边坡稳定性分析的物质点强度折减法

采用更新拉格朗日控制方程的物质点法模拟边坡失效过程。基于广义插值物质点法以及弹塑性土体模型,提出了物质点强度折减法,并用于边坡稳定性分析,具体步骤为:划分背景网格,确定物质点;分步加载重力以消除物质点的应力振荡,确定边坡初始应力场;折减强度参数,计算边坡塑性区分布及土体变形,确定安全系数。算例表明,物质点强度折减法与有限元强度折减法计算结果相近。同时,物质点强度折减法可采用坡顶点竖直方向的位移是否突变作为边坡失稳判据。此外,利用物质点强度折减法还发现,在某一折减系数下,即使塑性区贯通,边坡仍然具有一定的稳定性,不会立即发生位移突变,为边坡稳定性分析提供了新的思路。

Strength reduction material point method for slope stability

The material point method, employing updated Lagrangian formulation, can be used to simulate the failure process of slopes. The strength reduction material point method is proposed to analyze slope stability, based on the generalized interpolation material point method and the elastoplastic constitutive model. The detailed procedure is as follows. Firstly, the grid is divided and all the material points are identified. Then, an incremental gravitation model is employed to eliminate the stress oscillation and to determine the initial stress field of slope. Finally, the parameters of the soil strength are reduced, and the safety factor is determined according to the distribution of the plastic zone as well as the deformation of the soil. The illustration shows the results of the strength reduction material point method are almost identical with those of strength reduction finite element method. Meanwhile, the slope failure criterion of the strength reduction material point method may use the fact whether a sudden displacement change occurs along the vertical direction of the slope crest. Also, using strength reduction material point method, it is discovered that even the plastic zone breaks through under a certain reduction coefficient, the slope still remains stable, and no sudden displacement change will occur immediately. The proposed method offers a new idea for the analysis of slope stability.