考虑填料与土地基差异性的填方边坡稳定性上限分析

Upper bound limit method for stability analysis of fill slope considering difference between filling and foundation soil

考虑到填方边坡中填方部分填料与地基土体力学特性存在差异性,表现出明显的"两层土结构"特征,基于上限法推导适用于填方边坡稳定性计算式,并通过与已有的研究成果进行对比分析。同时,分析土体黏聚力比、内摩擦角以及边坡坡度对填方边坡稳定性及其滑动面参数的影响。研究结果表明:本文计算式所得稳定性系数Ncr更小,验证了所推导的即计算式的可靠性;随着黏聚力比增大,滑动面出口角度β′、临界高度Hcr与比黏聚力比为1时的临界高度Hcr0之比(即Hcr/Hcr0)均呈非线性增大,β′最后稳定在边坡坡度;内摩擦角、边坡坡角对Hcr/Hcr0的影响与黏聚力比有关,即地基土与填方填料的差异性明显影响填方边坡稳定性及其滑动面形状;地基土强度提高可使地基所需加固深度降低。研究成果可为填方边坡填料选取、地基加固设计提供参考。

With consideration of the difference between the mechanical properties of the filling and foundation soil in the fill slope,and the obvious characteristic of"two-layer soil structure",a calculation formula for the stability of the fill slope was derived based on the upper limit method.The effects of soil cohesive ratio,internal friction angle and slope gradient on the slope stability and its sliding surface parameters were analyzed.The results show that the stability coefficient Ncrcalculated by the formula is smaller,which verifies the reliability of the derived calculated formula.The angleβ′at the exit of the sliding surface and the ratio of critical height Hcrto critical height Hcr0 with cohesion ratio of 1(i.e.Hcr/Hcr0)increase nonlinearly with the increase of cohesion ratio,andβ′finally approaches the slope value.The influences of internal friction angle and slope angle on Hcr/Hcr0 are related to the cohesion ratio,which indicates that the difference of mechanical properties between foundation soil and filling can obviously affect the stability of the filling slope and the shape of the sliding surface.The increased strength of the foundation soil can reduce the required depth of the foundation reinforcement.The research results can provide reference for the selection of filling material and the design of foundation reinforcement of fill slope.