地下厂房围岩渗控效应精细模拟与评价

我国西南地区河谷深切,坝址区地貌及地质条件复杂,地下厂房的位置往往离库区较近,水库蓄水后,地下厂房围岩渗流特性将成为影响工程安全和正常运行的重要因素之一.为减小厂区渗漏并改善厂房围岩的渗透稳定性,工程设计采取防渗帷幕、排水孔幕和排水廊道等渗流控制措施.采用子结构、变分不等式和自适应罚函数相结合的方法(简称SVA方法),开展了牙根二级水电站厂区整体三维渗流场分析,评价了厂区围岩渗流控制方案的合理性,并论证其优化的可能性.研究结果表明:厂区防渗排水系统的渗流控制效果显著,防渗排水系统设计方案总体上是合理、有效的;厂区上部排水系统对于以库水渗漏为主的渗流控制不起作用,高高程排水孔幕的间距可适当放宽;厂区副排水孔幕对减少厂区各洞室渗漏量、降低厂区围岩孔隙水压力并改善围岩的稳定性具有显著作用.

Elaborate Simulation of Seepage Control Effects on Surrounding Rocks of Underground Powerhouse

The construction sites of hydropower stations in Southwestern China are typically characterized by deeply-cut valleys and difficult geological conditions,and the underground powerhouse is commonly located nearby the reservoir. The seepage flow behavior in the surrounding rocks of underground caverns isone of the most important factors which may affect the safety and operation of the hydropower station. In order to reduce the seepage flow rate out of underground opening and improve the resistance of surrounding rocks to seepage failure,a seepage control system including grouting curtains,drainage hole arrays and drainage tunnels is designed. This study focuses on the performance assessment and optimization design of the seepage control system for YagenⅡunderground hydropower system. The numerical method combining a substructure technique,the variational inequality formulation of Si-gnorini’s type and an adaptive penalized Heaviside function（short for SVA method）is adopted.Numerical results demonstrate that：the seepage control system is properly designed and can effectivelylower the phreatic surface in the surrounding rocks;the upper part of the drainage system has little effect on controlling the leakage from reservoir, and hence the spacing of the drainage hole arrays at higher elevations can be enlarged;and the auxiliary drainage hole arrays play an important role in both reducing the leakage into the underground caverns and the pore water pressure in the surrounding rocks and improving the stability of the surrounding rocks.