非稳定渗流条件下非饱和土质边坡稳定性的矢量和分析法研究

A vector sum method for stability analysis unsaturated soil slope subjected to transient seepage

研究可以同时考虑渗流、变形与稳定的非饱和土质边坡稳定性分析方法具有重要的理论意义及工程实用价值。基于Fredlund双应力变量理论进行非饱和非稳定渗流-应力耦合分析,同时与传统非耦合渗流方法确定的孔压场进行对比发现,两种方法确定的浸润线变化过程相近,堤底处孔压的最大相对误差为8.8%,验证了耦合分析结果的可靠性。将基质吸力对强度的贡献纳入黏聚力中得到坡体强度参数的空间分布规律,又基于滑面强度参数时空分布规律借助Matlab平台开发了非稳定渗流条件下非饱和土质边坡稳定性的矢量和法分析程序。以库水位下降条件下堤坡的稳定性分析为例,将不同方法的计算结果进行对比,发现文中方法搜索得到的滑面位置相对于传统方法要深缓,但总体位置相差不大,不同方法对应的安全系数相差不足0.096,验证了所提方法的合理性。

It has significant theoretical and practical meaning to propose a method of unsaturated soil slope stability analysis accounting for seepage, deformation and stability simultaneously. Firstly, coupled analysis of transient unsaturated seepage-stress is achieved using the double-stress variables theory of Fredlund. Comparative analysis with pore pressure field is done by the traditional uncoupled method. Variation process of phreatic lines are close to each other, and the maximum relative error of pore pressure is 8.8% at the bottom of embankment; thus the reliability of coupled analysis results are verified. Secondly, it is possible to consider the matric suction term as a part of the cohesion of the soil, and the spatial distribution law of strength parameters of the slope is obtained. Analyzing program of vector sum method of unsaturated soil slope stability analysis subjected to transient seepage based on Matlab has been developed. Finally, taking the influence of drawdown of reservoir water level on slopes stability of embankment for example, comparative analysis between traditional method and proposed method indicates that potential slip surfaces are similar and the difference of safety factors are less than 0.096; thus the rationality of the method proposed in this paper is verified.