Effects of immediate roof thickness on lower sub key strata movement in ends of large mining height panel
Abstract
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.References
Feng, G., Wang, X. and Kang, L. (2008). Analysis on the mechanism of the face contacted blocks structure in overlying strata above the longwall face. Journal of China Coal Society, 01:33-37.
Fu, Y., Song, X., Xing, P., Yan, G. and Li, Z. (2009). Stability analysis on main roof key block in large mining height workface. Journal of the China Coal Society, v 34, n 8, 1027-1031.
Huang, Q. (2005). Study on loading distribution law on key roof and its structure upon mining face under thick sandy layer. Journal of China University of Mining and Technology, v 34, n 3, 289-293.
Huang, Q. and Zhang, P. (2004). Study on dynamic load distribution on key roof blocks of under thick sandy soil stratum. Chinese Journal of Rock Mechanics and Engineering, v 23, n 24, 4179-4182.
Jiang, D. (2015). Research on Overburden Structure and Shields Stability of Fully Mechanized Top Coal Caving Mining Face with Large Mining Height. Henan Polytechnic University, 19-21.
Ju, J., Xu, J. and Wang, Q. (2011). Cantilever structure moving type of key strata and its influence on ground pressure in large mining height workface. Journal of China Coal Society, 12:2115-2120.
Kong, L., Jiang, F., Liu, J. and Wang, C. (2010). Relationship between Support and Strata in Extra-thick Coal Seam Fully-mechanized Sublevel Caving Mining based on High Precision Microseismic Monitoring Technology. Chinese Journal of Geotechnical Engineering, 32(3): 401-407.
Qian, M. and Miao, X. (1995). Theoretical analysis on the structural form and stability of overlying strata in longwall mining. Chinese Journal of Rock Mechanics and Engineering, 02:97-106.
Qian, M. and Xu, J. (1998). Study on the “O shape” circle distribution characteristics of mining-induced fractures in the overlaying strata. Journal of China Coal Society, 05:20-23.
Shen, J., Meng, D. and Wei L. (2011). Study on the structural system of roof in fully mechanized top coal caving. Applied Mechanics and Materials. v 90-93, 2041-2044.
Song, Z., Jiang, J., Sun, X. and Zhao, J. (2002). The structure model and its application to roof rock pressure control in gateways of a deep mine. Mining Science and Technology '99, 9-14.
Syd S. Peng. (2013). Coal Mine Ground Control. China University of Mining and Technology Press, Xuzhou, pp. 310-312.
Syd S. Peng. (2011). Longwall Mining. Science Press, Beijing, pp. 131-138.
Wang, J. and Wang, Z. (2015). Stability of main roof structure during the first weighting in shallow high-intensity mining face with thin bedrock. Journal of Mining and Safety Engineering, v 32, n 2, 175-181.
Wang, J., Yuan, Y., Tu, S. and Li B. (2014). Roof structure characteristics in fully mechanized coalface with large mining height and reasonable loading of support. Journal of Mining and Safety Engineering, v 31, n 4, 512-518.
Wu, F. (2014). Study on the Law of Roof Broken and Instability and the Control of Mining Height Fully Mechanized Mining in Thick Coal Seam. China University of Mining and Technology, 9-12.
Yang, P. and Liu, C. (2012). Structure forms of basic roof and reasonable supporting parameters in ends of fully-mechanized top caving face. Journal of Mining & Safety Engineering, 01:26-32.
Yang, S. and Jiang, F. (1999). Research on the relationship between sublevel caving support load and roof structure. Chinese Journal of Rock Mechanics and Engineering, 18(3): 287-290.
Yang, Z. (2008). Instability behavior for roof strata in shallow seam longwall mining. Journal of the China Coal Society, v 33, n 12, 1341-1345.
Yuan, Y., Tu, S., Zhang, X. and Li B. (2015). Dynamic effect and control of key strata break of immediate roof in fully mechanized mining with large mining height. Shock and Vibration, v 2015.
Zhang, Q., Jia, H., Fan, L., Zhao, X., Wang, Z. and Xing, J. (2013). The detection research of roadway roof strata structure in coal seam. Advanced Materials Research, v 734-737, 677-681.
Zhu, D. and Qian, M. (1987). Numerical simulation of destruction and instability of basic roof in long wall face. Journal of China University of Mining & Technology, 16(3): 1-9.
