地震作用下边坡岩体动力稳定性数值模拟

NUMERICAL SIMULATION OF DYNAMIC STABILITY OF SLOPE ROCK MASS UNDER SEISMIC LOADING

以金沙江龙蟠边坡变形岩体为例,采用人工合成地震动为输入条件,并考虑超静孔隙水压力的作用,运用离散单元法进行边坡岩体的全时程动力分析,探讨地震作用下边坡岩体的动力响应规律及稳定性。数值模拟结果表明:地震惯性力的作用引起剪应力的积聚效应;岩体结构面对岩质边坡的地震动力响应起控制性作用;边坡最危险状态是地震刚刚开始时由静态到动态所发生的巨大系统改变之时;地震作用导致岩体变形破坏的主要机制是剪应力积聚和超静孔隙水压力累积效应的耦合作用。同时,计算结果还表明,龙蟠边坡变形岩体在遭受地震时不会发生整体性的远程滑动,这一结论对金沙江宽谷坝址的抉择具有重要的工程应用价值。

Taking the deformed rock mass of Longpan slope along Jinsha River for example,the dynamic response and failure mechanism of slope rock mass under seismic loading are simulated by distinct element method.The time-history curve of artificially synthetic acceleration is used,and the effect of excess static pore water pressure is taken into account.The following results are obtained.The seismic inertia force results in accumulation of shear stress.The discontinuous structures are crucial to wave transmission.The ultimate dynamic response of slope system takes place at the initial period of seismic loading.Essentially the main mechanism of deformation and failure of rock mass induced by earthquake is the coupling effect of shear stress and excess static pore water pressure accumulation.At the same time,the results show that the deformed rock mass of Longpan slope is unlikely to form a long-distance landslide.This conclusion has important application value for the choice of dale dam site along Jinsha River.