Spatial-temporal Evolutional Laws Of Mechanical And Seepage Characteristics Of Coal Under Mining-induced Condition

Spatial-temporal evolutional laws of mechanical and seepage characteristics ofcoal under Mining-induced condition is the core technology of "coal and gas safetymining ". This paper takes15th coal seam of10th mine Pingdingshan Coalmine Groupas the object, experimental study and numerical simulation are used to analysis thespatial-temporal evolutional laws of mechanical and seepage characteristics of coalunder Mining-induced condition, respectively. The experimental study of mechanicalproperties of coal containing methane was performed on coal samples in No.10Mine,Pingdingshan Coal Mining Group Corporation Ltd. under different loading-unloadingconditions which are loading axial pressure while unloading confining pressure. Theresults show that mechanical properties of coal containing methane under differentloading-unloading conditions are different. Solid-gas coupling model which coulddescribe the skeleton deformability of coal containing gas and the compressibility of gasunder the solid-gas interaction condition was built. Then we got following preliminaryconclusions:①The permeability of coal specimen first decreases and then increases withincreasing axial strain during the complete stress-strain; coal specimen under thecondition of loading-unloading, the permeability of coal sample suddenly increasedbefore reached peak strength, and then decreased slightly, then again increase rapidly incoal specimen destruction paragraph.②Strength of loading-unloading coal decreases exponentially with the increasingof initial axial force, strength decreases with increasing in axial pressure loading speedwhich presents the power function relationship, it decreases exponentially with theincreasing of initial confining pressure, it decreases with increasing in gas pressurewhich presents the linear relationship③Solid-gas coupling model which could describe the skeleton deformability ofcoal containing gas and the compressibility of gas under the solid-gas interactioncondition was built. The numerical simulation results show that the model described thereal environment appropriately.④First we made excavation on the three-dimensional model based on the physicalparameters of PingDingShan tenth coal mine to obtain the stress distribution of coalseam after excavated instead of easy uniform loading. Then we simulated the gas drainage from boreholes based on constructed mathematical model. We got gasmigration rule and coal seam permeability evolutional laws. The numerical simulationresults show that the model described the real environment appropriately.