Damage and oxidation characteristics of coal pillar in upper working face of contiguous coal seams
In order to study the influence of contiguous seams mining on the damage and oxidation characteristics of coal pillar in the upper working face,taking the 74201 working face in Bailu Coal Mine as the research background,the influence of lower working face mining on the plastic distribution and oxidation characteristics of upper seam coal pillar was analyzed by the means of numerical simulation and experimental research.FLAC3D simulation results show that,with the advance of 4-2 coal seam,the failure and deformation characteristics of the upper seam coal pillar can be approximately divided into three stages:intact coal pillar,fractured coal pillar with basic continuity,and broken coal pillar with large scale shear failure.According to the temperature programmed test results,the critical temperature points of CO and C2H4 are 10~20℃ lower during the secondary oxidation process,and the maximum oxygen consumption rate is 2573.1×10-11 mol/(cm-3·s)higher;C2H2 is not detected in intact coal pillar,while that is detected in the fractured coal pillar and broken coal pillar at 250℃ and 240℃,respectively,which indicate the crushing process of coal pillar promotes the secondary oxidation of coal,and the broken coal pillar is more prone to spontaneous combustion than the intact.Finally,it was concluded that,the risk of spontaneous combustion of the broken and unstable coal pillar in the upper coal seam increases with the lower coal seam mining.
spontaneous combustion of coalcontiguous coal seamcoal pillar crushingsecondary oxidation