Study on the Formation Mechanism of Seepage Network in Fractured Rock Mass Under the Coupling of Hydromechanical Process

Water inrush disasters caused by fractures are frequent in geotechnical engineering today, gradually becoming a bottleneck to underground engineering development. Various natural processes result in many fractures of different sizes in the rock mass. The inherent concealment and complexity of geological strata preclude direct observations, leading to a limited understanding of the permeability characteristics of fractured rock formations. Therefore, a hydroelectric power plant is selected as the case study. PFC2D and data regression analysis methods are used to carry out numerical calculations of fracture seepage and establish an assessment model. The research results reveal the formation mechanism and distribution of the seepage network of fractured rock under the hydromechanical coupling and establish the statistical regression analysis model of fractured rock porosity. The main conclusions are as follows: (1) The different morphology of fractures leads to the division of fractures into water‐blocking fractures and seepage channels. However, the seepage channel is discontinuous due to the mutual cutting of water‐blocking fractures and seepage channels. (2) Under the coupling of the hydromechanical process, the hydraulic conductivity of the fracture decreases exponentially with the increase of the fracture angle and maximum principal stress and decreases linearly with fracture residual length. (3) The fracture dip angle, lateral pressure coefficient, fracture residual length, and time are selected as the influencing factors to establish the statistical regression analysis model, which provides an effective analysis method for accurate evaluation of engineering stability.