SPH方法与经典边坡稳定分析方法的对比研究

Comparative study on SPH method and traditional slope stability analysis method

基于不同的理论基础或引入不同的条间力假定,当前岩土工程中主要发展了三种边坡稳定分析方法,即极限平衡法、强度折减法、极限分析上限法。为了探讨三种方法对不同边坡稳定问题的适用性,采用三个典型边坡算例,对三种传统边坡稳定分析方法所得安全系数和临界滑动面(滑动区域)与光滑粒子流体动力学方法(Smoothed Particle Hydrodynamics,SPH)计算云图进行了对比,结果显示:对于简单的均质边坡,三种方法所得安全系数和滑动面基本一致;对于无黏性土边坡,极限分析上限法结合不连续布局优化方法(Discontinuity Layout Optimization,DLO)应用时会出现不易收敛,甚至计算失败的现象;对于多层且包含软弱土层的边坡问题,极限平衡法和强度折减法计算所得安全系数基本一致,极限分析上限法所得安全系数偏高;极限分析上限法和SPH方法所得临界滑动面基本一致。因此,对于边坡稳定问题的求解,建议采用多种方法进行综合比较。

Three major slope stability methods have been developed in geotechnical engineering based on different theoretical basis or assumptions on interslice force function,namely limit equilibrium method,strength reduction method and upper bound limit analysis method.In order to investigate the applicability of the three traditional methods to different slope stability problems,three typical slope examples are used to compare the safety coefficient and critical failure surface(sliding area)obtained by three traditional methods and those calculated by smoothed particle hydrodynamics(SPH).The comparative study shows the following results.(1)The safety coefficient and the location of critical failure surface obtained by three traditional methods agree well with each other for homogeneous slopes;(2)The upper bound limit analysis method combined with discontinuity layout optimization(DLO)method may fail to provide a rational result for the cohesionless soil slope;(3)For the multi-layer slope with soft soil layer,the limit equilibrium method and strength reduction method provide almost identical safety coefficient,while the upper bound limit analysis method tends to give a larger safety coefficient.The critical failure surface obtained by upper bound limit analysis method agrees well with that demonstrated by SPH.Therefore,a variety of methods are recommended to be used to solve the slope stability problems.