversal to other hazard sectors of al economic activities, may provide organizations with sustainable and integrated risk management indicators.

Application of Cognitive Task Analysis in mining operations

Serenay Demir — 2016-11-28

Through the advancement of human-machine interactions in various fields, understanding beyond the technical components has become prominent. The field of cognitive engineering focuses on the most efficient interaction between machines and human as a whole. It is considered to be a large area of study, which requires extensive research in every aspect. In this sense, traditional methods for analyzing human behavior in a work setting, which mostly centralize in identifying material and observable traits, are in need of improvement for the sake of a well-designed project. The concept of Cognitive Work Analysis (CWA), in this regard, has gained interest in academic and business settings in the last few decades. The fact that cognitive task analysis expands the observation of worker’s interactions to a more cognitive and behavioral level makes it a more sophisticated tool for many scholars. Taking this into account, this research essentially aims to fully comprehend the five steps of CWA through cases and finally, seeks for possible applications in the mining industry, where it is most needed. In this paper, a CWA framework that can be used in mining industry is developed, based on a previous model for quantifying human error in maintenance for a more generalized industry.

Keywords: cognitive work analysis, work domain, human behavior.

Avoiding workplace accidents: The importance of pre-job safety analyses

Colin Morrish — 2016-11-28

Careful, thorough, individual and group pre-job safety analyses completed by knowledgeable and competent individuals can significantly reduce workplace incidents. Benefits include: decreased costs, improved productivity and morale of employees, and an increased perception by those outside of positive safety consciousness.

Pre-job safety analyses can be done either by a team of workers or by a solitary worker. In both cases these workers need to be trained in the completion of pre-job safety analyses. Supervisors must check to see that these analyses are completed competently.

Examples of pre-job safety analyses presented will be the Neil George Five Point Safety system and a construction field level risk assessment. Workers may be guided by one of these systems to complete a pre-job safety analysis but must also have access to safe work procedures, and equipment and area inspection reports.

Examples of accidents that I investigated during my 18 years as a Saskatchewan mine inspector will be discussed within the context of the above. The causes of the accidents will be explored with close reference to how pre-job safety analyses could have prevented their occurrence.

Notification systems and risk management

Maria Madalena Antunes — 2016-11-28

In an occupational context, “Notification” understood as “the act of telling someone officially about something, or a document that does this”, (in Cambridge Advanced Learner’s Dictionary & Thesaurus), may reveal a management approach. The ILO Code of Practice on Recording and Notification of Occupational Accidents and Diseases provides practical guidelines for establishing and use a national system for recording and notification of occupational diseases.

In the European Union, there is a legal obligation to report occupational accidents and diseases. Such is the case, e.g. with RIDDOR making reporting certain incidents a legal requirement. The report informs the enforcing authorities about deaths, injuries, occupational diseases and dangerous occurrences. Mandatory notification procedures may also arise from certain types of specific hazards, such as exposure to biological agents.

Also relevant are reporting procedures in non-compulsory management systems, namely the ILO Guidelines on OH&S management systems, when considering performance monitoring and measurement, clearly states that “Reactive monitoring should include the identification, reporting and investigation of: (a) work-related injuries, ill health (including monitoring of aggregate sickness absence records), diseases and incidents(…)”.

Findings from a case study over a 5 year period, based upon a notification system from one organization alone comprehending 736 records and 915 workers directly involved, supports a main conclusion. A notification system is not by itself enough in prevention terms. The validity of the required information and the way it is demanded is also fundamental to obtain the best adequate records. The statistical data treatment is a critical stage, for changes regarding preventive actions and measures are based upon such findings and conclusions.

Statistical treatment of data is fundamental to achieve adequate use of the data collected. Multiple correspondences analysis privileges tables of relevant size comprising simultaneously variables of distinct nature: quantifiable and qualitative and it helps in describing the complex relationships that may exist among variables, both independent and dependent (Dohoo, 1996).

