Experimental Research on Permeability of Coal and Rock Mass considering Postpeak Failure

In most mining areas of China, coal seams are characterized by low gas pressure, poor permeability, and high adsorption capacity, all which have brought considerable difficulties to seam coalbed methane (CBM) extraction. According the multiyear scientific research production practice is migrated in quantity only after body directly mined, surrounding rocks deform fracture under influence. Thus, key effective control migration CBM comining technology lies investigating resolution, permeation, migration, accumulation laws unloading confining pressure during mining. The MTS815.02 rock mechanics testing system its supporting equipment combined test permeability characteristics mass (postpeak fractured sandstone specimens) loading using steady method, then, permeation obtained. Results show that postpeak crack propagation reaches a stable state, gradually increases, presents an approximately linear reduction; phase, opening coalescence degree cracks increase as deformation extends. peak value. strain softening phase follows, where closed declines certain extent. Moreover, step size has bearing on permeability. Specifically, decreases, change increases stability.