(1. State Key Laboratory of Water Resources and Hydropower Engineering Science，Wuhan University，Wuhan，Hubei 430072，China；2. Central Southern China Electric Power Design Institute，CPECC Group，Wuhan，Hubei 430071，China)
Abstract：To reduce the seepage of the underground opening in Shuibuya hydropower project and improve the seepage stability of the surrounding rocks，a seepage control system including grouting curtain，drainage hole array and drainage tunnels is designed and deployed. The long-term seepage control effects of the surrounding rocks of the underground powerhouse are performed by a stationary seepage analysis method combining the variational inequality formulation of Signorini¢s type with an adaptive penalty Heaviside function to guarantee the numerical stability and convergence. Meanwhile，the difficulty in finite element mesh generation is reduced and the calculation time and modeling accuracy are balanced with a global model of equivalent modeling and a submodel of accurate modeling for drainage hole array. Intuitive criteria for assessment of the reasonability of the numerical results are established，namely stationary seepage free surface in any homogeneous medium must be continuous，smooth and can not be return-curved，unless it intersects with an interface between two media of distinct permeabilities. By making comparison with the measurements of pore water pressures in the surrounding rocks，the feasibility and effectiveness of the proposed model are demonstrated. The reasonability of the design of the seepage control system and the possibility of its further optimization are illustrated. The research results are helpful for optimization design of the seepage control system in similar projects.
