非饱和土质边坡安全稳定影响因素研究

A Study on the Factors Affecting the Safety Stabilityfor the Unsaturated Soil Slope

传统边坡设计通常忽略非饱和土的水力与力学特性对边坡稳定性的影响,非饱和土边坡稳定性分析需要采用非饱和土力学相关理论。部分学者通过对比二维和三维边坡稳定分析结果,发现这两种分析方法所得的安全系数差异大致在10%以内。以典型非饱和土质边坡的稳定性为背景,基于极限平衡分析法考虑非饱和土抗剪强度和非饱和土重度,对土的物理性质、边坡坡高和边坡坡角等影响因素进行分析。研究发现,非饱和土的力学性能、水力性能以及重度都会随着含水率的变化而变化。采用变化重度和恒定重度开展边坡稳定性分析,所得到的边坡稳定安全系数差异明显。结果表明,采用变重度的分析方法与传统恒定重度的分析方法所得安全系数的差异随坡角增加而增大,最大值达20%左右,明显高于二维和三维分析方法的差异。如果考虑非饱和土力学性能对非饱和土质边坡稳定性的影响,变重度和恒定重度分析方法所得安全系数差异得以进一步放大。

Both hydraulic and mechanical properties of unsaturated soil are ignored in the conventional design of the constructed slope.The principles of unsaturated soil mechanics should be adopted in the stability analysis for unsaturated soil slope.Researchers have conducted comparison for the 2D and 3D analysis and observed the difference between the obtained factors of safety is within 10%.Taking the slope stability for the typical unsaturated soil slope in the project as the background,based on the limit equilibrium analysis method,GeoStudio software is used to consider the shear strength and the weight of unsaturated soil,and the physical properties of soil,slope height and slope angle are analyzed.It is found that the hydraulic conductivity,shear strength and unit weight of unsaturated soil vary with the changes in the water contents.Slope stability analysis considering the actual unit weight(varying unit weight)and the constant unit weight.The results show that the difference in the obtained FoS from above two methods increases with increase in slope angle,the maximum difference is around 20%which is higher than the difference for the 2D and 3D analysis.In addition,if the unsaturated shear strength is considered in slope stability analysis,the difference in FoS from two methods can be amplified.