锦屏I级水电站左岸坝肩边坡施工期破坏模式及稳定性分析

 由于具有复杂的地质结构，岩石高边坡的变形破坏机制和失稳模式非常复杂。首先采用底摩擦试验研究锦屏I级水电站左岸工程边坡在工程开挖过程中的变形破坏模式。试验结果表明：(1) 变形破坏模式为滑移–拉裂式；(2) 岩体被煌斑岩脉X和f42–9断层共同切割形成不稳定块体，并发生失稳破坏。在此基础上，充分利用FLAC3D软件模拟边坡开挖变形的强大功能，分析边坡在开挖过程中可能的变形失稳模式。数值结果显示，f5，f8，f42–9断层以及裂隙密集带SL44–1和煌斑岩脉X等软弱结构面控制岩体的开裂和边坡的失稳。然后，通过有限元强度折减法计算得到工程边坡在不同工况下的安全系数：天然状态下边坡安全系数为1.277；开挖工况下边坡安全系数为1.152；施加支护措施后边坡安全系数为1.385。

FAILURE MODE AND STABILITY ANALYSIS OF LEFT BANK ABUTMENT HIGH SLOPE AT JINPING I HYDROPOWER STATION

Because of complex geological structure，the deformation failure mechanism and instability mode of high rock slope are usually very complicated. The deformation and failure mode are analyzed by the base friction experiment during the excavation of left bank slope at Jinping I Hydropower Station. The experimental results show that：(1) the failure mode is sliding and fracturing；and (2) rock masses are cut into instable blocks by lamprophyre veins X and fault f42–9，and then fail. Based on above-mentioned results，a numerical model of the high rock slope in left bank is built with FLAC3D；and the joints and faults are modeled with low-strength material. The results of numerical simulation in the excavation process show that the controlling factors for rock cracking and slope failure can be observed for the faults f5，f8，f42–9，SL44–1 and lamprophyre veins X. Then，factors of safety are calculated through the strength reduction method with numerical model of the high rock slope. Under natural state，the factor of safety of rock slope is 1.277；after excavation，the factor of safety equals 1.152；and the factor of safety will be 1.385 after anchorage cables being applied. The study shows that the potential instable zones of the slope by physical and numerical simulation methods are consistent；and the results are acceptable.