Fluid-Solid Coupling Model of Equivalent Continuous Medium in Overburden Rock Based on FLAC~(3D) and Its Application

Due to the importance studying the seepage law of overburden rocks,an equivalent permeability coefficient for overburden rock is deduced using the cubic law,in which the strain is considered as a parameter.Based on FLAC3D,an equivalent continuous medium numerical model in overburden rock is established considering the fluid-solid coupling effect and the program with FISH language is used to achieve the calculation of equivalent continuous medium numerical model.The results indicate that the increasing permeability zones in the overburden rock hshow a M-shaped distribution in the roof and W-shaped distribution in the floor in initial stages of coal seam mining.The conductive fracture formed when the two increasing permeability zone is intersected with the increasing permeability zone of the lower roof.The pore pressure changes periodically in the aquifer it will reach the maximum value when water burst takes place and then decreases rapidlly.So the equivalent permeability coefficient taking the strain as a parameter can describe the seepage law of the overburden rock stratum exactly.