Long term stability of cut slope and determination of effective strength index of soils

Abstract

This paper is concerned with the long term stability problem of cut slope. To investigate the decrease of strength and the change of strength index of submerged soils, a series of triaxial shear tests were carried out on both submerged and non submerged cohesive soil specimens.Some laboratory simulation tests were also conducted to illustrate the change of stress path of soil in cut slope induced by rainfall and variation of groundwater level. From above tests, we can obtain that the effective cohesion parameter is almost equal to zero and the angle of shearing resistance is near to that of normally consolidated soils under submerging and the long term geological weathering. The validity of the method of strength indexes determination was confirmed by a practical failure case with total stress method and effective stress method . Based on the experimental results, a simplified, practical and economic method of the determination of strength indexes is proposed. 对人工开挖边坡的长期稳定性问题进行了一系列的室内三轴剪切试验 ,探讨了黏性土在浸水后的强度降低程度 ,以及强度指标的变化情况 ,模拟了降雨和地下水位变动时土中的应力状态变化过程 ,得出了人工切土边坡由于水的浸入、长期地质风化、扰动等因素 ,使有效黏聚力几乎降低为零 ,有效内摩擦角和正常固结状态的接近 ,并通过工程实例用有效应力法和总应力法对边坡稳定性进行了分析验证 ,为人工切土边坡的长期稳定性计算和强度参数确定提供简便、实用和经济的方法。