基于点稳定系数法的斜坡稳定性分析

基于莫尔-库伦强度理论构架,界定了点稳定系数的概念,并推导其计算公式。利用Geostudio软件建立了均质斜坡模型及计算其应力分布,并在此基础上结合MATLAB软件计算斜坡模型中各点的点稳定系数,勾绘出斜坡体内不同稳定度区域,探析了斜坡稳定性,并与传统极限平衡法进行了对比。对比结果表明:对直立斜坡,两种方法的计算结果均为不稳定,但点稳定性系数法勾绘出坡脚及坡脚底部存在两处不稳定区域;对60°斜坡,点稳定系数法的计算结果表明坡脚处存在潜在不稳定区域,而极限平衡法的计算结果表明坡体处于稳定状态;对45°斜坡,两种方法的计算结果均为稳定,计算结果一致。进一步分析得到结论:点稳定系数法不需要假设或指定某一形状滑面进行斜坡稳定性评价,且可考虑应力集中对坡体稳定性的影响;极限平衡法以稳定系数表达计算结果,而点稳定系数法以不稳定区域表达计算结果。在分析了应力和岩土体力学参数因素对点稳定系数法计算结果的敏感性后发现:相对于极限平衡法,岩土体力学参数对点稳定系数法影响更为敏感,存在黏聚力界限点和内摩擦角界限点,且对均质斜坡破坏形式(局部滑动变形破坏或整体压缩变形破坏)起着非常重要的作用。

Analysis on Slope Stability Based on Local Factor of Safety

The local factor of safety (LFS)formula was derived based on the Mohr-Coulomb strength theory and the concept of LFS was redefined.The stress distribution of the slope was calculated by using Geostudio software,combined with MATLAB for the calculation of LFS for each point in the slope model to outline the stable and unstable regions for analysis of the slope stability.Comparison of the results by the local factor of safety method(LFSM)and the limit equilibrium method (LEM)shows that for a vertical slope,both LFSM and LEM predict that it is unstable,whereas the LFS delineated a zone of potential failure behind the vertical face and near the toe.For a 60°slope,the LEM predicts that the factor of safety is greater than 1.00,whereas the LFSM delineates a zone of potential failure near the toe.For a 45°slope,both LFSM and LEM predict its stability.Further analysis shows that LFSM can analyze the slope stability without needing to identify or assume any potential failure surfaces,the stress concentration problem can be taken into consideration for slope stability analysis.The LFSM displays the results by unstable regions,while LEM shows the factor of safety.Sensitivity analysis of stress and geotechnical parameters in LFSM and LEM were conducted and the results revealed that in comparison to LEM,LFSM is more sensitive to the variation of geotechnical parameters.There exist boundary points of cohesion and internal friction angle that play important roles in determining the failure shape (partial deformation or damage,whole compression deformation or damage)of slope.