某水电工程边坡开挖及支护过程稳定性分析

为分析水电工程边坡在开挖及支护全过程中稳定性变化情况,评价锚索支护效果,以西南某一水电站开挖边坡为研究对象,通过地质分析和变形监测确定边坡变形模式,对开挖和支护过程中各变形模式采用基于极限平衡理论的Morgenstern-Price法进行了多种工况下的稳定系数计算。结果表明:边坡的6种滑动模式在持久、偶然和短暂工况下的稳定系数均满足规范要求。二期锚索施加完毕后,边坡整体稳定系数大于原始边坡,锚索对边坡的控制作用明显,支护效果良好。边坡在开挖至坡脚之前稳定系数逐渐增大,边坡开挖有利于边坡稳定,坡脚开挖以后,边坡稳定系数骤降,开挖不利于边坡稳定,坡脚岩体对边坡稳定作用明显。研究成果可为水电工程边坡的稳定性分析以及类似工程边坡的开挖及支护设计提供参考。

Stability analysis on slope of a hydropower project during excavation and supporting

In order to analyze the variation of the stability of the slope of hydropower project during the whole process of excavation and supporting，the stability coefficients under several working conditions are calculated with the limit equilibrium theorybased Morgenstern-Price method for all the deformation modes during the excavation and supporting through determining the slope deformation mode with the relevant geological analysis and deformation monitoring by taking the slope excavation for a hydropower station in the Southwest China as the study objective. The result shows that all the stability coefficients of six sliding modes under the persistent，accidental and transient conditions can meet the requirement of the relevant criteria. After the application of the secondary anchorage cable，the stability coefficient of the whole slope is larger than that of the original one and then the control effect of anchorage cable on the slope is obvious，thus the supporting effect is better. The stability coefficient of the slope is gradually increased before the excavation till the slope toe，and thereby，the slope excavation is favorable for the stability of the slope， while the stability coefficient of the slope is suddenly decreased after the excavation of the slope，consequently，the excavation is unfavorable for the slope stability; thus the rock mass at the slope toe has an obvious effect on the slope stability. The study result can provide references for analysis of the slope stability for hydropower project as well as the excavation and supporting of the slope for the similar project.