顺层岩质路堑边坡稳定性数值极限分析

Numerical limit analysis of stability for bedding rock cutting slope

针对顺层岩质路堑边坡稳定的关键影响因素,采用有限元强度折减法,研究了边坡高度、坡顶堆载及工程防护对具一组贯通软弱结构面的顺层岩质边坡模型稳定性的影响,并与传统极限平衡法进行了对比验证。研究结果表明:边坡坡度大于岩层倾角时对稳定不利,安全系数随边坡高度增加而降低;坡顶堆载时,安全系数的降低取决于荷载和贯通塑性区的相对位置;挡土墙或锚杆通过对塑性区贯通带的阻截使塑性区转移到其他更薄弱的结构面,从而提高安全系数,塑性区贯通带的转移去向取决于初始支撑强度;基于Drucker-Prager屈服准则的安全系数有限元计算结果比基于莫尔-库仑准则的传统极限平衡法计算结果平均高出约22%,与郑颖人等约为25%的研究成果非常接近,说明有限元强度折减法可行。

According to the key influencing factors of bedding rock cutting slope stability,the influences of slope height,load on the top of slope and engineering protection on the stability of bedding rock slope model with a group of the runned-through planes of weakness were studied by nonlinear FEM srength reduction method,and traditional limit equilibrium method was used for comparison and verification.Analysis result shows that when the slope grade is larger than rock obliquity,it is disadvantageous to slope stability,and safety coefficient decreases with the increase of slope height.When load is applied on the top of slope,the reduction of safety coefficient depends on the relative position between load and runned-through plastic zone.Retaining wall or anchor rod can increase slope safety coefficient by blocking and intercepting runned-through plastic zone,and plastic zone moves to other more weak structural plane,its moving direction depends on initial sustaining strength.The finite element calculation result of safety coefficient based on Drucker-Prager yield criterion is about 22% higher than the result of traditional limit equilibrium method based on Mohr-Coulomb criterion,it is very close to the research result of about 25% by Zheng Ying-ren,et al,so finite element srength reduction method is feasible.5 tabs,14 figs,15 refs.