The mentioned study comprises a total of 47 management variables and a set of multiple sub-variables, resulting from the notification system analysed. The results obtained identify management variables that may be considered transversal to other economical sectors, from the workers’ point of view (gender, professional classification and others) and specific to the sector if the employers’ point of view is considered (day of the week, type of accident, communication procedures, contributive factors, (…)).

This study aims to design, implement and validate notification system as both a transversal and sectoral information system in OH&S risk management. A notification system should provide effective and adequate flow of information within a proactive prevention context.

Full-scale fire experiments in an underground mine

Rickard Hansen — 2016-11-28

Few full-scale tests have been performed in underground mines and the information needed to validate calculations and estimations cannot fully be provided during the preventive work, risk mitigation as well as the incident planning. This paper comprises two full scale fire experiments involving a loader and a drilling rig respectively in a mine drift in mid-Sweden. The heat release rate in the fire experiments was determined through oxygen calorimetry, i.e. by measuring the mass flow rate, gas concentrations and temperatures at certain heights at the far end of the mine drift – downstream of the fire source - where the fire experiments were conducted. The resulting heat release rate curve of the loader fire displays a fire that is dominated by initially the sudden increase when primarily the first tyre is engulfed by flames and then by the slowly declining heat release rates of the large tyres of the vehicle. The calculated peak heat release rate of the loader was 15.9 MW and occurred after approximately 11 minutes from ignition. The resulting heat release rate curve of the drilling rig displays a fire with high heat release rates and relatively short lived – compared with the fire in the loader. Practically all the combustible items were ignited in the early phases of the fire. The calculated peak heat release rate of the drilling rig was 29.4 MW and occurred after approximately 21 minutes from ignition. The fuel load of the loader consisted mainly of the tyres, the hydraulic oil and the diesel fuel. The fuel load of the drilling rig consisted mainly of the hydraulic oil and the hydraulic hoses. The calculated heat release rate curves were controlled by comparing the summed up energy contents of the participating components with the integrated heat release rate curves.

Diesel exhaust exposures in an underground mine

Hugo Coulombe — 2016-11-28

The mining industry is a major contributor to the Quebec and Canadian economy. In Canada, more than 400,000 workers are involved directly or indirectly in the mining industry. Health and safety challenges in underground mines are unique regarding the complexity of the environment. Exposure to diesel engine exhaust is a major concern in underground mines due to the presence of off-road diesel-powered machinery. Diesel engine exhaust has been linked to cardiopulmonary diseases and was classified as a human carcinogen by the International Agency for Research on Cancer in 2012. Here we present the results of a preliminary study conducted in an underground gold mine in the province of Quebec in 2014-15 to assess diesel engine exhaust exposures among mine workers. The goal of this study was 1) to compare three surrogates of diesel engine exhaust exposure (total carbon, elemental carbon and respirable combustible dust) and 2) to assess diesel exhaust concentrations among the similar exposure groups and the variability of the exposures. Results were also compared to the Ontario and Quebec occupational exposure limits for compliance purposes. Environmental and breathing zone measures were taken. Average environmental results of 0.31 mg/m³ in total carbon, 0.24 mg/m³ in elemental carbon, and 0.17 mg/m³in respirable combustible dust were obtained. Average breathing zone results of 0.32 mg/m³ in total carbon, 0.19 mg/m³ in elemental carbon and 0.36 mg/m³ in respirable combustible dust were obtained. Highest exposures were obtained in the conventional, scooptram and jumbo workers. The average total carbon/elemental carbon ratio was 1.3 for environmental measures, and 1.9 for breathing zone measures. The variability observed in the total carbon/elemental carbon ratio shows that interferences from non-diesel related organic carbon can skew the interpretation of results when relying only on total carbon data. More data is needed however to support this.

Liquid-solid coupling analysis of tailings dam under complex engineering conditions

Shuren Wang — 2016-11-28

The tailings pond is a necessary facility for maintaining normal production of a mine as a place for stockpiling tailings. On the other hand, the tailings dam is a major danger for metal and nonmetal mines, because dam failure may occur. We take the flat land tailings pond of the Sanshan Island gold mine, Shangdong Province, China, as an example. The tailings dam 3D numerical model was built using MIDAS/GTS and FLAC^3D techniques. The safety factor and the potential slide face of the tailings dam were calculated under different conditions using the strength reduction method. It is concluded from the liquid-solid coupling analysis that there are three potential failure modes of the tailings dam under preloading. Under the present conditions, the tailings dam meets the safety requirements, whereas it does not in the event of additional heaping. So the height of the present heap must be cut to satisfy the stability requirements under the condition of rain infiltration.

