Comparison of outburst hazard of coal with different failure types: a case study

Abstract

ABSTRACT Coal and gas outburst, usually takes place in tectonic soft coal areas. It is generally difficult to obtain soft coal samples, which influences the accuracy of outburst hazard determination of coal seams and thus poses a severe threat to the safety production of coal mines. Taking the outburst accident of Chensilou Coal Mine which was previously identified as no outburst risk as an example, comparison and analyses were made on outburst parameters, size distribution characteristics and microscopic pore structure of these coal samples with various failure types. Results suggest that coal samples with different destruction degrees exhibit consistent microstructure and macroscopic behaviors. The critical gas pressures corresponding to primary hard coal, tectonic coal and post-outburst coal are 1.25 MPa, 0.64 MPa and 0.52 MPa, respectively. Based on the particle size distribution of tectonic coal, the primary hard coal was adopted to simulate the tectonic soft coal. The critical gas pressure of the simulated coal sample is 0.66 MPa which approaches the condition of actual tectonic coal, which can improve the prediction accuracy. Hence, this method can make up the loss brought by unreasonable sampling and enhance the accuracy of outburst hazard determination of coal seams.