基于最大剪应变增量的边坡潜在滑动面搜索

A method for searching potential failure surface of slope based on maximum shear strain increment

滑动面位置和形状的判断是影响边坡地基稳定性分析合理性的主要因素,合理地确定滑动面的位置和形状是边坡地基稳定性分析首先要解决的问题。由岩土工程常用的Mohr-Coulomb度理论可知,岩土体破坏是由于某一面上的剪应力达到了岩土体的剪切强度,此时剪切面上必然发生较大的剪切变形,因此可以通过搜索最大剪应变增量的位置来确定边坡滑动面。基于以上思路,综合运用有限差分软件FLAC3D和曲线拟合技术,提出基于最大剪应变增量确定边坡地基潜在滑动面的方法。首先,利用有限差分软件FLAC3D计算极限状态时边坡内的应力、应变,在计算剖面中设置一系列的垂线,利用FISH语言编制程序搜索垂线上剪应变增量最大位置的坐标,以获得滑动面上的离散点坐标。然后,通过最小二乘的方法对离散点进行曲线拟合,得到滑动面的形状和位置。通过与极限平衡法的对比分析,验证文中方法的合理性。文中方法的判断标准物理意义明确,简便实用,且克服了对网格的依赖性。

A main factor affecting the rationality of the sloped foundation stability analysis is to determine the position and shape of the sliding surface。Therefore the first problem of the sloped foundation stability analysis to be solved is to reasonably determining the position and shape of the sliding surface.The Mohr-Coulomb yield criterion,commonly used in the geotechnical engineering,shows that the failure of the rock and soil mass is due to the reach of the shear stress on someone surface to its shear strength,when there must occur a large shear deformation on the shear plane.Therefore,the sliding surface can be determined through searching the positions where have the largest shear strain increment.Based on the ideas above,comprehensively using the finite difference software-FALC3Dand the curve fitting technique,the paper proposes a method,based on the largest shear strain increment,to determine the potential sliding surface.Its specific processes steps are that: firstly,the stress and strain in the slope are calculated by using the finite difference software-FALC3D;then a series of vertical line would be set in the calculating section,and then the discrete coordinates of the sliding surface,where the shear strain is largest on the vertical line,would be found through programming FISH program.Then the position and shape of the sliding surface can be obtained through carrying out the curve fitting of the discrete points by using the least squares method.The rationality of the proposed method is verified through comparatively analysing the limit equilibrium method.The method has a criterion with clear physical significance and is simple,convinient and practical for application and also overcomes the dependence of the calculting grid.