Numerical analysis of Westwood Mine tailings embankment stability during the restoration phase

Yaya Coulibaly — 2016-11-28

Stability analysis of Westwood Mine tailings embankment performed using SLOPE/W and SIGMA/W codes showed that the minimum factor of safety obtained is higher than the recommended value of 1.5 set by some authors and the Quebec Ministry of Natural Resources and Wildlife for static loading and steady flow conditions. Pore pressures that must be controlled are higher in bottom layers of the embankment and these pressures move toward the downstream side. In addition, low electrical resistivity values (by geophysical method) associated to the high water content tailings layer, suggest its susceptibility to internal erosion.

Application of an economy comparison model for mine cooling system technology

Miao Dejun — 2016-11-28

Being the existing complex selection method of mine cooling scheme and the incomprehensive index value,etc., with the specific circumstances of the high temperature mine, the paper put forward 13 index values, including the machine power, project investment, operation cost, etc,. established comparative model of technical and economic benefit of mine cooling system by using the objective entropy weight and TOPSIS method. Using objective entropy weight, the entropy weight of evaluation index and the weight decision matrix are determined, using TOPSIS method . the ideal solution and the negative ideal solution are determined . Using the closeness degree calculation the scheme sort, then the optimal scheme can be determined . To four cooling schemes in a mine, optimization calculation and comparison of are carried out by the model, scheme 4 is the optimal scheme for cooling system.

Behaviour of cable bolts in shear: Experiment and mathematical modelling

Naj Aziz — 2016-11-28

The application of cable bolts for ground support is on the increase in underground coal mines worldwide. Currently, two methods of evaluating the performance of the cable bolt are favoured; the short encapsulation pull test and shear test. The former method can be used both in the laboratory and the field while the latter can be undertaken mainly in the laboratory. There are two methods of shear strength testing, single and double shear tests. This paper examines the double shear testing of several cable bolts currently marketed in Australia under various pre-tension stresses. Both plain and indented wire cable bolts were tested. It was found that the shear strength of the cable bolt was a function of the wire geometry and initial pre-tension. Indented wire cable bolts were lower in shear strength than the plain wire cable bolts. A mathematical model was proposed to evaluate the shear strength of cable bolts using Fourier series and a linear relationship between shear and normal loads. The model coefficients were determined based on the experimental results. The findings from the mathematical modelling tallied well with the experimental results.

Operating conditions of a mine fan under conditions of variable resistance

Ying-hua Zhang — 2016-11-28

According to the basic fluid principles and ventilation laws, combined with the ventilation network computing method, this study proposed the concepts of relative sensitivity and absolute sensitivity, and studied this two sensitivities’ variation law under the conditions of variable airway resistance. The result showed that: when the airway resistance increased, the fan air volume, its relative sensitivity, absolute sensitivity and fan pressure’s relative sensitivity, absolute sensitivity tend to decrease. At the same time, fan pressure showed a trend of increase. On the contrary, when the airway resistance goes down, those parameters’ change tends to be an opposite trend. Research conclusion can provides basis and guidance for adjusting the fan operation condition in mine production process.

