STUDY ON MODEL OF DAMAGE AND FLOW COUPLING IN BRITTLE ROCK FAILURE PROCESS
脆性岩石破裂过程损伤与渗流耦合数值模型研究

Experimental results provide strong evidence that rock permeability cannot be a constant but a function of stresses and stress-induced damage. In this paper, a numerical code Rock Failure Process Analysis (F-RFPA2D) is implemented by introducing a flow-stress-damage (FSD Model) coupling model for heterogeneous rocks and taking into account the growth of the existing cracks and the formation of new fractures. In this FSD model, material is discribed by many elements with the same size and different mechanical and permeability parameters in order to reflect the heterogeneity of rock. The water fluid pressure during failure process is obtained by flow and stress coupling iteration. A coupling analysis of flow and damage under hydraulic fracturing on rock is attained to simulate the fracture process of rock, and this model has been used to investigate the behavior of fluid flow, damage evolution and their coupling action in samples subjected to both hydraulic and biaxial compressive loading. Two numerical simulations are given. The results of the first simulation suggest that the nature of fluid flow in rocks varies from material to material and the peak strength of the rock samples and the change of rock permeability during progressive failure process depend strongly upon the heterogeneity of the rocks, and the numerical results compare well with the corresponding experimental results. Another simulation result presents a failure process subjected to tensile stress caused by pore pressure. It shows that the FSD model is valid by comparing with the experimental results.