岩体应力与渗流的耦合及其工程应用

岩体中应力与渗流的耦合对于工程应用十分重要。应用孔隙弹性力学理论，研究裂隙岩体与多孔介质岩体的应力变化引起的渗透性变化。推导出应力与渗透系数的关系式，得出由于多孔介质含水层疏水及应力变化造成的地表下沉计算公式。基于孔隙弹性理论，开发用于耦合应力与渗流的有限元计算软件。采用有限元方法耦合应力与渗流的关系，模拟不同采宽条件下采煤工作面的采动影响特征，得出工作面围岩渗透性变化、覆岩破坏高度、地表下沉与工作面几何参数的关系，这对于类似条件下的煤矿开采与设计有指导意义。

COUPLED BEHAVIOR OF STRESS AND PERMEABILITY AND ITS ENGINEERING APPLICATIONS

Changes in permeability due to stress variation in fractured porous rock media have important impacts on engineering design. Therefore, it is of vital importance to couple stress and fluid flow effects when dealing with practical engineering problems. For example, when mining near an aquifer, the mining-induced stress redistributions cause changes in the inherent permeability, which may result in water intrusion into the mining workings. In this paper a modified cubic law is adopted for a fractured media, and stress-aperture-permeability relationships are derived in a three-dimensional domain by using stresses and matrix-fracture interactive model. In the porous portion, permeability is to a great extent controlled by the pore geometry, which is a function of the applied stress. A model has been developed to determine the three-dimensional stress-permeability relationship, assuming that the solid grains in the porous medium are the cubical grain packing structure. Surface subsidence induced by mining and drainage in porous aquifers is also studied using poroelasticity. A finite element model incorporated with coupled stress and flow in fractured porous media is developed. The model is then applied to examine permeability changes, strata failure, and surface subsidence in a coal mine for different mining geometries. The results show that the permeability around the mining panel increases as the length of mining increases. Also surface subsidence depends not only upon the thickness of mining, but also upon the pore pressure withdrawal. The simulated results are in good agreement with the observed data.