Study on outburst sensitive indexes of No.3 coal seam in Xinjing mine

Abstract

Coal and gas often extrude when excavating the No.3 coal seam in Xinjing mine, the impact indexes can be summarized as follows: geological structure, coal block texture, burial depth, gas pressure, gas content, coefficient of coal seam sturdiness, initial velocity of gas emission and comprehensive indexes. On the basis of field observation, testing qualitative and quantitative methods, it found that impact indexes include interlayer micro-slide, closely spaced joint, minor faults, coal seam epigenetic scour, coal seam fold, etc. The geological structure is decisive indicators. No.3 coal seam belongs to Ⅲ class, Ⅳ class, class deformation coal, and coal block texture is decisive indicators. The critical value of burial depth is 400(meter). By analyzing the gas pressure of No.3 coal seam, the result shows that the minimal critical value of gas pressure is 0.74. The gas content could be gained through calculation formula, taking minimum 0.33 as the critical value of coal seam sturdiness coefficient, and the maximum 10.20 as initial velocity of gas emission. The No.3 coal seam belongs to anthracite, the comprehensive indexes are D(0.25) and K(20). Therefore, it suggested that study of outburst sensitive indexes will contribute to outburst prediction and treatment measures selection of coal and gas outburst.