Analysis of slag debris flow initiation based on laboratory tests of slag

Hongbiao Zeng — 2016-11-28

Accumulated slags and waste in mines are major physical resources for slag debris flow, which is a potential major disaster threatening mines safety. Initialed by the heavy rain, slag debris flow has happened in Ganjaing gully around Luanchuan county, China. Studies have been carried out for a further undersdanding on the formation and initiation mechanism of the slag debris flow. Slag samples with different fines content are collected from the gully and the slag strength and permeability have been investgated by direct shear tests and falling head permeability tests respectively.The results indicate that the fines content has a significant impact on both the strength and permeability characteristics of slags. With the fines content increasing, both the strength and the hydraulic conductivity of the slag decrease. And the strength of saturated slag samples is extremely weak, meaning that water will easily soften the slag. In addition, as the fines content increases, the hydraulic conductivity would decrease acceleratedly to a quite small constant. Based on the current invsestgation, it can be concluded that two different types of slag debris flow would form in the specific conditions, the shallow debris flows are mainly dominated by surface erosion, while the deep debris flows by bottom tearing and suffusion erosion, respectivily.

Hydrogeological challenges and strategies at McArthur River Operation

Xiaoyou Yun — 2016-11-28

High pressure, radon bearing water has been identified as one of the most critical challenges in mining the high grade uranium deposit at the McArthur River Operation, Cameco Corporation. The ore deposits are located between 490 m and 640 m below the surface and surrounded by water bearing Athabasca sandstone, a graphitic fault zone, and highly altered ground. This paper introduces the inflow risk management program at McArthur River Operation which includes various hydrogeological challenges and the corresponding strategies applied, such as risk based probe and grout programs (geological, hydrogeological, and geotechnical), ground freezing programs, and comprehensive ground control programs. These programs have being developed, tested, and proven successful over years of mining practices. Working with this world class deposit of high risk and low tolerance, the authors believe that these experiences might be beneficial to other mining operations with similar hydrogeological characteristics.

Experimental study on bolt pull-out property coupled by plate and shotcrete

Xiliang Liu — 2016-11-28

Based on a self-developed multi-function bolt mechanical test system, axial pull-out loads were applied on same bolts under the different conditions, combining with flat plate, butterfly plate, new-type plate and three kinds of shotcrete(C15, C20 and C25 plain concrete). Experimental results showed that the relationship between bolt elongation and drawing force has three stages, including elastic, yielding and strengthening. The strength of shotcrete lining has obvious influence on the bolt stiffness during the elastic stage i.e. the strengthening of the concrete leads to the increase of bolt stiffness. The strength and width of the yield platform of the bolt reach the maximum for butterfly plate and yield plate with C20 plain concrete lining. Butterfly plate and new-type plate both have yield functions, and the latter one can effectively prevent the damage of shotcrete. The damage of shotcrete lining usually begins around of drill holes, when the interfacial stress between the initial shotcrete lining and surround rock is higher than that in the initial lining and secondary lining. With the new-type plate used, the cracks in the secondary lining cut through along the same direction.

International Advisory Committee and Editorial Board

Editorial Staff — 2016-11-28

International Advisory Committee and Editorial Board

Front Matter

Editorial Staff — 2016-11-28

Front Matter

3rd International Symposium on Mine Safety Science and Engineering

Preface

Mathematical model for gas diffusion from non-homogeneous coal particles

Permeability prediction for coal reservoirs and reconstruction of a different scales pore-fractures network

Quantitative risk assessment on large-scale oil depots of opencast coal mine

Development and realization of a coal and gas outburst simulation device

The distribution and origin of hydrogen sulfide abnormal enrichment coal mines in China

Accumulation pattern of groundwater containing Hydrogen Sulfide in the southern Junggar basin in China

Application research on gas drainage technology at low permeability coal seam

Influence of temperature on gas desorption-diffusion laws of coal particles

Numerical simulation of gas migration tule in mining-induced fractures field

Methods of measuring the effective drainage radius of 3# coal seam in Huoerxinhe coal mine

Temperature variation of coal during the gas adsorption process

Statistical analysis of coal mine accidents in China from 2005-2013

Analysis of coal crack and permeability characteristics slotted by water jet and the effect on gas outburst

Research on the negative pressure distribution law and its application for boreholes in coal seam bedding gas extraction

﻿﻿﻿﻿﻿﻿﻿Mathematical simulation and experiment of CBM detection

Numerical modelling and rescaled range analysis on spontaneous combustion under surface methane drainage in a Chinese coal mine

The strength properties of fibre glass dowels used for ground control in coal mines

