凹型边坡稳定性分析中的侧面力取值方法探讨

Method for lateral forces in stability analysis of concave slopes in plan view

尽管凹型边坡的稳定性高于直线边坡是众所周知的,要准确计算凹型边坡的安全系数却很难,因为垂直于滑动方向侧面力对稳定性有影响,但是目前还没有合适方法计算其的大小。出于简化考虑,现有研究多按主动土压力计算该侧向力。为了检验按主动土压力计算该力的合理性,将侧面力分别按主动、静止和被动土压力取值,基于Spencer法概念推导了考虑侧压力的凹型边坡稳定性计算方法,然后用Matlab软件编制了计算程序,分析了三种土压力取值方法下,凹型边坡稳定性安全系数的差异。结果表明,将侧向压力考虑为土压力或静止土压力,凹型边坡的稳定性甚至低于相同条件直线边坡;而将侧向压力考虑为被动土压力,凹型边坡的安全系数结果又显著大于有限差分软件Flac3D分析结果,因此,将凹型边坡的侧压力简单按土压力取为主动、静止和被动土压力都是不合理的,如何计算凹型边坡的侧面力,还需要进一步深入研究。

Although it is well known that the stability of concave slopes in plan view is better than that of straight slopes, it is difficult to accurately calculate the factor of safety of concave slopes because the lateral forces perpendicular to the sliding direction have an effect on the stability, but there is no suitable method to calculate them. For the sake of simplification, the existing studies calculate the lateral forces by treating that they are active earth pressures. In order to verify the rationality of that treatment, the lateral forces are regarded as the values of active, static and passive earth pressures respectively. Based on the Spencer method, the method for calculating the stability of a concave slope is deduced considering the lateral forces. And then the calculation program is compiled by using the Matlab software to analyze the difference of factor of safety of the concave slope under three different soil pressures. The results show that by considering the lateral pressure as the earth pressure or the static earth pressure, the stability of the concave slope is even lower than that of the straight slope. When the lateral pressure is considered as the passive earth pressure, the factor of safety is significantly larger than that calculated by the finite difference software Flac3 D. Therefore, it is unreasonable to simply regard the lateral pressure of the concave slope as the earth pressure as the active, static and passive earth pressures. How to calculate the lateral forces of the concave slope is still a problem to be further studied.