基于变形分析的3维边坡滑动面搜索新方法

A New Method for Searching Critical Slip Surface of Three-dimensional Slope Based on Deformation Analysis

针对3维强度折减法定量化确定滑动面的不足,提出了一种新的3维边坡滑动面搜索方法。边坡岩土体变形只有超过临界值后,才能产生滑裂破坏。因此可以根据3维强度折减法所得的位移场,采用临界位移等值面(即3维滑体与稳定体的分界面)定义临界滑动面。根据特定剖面边界的剪应变增量极大值点确定滑体剪出口位置,据此求解对应的临界位移值。采用自编的FISH程序将临界位移节点3维坐标和对应的位移值输出,通过离散节点网格化搜索滑动面。对不同实例进行分析,包括匀质边坡、坡顶荷载作用下的边坡、含软弱夹层的边坡以及凸面边坡等。研究表明,即使是匀质边坡,其滑动面形状都不能简单地假设为球面、椭球面或对数螺旋面。算例分析也进一步说明了3维强度折减法的优势,即不需要引入滑动面形状,更能真实地反映3维边坡破坏机制。

Due to the drawback of three-dimensional strength reduction method for quantitatively determining the critical slip surface, a new method for searching critical slip surface of three-dimensional slope was presented. When the deformation of soil exceeds the critical value, shear failure could be considered to occur. Based on the displacement field obtained by three-dimensional strength reduction method, the critical displacement contour surface （ interface between slip mass and stable mass） was defined as critical slip surface. The position of the shear outlet of slip mass was obtained by maximum point of shear strain increment on the boundary of specific section. Thus, the corresponding critical displacement value could be solved. FISH program was used to get coordinates and corresponding dis- placement value of nodes from displacement contour lines. Then the critical slip surface could be determined by discrete point data grid- ding. Extensive examples which contain homogeneous slope, slope imposed on loading, slope with weak layer and convex slope, were given for demonstrating the validity of the present method. The result showed that the shape of three-dimensional slope is not spherical surface, ellipsoid or logspiral surface, even for homogeneous slope. Furthermore, the application showed that there lies practicability ad- vantage in three-dimensional strength reduction method. The assumption about the location and shape of 3D slip surface isn＇t required which can truly reflect the failure mechanism of three-dimensional slope.