Permeability characteristics of rock masses incorporating nonlinear flow behaviors in discrete fracture networks
SUN Yicheng1, WEI Yufeng1, HU Shuhan2, QIN Xingzhou1
(1. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu, Sichuan 610059, China; 2. Yunnan Construction Investment First Survey and Design Co., Ltd., Kunming, Yunnan 650500, China)
Abstract：To address the limitations of traditional linear seepage theory under complex fracture conditions, a novel rock mass permeability coefficient is introduced. This model integrates the empirical advantages of the Izbash equation with the theoretical framework of the Forchheimer equation. Based on the geological conditions of the Huanglong Pumped Storage Power Station project, a three-dimensional fracture network model was developed using the Monte Carlo stochastic method. Through numerical simulations and in-situ borehole water pressure test data, this research systematically examines the interaction mechanisms among fracture geometric characteristics, network connectivity, and nonlinear seepage behavior. The results reveal the following: (1) A distinct exponential relationship exists between the seepage parameter p and the water permeability rate q. Complete fracture network connectivity is achieved when p＞8.65, which is accompanied by a significant reduction in permeability anisotropy. (2) For p＜4.28, the effective seepage area decreases by 71.3%, with a maximum velocity reduction of 76.21%. (3) Compared to conventional empirical formulas, the proposed model enhances the calculation accuracy of rock mass permeability coefficients in medium to high permeability conditions (1–30 Lu) by incorporating a non-Darcy flow effect factor E. This innovation demonstrates superior performance in characterizing inertial effects and local vortex energy dissipation mechanisms.
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2025, Vol. 44 
