地震作用下库区堆积层滑坡失稳机制

为研究地震作用下库区堆积层滑坡失稳机制,以雅鹊湾滑坡为例,基于Geo-Studio中Quake/W和Slope/W耦合建立数值模型,分析其在地震作用下的稳定性变化和动力响应.在地震作用下滑坡稳定系数在1.199 ～0.859波动,随着库水位由175 m降低到145m,滑坡稳定性由欠稳定降为不稳定;堆积层越厚的部位,受到地震作用后位移越大,滑带和后缘基岩发生的位移较为一致;监测点峰值加速度随高程的增加而增加,且加速度峰值的出现时间也随高程增加而滞后;坡面峰值加速度受到坡度的影响,监测点坡度发生较大改变时,峰值加速度会相应的减小.分析其在地震作用下的失稳机制,得出堆积层滑坡后缘剪切破坏,表层岩土体沿平行于滑带的滑面滑动,剪出口为库水位淹没的区域,滑坡由表层向深部滑动,最终基岩上覆土体全部滑动破坏,同时滑坡滑移会导致后缘基岩产生临空面,极易发展成为崩塌灾害.

Study on instability mechanism of accumulation layer landslide under earthquake action

This paper studies the mechanism of landslide instability of accumulation layer under reservoir earthquake. Taking Yaquewan landslide as an example, a numerical model was established based on the coupling of Quake/W and Slope/W in Geo-Studio to analyze its stability change and dynamic response under the action of horizontal earthquake. It is concluded that the stability coefficient of the landslide of this accumulation layer fluctuates between 1.199~0.859 with time under the action of horizontal earthquake. As the reservoir water level decreases from 175m to 145m, the stability of the landslide decreases from unstable to unstable. The thicker the accumulation layer is, the larger the displacement is after the earthquake, and the displacement of the sliding zone and the bedrock at the back edge is consistent. The peak acceleration of monitoring point increases with the increase of elevation, and the time of peak acceleration also lags with the increase of elevation. The peak acceleration of the slope is affected by the slope. When the slope of the monitoring point changes greatly, the peak acceleration will decrease accordingly. Analysis of the instability mechanism of under horizontal seismic action, it is concluded that shear damage accumulation landslide trailing edge, the surface rock mass along the parallel to the sliding surface sliding of the sliding zone, cut exports for water flooded area, landslide from the surface to the deep sliding, eventually overlaying soil sliding damage, landslide slip at the same time can lead to trailing edge bedrock airport surface, easy to become a collapse.