A simulation study on stress-seepage characteristics of 3D rough single fracture based on fluid-structure interaction

Abstract

This paper expounds on the process of deformation and seepage field change of single coarse fracture under normal stress and puts forward a numerical simulation framework based on fluid-structure coupling method to reasonably link contact deformation of fracture surface with seepage field change. The geometric model of a three-dimensional rough single fracture surface with controllable JRC is established based on the random surface generation method. The numerical test model of radiation flow of single fracture in rough rock is constructed, which is consistent with the laboratory test. Through carrying out numerical simulation tests of different JRC and normal stress conditions, this paper discusses the phenomenon and intrinsic nature of the influence of JRC on fracture seepage characteristics. The increase in eddy current intensity and eddy current area ratio is the inherent characteristics of the seepage field characteristics after JRC increases. With the rise of energy loss, the macroscopic seepage flow decreases. In addition, with the advantage of the fluid-structure interaction method, the fracture deformation characteristics under different normal stresses are reflected by the ratio of the contact area. The correlation among fracture surface deformation, velocity vector, and seepage pressure are analyzed. Finally, the cubic polynomial correlation between gap width ratio and contact area ratio is established and verified. It is of positive significance to quantify the influence of coarse single fracture contact ratio on deformation-seepage coupling characteristics under normal stress.