中文摘要：

在建的锦屏一级水电站蓄水后坝基(肩)软弱岩体在高水头作用下的弱化效应是工程建设十分关心的问题。为揭示这种弱化效应,提出一套岩体水压弱化效应的试验研究方法:采用岩体形成过程–力学条件模拟,力学参数控制三轴压缩全过程试验的手段制备岩体试件,对岩体试件进行现今天然状态与1~4 MPa静水压力的系列三轴压缩试验(围压为5,10,15,20,25,30 MPa)。试验结果及分析表明,在浅部低应力岩体中弱化效应十分显著,强度参数中的内摩擦因素f的弱化程度在13%以内,c的弱化程度随静水压力的升高而急剧增大,最大可达100%;变形模量的弱化程度在20 MPa围压以下随静水压力的升高而增大,随围压的升高而减小,围压达到20 MPa后则基本无弱化现象。同时,建立了不同静水压力工况下岩体力学参数预测模型。这些成果已在锦屏一级水电站工程建设中得以应用,研究方法为岩体力学性能的试验室研究开辟了新的有效途径。

英文摘要：

The weakening effect of high water head on dam foundation weak rock masses after impoundment for Jinping I hydropower station is a highly concerned subject for its engineering construction. A series of testing methods are suggested to reveal the weakening effect. Based on a geological process-mechanical mechanism simulation-mechanical parameter control theory,rock mass replica specimens can be prepared with complete process of triaxial compression test and used for hydro-mechanical coupling test. A series of triaxial compression tests with the confining pressures of 5,10,15,20,25,30 MPa are performed on the replica specimens under current natural state and hydrostatic pressures of 1-4 MPa. The result has shown that,the weakening effect is quite significant in the shallow low stress rock mass,the weakening rate of strength parameter f is within 13%,while the weakening effect of c increases dramatically up to 100%with the increasing hydrostatic pressure. The weakening rates of deformation modules increase with the increasing hydrostatic pressure when confining pressure is below 20 MPa,and decrease when confining pressure increases. However,when confining pressure exceeds to 20 MPa, the weakening effect is negligible. A prediction model of rock mass mechanical parameters is established according to the results. These achievements have already been applied to the engineering construction of Jinping I hydropower station,and the research techniques have opened up a new laboratorial way for research on rock mass mechanical properties.