Fluid–Solid Coupling Based on a Refined Fractured Rock Model and Stochastic Parameters: A Case Study of the Anti-Sliding Stability Analysis of the Xiangjiaba Project

The anti-sliding stability analysis of a high concrete gravity dam under a complex geological condition is a difficult problem to solve. To depict the discontinuous characteristics of a dam foundation fractured rock mass in a numerical model, a multi-scale coupling 3D geoengineering modelling method is presented. Facial-based geometric models of rock strata and fractures are established with the NURBS-based B-Rep and then coupled together after being converted to the voxel-based model based on TEN. Using the partial differential equation method, the interaction of fluid and solid is realized. Thus, the plastic zone and pore water pressure distribution are obtained. The results show that the plastic zone is formed in some fractures, and the dam stability against sliding of this cross section is diminished. Because of the existence of interlaced fractures, the potential sliding surface may be produced once the fractures are connected. Considering the complex geological structures in a dam foundation, the spatial variability and uncertainty of the rock mass parameters cannot be ignored. The random field of the elastic modulus is generated and applied to the fluid–solid interaction. The range of the plastic zone is different when the elastic modulus is assigned a logarithmic random distribution. The proposed methods in this paper improve the stability analysis by enhancing the finite element numerical modelling by considering discontinuities of the rock mass and simulating the random distribution of the elastic modulus, which has significant application value for other projects.