基于渐进微震损伤效应的蓄水期库岸稳定性分析

Stability analysis of reservoir bank slope during reservoir impoundment based on effect of progressive microseismic damage

大岗山水电站自2014年12月开始蓄水,至2015年11月库区水位从975 m升至1 130 m。水电站右岸边坡地质条件复杂,发育有辉绿岩脉、卸荷裂隙带和断层等不良地质体,降低了岩体性状,使右岸边坡在蓄水期存在局部或整体失稳的风险。通过对右岸边坡实施微震监测,获得了蓄水过程中右岸边坡微破裂的演化规律。结合微震监测信息,应用三维岩石真实破裂过程分析方法(RFPA3D-Centrifuge)计算蓄水期右岸边坡在渐进性微震损伤效应下安全系数随库水位升高的变化过程。经计算,边坡安全系数随库水位升高而降低,库水位升高对边坡稳定性有不利影响。最终安全系数为1.76,满足规范要求,说明蓄水过程中边坡处于稳定状态。

The Dagangshan Hydropower Station began to impound in December 2014, and the water level increased from 975 m to 1130 m in November 2015. The right bank slope was subjected to complex geological condition, including diabase dikes, unloading fissures and fractures, which attributed to the local or overall failure of right bank slope in the process of water impoundment. The evolution of micro-fractures of the right bank slope during impoundment was obtained by microseismic monitoring technique. Combining the abundant microseismic monitoring information, the safety factor of the right bank slope during impoundment was calculated by realistic failure process analysis code in three dimensions(RFPA3 D). Through considering the effect of progressive microseismic damage, the results showed that the safety factor decreased as the water level increased. The final safety factor was 1.76, which met the requirement of the specification, indicating that the right bank slope was overall stable in the process of water storage.