地震作用下砂砾石高边坡稳定性三维分析

Three-dimensional Analysis of Sand-Gravel High Slope Stability under Earthquake Action

大石门水利枢纽工程左岸高边坡砂卵砾石层覆盖厚度为134 m,运行期砂卵砾石遇水软化,饱和强度仅为13~16 MPa。在常年受水体浸泡且遭遇高烈度地震的情况下,保证百米级砂卵砾石层边坡稳定是设计中的难题。针对砂砾石遇水软化边坡失稳定的问题,在保证边坡稳定的前提下,边坡设计采取以开挖为主的"强开挖、弱支护"设计原则,即用缓于砂砾石稳定边坡坡比开挖,确保边坡在地震工况下不会整体失稳。采用有限元动力分析方法,对地震作用下砂卵砾石高边坡的稳定性进行分析。结果表明,地震作用下的位移响应、速度响应、加速度响应程度随着坡高的增加逐渐加大;边坡最危险滑动面发生在坡面靠近第一级马道以下位置,且属于表层滑动;当地震加速度峰值达到0.26 g后,安全系数降低到1.084。

The thickness of sand gravel stratum on the left bank is 134m of Da Shimen hydraulic project, the sand gravel stratum is softened by water in the running time, The saturation intensity is only 13 - 16MPa, It is a difficult problem to ensure the stability of the slope of the 100 - meter sand gravel layer in the case of water immersion and high intensity earthquakes. In order to ensure the stability of slope stability, slope design adopts the principle of ＂strong excavation and weak support＂, which is mainly based on excavation, the slope of the slope is more stable than the excava- tion ensure that the slope is not unstable in the earthquake affairs. The stability of sand - gravel high slope is analyzed by finite element dynamic analysis. The results show that the displacement response, velocity response and acceleration response under earthquake action gradually increase with the increase of slope height; the most dangerous sliding surface in the slope near the first level road following position, and belongs to the sliding surface ; when the peak value of earthquake accel- eration reaches 0.26g, the safety factor is reduced to 1. 084.