映秀湾水电站大型地下洞室群三维非线性损伤地震响应数值分析

3D numerical analysis on nonlinear damage seismic response of large underground caverns of Yingxiuwan hydropower station

基于深埋大型地下洞室群围岩损伤机理,对映秀湾水电站洞室群在三向地震荷载耦合作用下的动力响应进行了三维非线性数值模拟,分析了在有、无支护条件下洞室周边围岩关键部位的加速度、位移及应力的时程变化及分布规律,得出了地震荷载作用下围岩损伤分布特征。计算结果表明,在地震荷载作用下,除了因尾水洞体型及断层影响厂房底板及尾水洞交口处受力状态较差外,在锚固条件下整个洞室的围岩损伤、洞周位移、应力分布和锚杆受力都较为合理,说明支扩系统基本保证了洞室的抗震稳定性,但上、下游边墙及吊车梁相对位移达到了10cm左右,导致吊车无法正常运行。

A 3D nonlinear dynamic model is adopted to analyze the time-history and space distribution of acceleration, displacement, stress field and damage zones at the key positions of large underground caverns. This model is based on the damage mechanism of surrounding rocks under the coupled earthquake loads in three directions. The simulation results for the two cases with and without an anchorage support show that under the earthquake loads the conditions of rock damage, displacement, stress field and cable stress of the surrounding rocks with an anchorage support system are fairly good, except for the stress conditions at the bottom of the main cavern and at the intersect with the tail-water cavern where the effect of geological faults is considerable. This suggests that an overall aseismatie stability of caverns can be achieved with an anchorage support system, but there remains a relative displacement of 10cm between the up and down sidewalls, which may cause a difficulty for the crane to run normally.