基于Morgenstern-Price法和强度折减法的边坡稳定性对比分析

Comparative Analysis on Slope Stability Based on Morgenstern-Price Method and Strength Reduction Method

应用Morgenstern-Price法和强度折减法,对云南省宣威市万家口子水电站附近的九子崩塌堆积体的主滑体进行稳定性分析,考虑了正常蓄水位、库水位下降和地震作用时的正常蓄水位、库水位下降4种工程情况。结果表明:Morgenstern-Price法所得稳定系数随着蓄水位的下降而减小,在考虑地震作用的情况下,稳定系数也相应降低;强度折减法所得数据则不一样,蓄水位不同时,稳定系数则变化不大。相同蓄水位情况下,考虑地震时稳定系数有所减小,强度折减理论对于简单的均质土坡可能会得到与极限平衡法接近的稳定系数和滑动面,但对于非均质(如成层)土坡,则会有较大的差异性。Morgenstern-Price法使用条分法对滑动岩土体进行受力分析,针对的是人为假定的土体极限平衡条件,不能提供边坡的位移信息,需在计算中事先假定出若干个滑动面;强度折减法通过降低材料的强度参数来达到极限平衡状态,能够考虑土体的应力-应变关系,同时能给出边坡的位移信息,但是缺乏统一的边坡达到极限破坏的判断标准。2种方法都可为边坡稳定性提供有效的分析与评价。

The stability of the primary accumulations which is called Jiuzi collapse accumulation near Wanjiakouzi hydropower station in Xuanwei City,Yunnan Province wss analyzed by using Morgenstern-Price method and strength reduction method,taking into account four conditions such as the normal water level,the dropped level,and the two levels when earthquake occurred.The stability coefficient obtained by Morgenstern-Price method decreased with the storage level not only in the normal condition but also in the case of earthquake condition.But there is little change in the stability coefficient obtained by strength reduction method when water level varied.At the same water level,smaller stability coefficient could be achieved in earthquake condition.As to simple homogeneous soil slope,similar stability coefficient and slide surface may be achieved through strength reduction method and limit equilibrium method.And greater difference may occur when the slope is inhomogeneous.Morgenstern-Price method,assuming soil in the limit equilibrium,uses slices method in forces analysis,and it can not provide the slope displacement information,and several sliding surfaces should be assigned before calculation.In strength reduction method,the limit equilibrium state can be reached by reducing the strength parameters of the materials,and not only the soil stress-strain relations can be considered,but also the slope displacement information can be obtained.However,the strength reduction method is lack of a unified standard when slope reaches to the limit failure.Both methods can provide effective analysis and evaluation for slope stability.