Full-scale fire experiments in an underground mine

Abstract

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.