Numerical simulation for propagation characteristics of outburst shock wave and gas flow when outburst prevention facilities fail

Influence of fundamental internal parameters to low-temperature critical temperature in coal self-ignition process

Experimental study of negative pressure gas drainage influences on coal moisture content

The laws of gas-solid coupling of coal-bed gas in deep high gassy coal seams

Grey Correlation Model of influence factors analysis of ventilation time in single-way tunnel

Numerical research on the airflow distribution in mine tunnels

Application of a ventilation management program for improved air quality

Numerical study of simultaneous methane and coal dust dispersion in a room and pillar mining face

Reducing heat stress exposure in mines

Effect of hydrogen on explosion of methane-air mixture

Drilling escape and rescue system in Wangjialing coal mine

Effects of immediate roof thickness on lower sub key strata movement in ends of large mining height panel

Study on the performances of a protective door in coal permanent refuge havens

Numerical modelling of the goaf: Methodology and application

A coal enterprise scientific-technical progress evaluation system based on the Internet

Simulation of strata behaviour laws of a coal mine in Jungar Coalfield

Goaf area exploration in Anjialing surface mine based on the C-ALS

Application of the strength reduction method in coal mine roof support design

Numerical simulation of the migration laws of supports and surrounding rock for coal seams of large dip angle

Theoretical analysis of support stability in large dip angle coal seam mined with fully-mechanized top coal caving

Theoretical research on roof damage of the fully mechanized top-caving mining coal seam with deep dip angle

Characteristics of acoustic wave velocity variation in the process of deformation and failure of loading coal

Numerical simulation technique for gateroad stability analysis under fractured ground condition

Organizing Committee

b-value as a criterion for the evaluation of rockburst hazard in coal mines

Quantitative evaluation of stope damage induced by seismic waves

Influence of weak planes on rockburst occurrence

A model of rockburst including geological dynamic conditions and mining

Rockburst experiences in Cheves Hydropower Project, Perú

Rockburst mitigation experiences on underground projects in the Cheves Hydropower project in the Peruvian Andes

Destress blasting on the border of safety pillars

Powered support selection for longwall workings in dynamic load conditions

Evolution of grouting methods for dynamic supports in broken ground

Large scale panel destress blasting parametric study

Improving ground control safety in deep vein mines

Numerical investigation of EDZ development around a deep polymetallic ore mine

Estimating the probability of unsatisfactory performance associated with the instability of mine developments

Numerical modelling of time-dependent skin degradation of an isolated pillar

Quantitative analysis of haulage system instability in deep hard rock mines using numerical modelling

Minimum strength required for resisting cyclic softening/failure of cemented paste backfill at early age

Analysis of failure in a salt room and pillar mine

Lessons in slope stability management from Kinross’ Tasiast mine, Mauritania

Effect of buttress on reduction of rock slope sliding along geological boundary

Validation of empirical rock mass classification systems for rock slopes

Application of InSAR for monitoring deformations at the Kiirunavaara Mine

Modelling the impact of particle flow on rigid structures: Experimental and numerical investigations

A versatile model for the evaluation of subsidence hazards above underground extractions

Slope stability analysis and prediction based on the limit equilibrium method of Luming Molybdenum Mine's West-I and North Region

Study on the similar materials simulation of the slope stability of the west-Ⅰzone in Luming Molybdenum Mine

Stability and access implications of open pit mining through old underground mine workings

Thermomechanical impact of Underground Coal Gasification exploitation

Escapeway solutions

Estimating stope vein footwall stability using various constitutive modelling techniques

Redesigning the geometry of the Makala Coal Mine to improve safety and productivity

Shear behaviour of regular and irregular rock joints under cyclic conditions

3D geological modelling method based on hybrid data model

Measurement and analysis of virgin-rock temperature in Huanren Metal Mine

The tensile properties of GFRP bars at different loading rates

A definition and evaluation index system of aging mines

Numerical simulation of thermodynamic performance in a honeycomb ceramic channel

Dust dispersion analysis based on the Rosen-Rammler Distribution Function

Mathematical simulation and experiment of CBM detection