土石混合边坡块石随机生成方法与稳定性分析

Method for Generating Random Soil-rock Mixed Slope and Stability Analysis

针对传统边坡稳定性分析方法未考虑土石混合体边坡内部块石的不足,采用MATLAB编制相应程序生成一定级配随机块石数据,再通过AutoCAD将数据文件转化为图形交互文件,导入Midas建立对应的块石边坡网格模型.最后,通过Midas_to_Flac3d接口程序,生成Flac3d模型,用Flac3d内嵌的有限差分强度折减法对块石边坡进行稳定性分析,并探讨土石界面强度等关键参数对土石混合边坡稳定性的影响.计算结果表明,忽略块石的存在将会给边坡稳定性计算结果引起较大的差异,坡体内塑性区并不像均质土坡那样为规则的类圆弧形态,而是在多种塑性区扩展路径的综合作用下呈现出多滑动带现象,滑动带在贯通过程中有明显的绕石效应,滑动带长度较等效均质土坡有明显延长;在所选定接触面参数变化范围内,接触面刚度参数(法向刚度、切向刚度)对边坡安全系数影响较小,而接触面强度参数(摩擦角、粘聚力)对边坡安全系数影响显著.

During the traditional slope stability analysis, soil-rock mixed slope is always regarded as homogeneous soil slope,and rock blocks are neglected.In this paper,a piece of MATLAB code was devel- oped to generate random rock data containing multiple group particle sizes.By using AutoCAD, the genera- ted rock data was conversed to interactive graphics files, which can be imported into Midas for model mes- hing.Then, the Flac3d model was generated through a Midas to Flac3d interface program,and was used to analyze the stability of the soil-rock mixed slope by the method of strength reduction finite difference, which was embedded in Flac3d strength reduction finite difference.With the developed Flac3d model, the influence of some key parameters including the soil and rock interface strength on the stability of the soil- rock mixed slope was analyzed.The results show that neglecting rock blocks may lead to large difference in slope stability evaluation. The plastic zone in the heterogeneous slope is not a similar circular arc as the homogeneous slope, but under the combined effect of a variety of plastic zone propagation routes, it shows a multi-sliding phenomenon.Meanwhile, there is an obvious rounding rock effect through the process, and the sliding length compared with the equivalent homogeneous soil slope has a significant extension.Within the selected scope of the interface parameter changes, the stiffness parameters （normal stiffness and shear stiffness） have little effect on the factor of safety, but strength parameters （friction angle and cohesion） have significant influence on the slope stability.