A damage evolution permeability model of porous media based on Rice's poroelasticity theory

Focusing on ground subsidence, fissures, and rapid drawdown of groundwater levels induced by coal mining, this study investigates the groundwater seepage patterns throughout the mining process in the Ningtiaota Mine, through a combination of physical simulation experiments and theoretical analysis. The main conclusions are as follows: (1) The full-process seepage experiment reveals a three-stage evolution of groundwater flow: from pore flow to fracture flow and then to turbulent flow, which aligns with the three-stage characteristics of shallow overburden failure and reflects the transformation of fluid flow during overburden destruction. (2) Based on Rice's theory, a permeability evolution equation for the entire process of rock failure was established by accounting for permeability changes induced by porosity variation <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mi mathvariant="normal">Δ</mml:mi> <mml:mi>n</mml:mi> </mml:math> and two abrupt jumps in permeability following rock failure. This was achieved by introducing new parameters such as the permeability jump coefficient <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mi>ξ</mml:mi> </mml:math> .(3) The permeability evolution curve of sandstone throughout the damage process is driven according to the derived equation. Comparison with experimental results shows good agreement, validating the rationality of the proposed model.