利用变模量强度折减法计算结果确定土质边坡临界滑动面的方法  

Searching for critical slip surface in soil slopes based on calculated results by variable modulus elastoplastic strength reduction method

作　　者：张玉成[1,2,3] 杨光华[1,2,3] 胡海英 刘鹏[5] 钟志辉[5] 

机构地区：[1]广东省水利水电科学研究院,广东广州510610 [2]广东省岩土工程技术研究中心,广东广州510610 [3]广东省突发公共事件应急技术研究中心,广东广州510610 [4]华南理工大学土木与交通学院,广东广州510641 [5]武汉大学土木建筑工程学院,湖北武汉430072

出　　处：《岩土工程学报》2013年第S1期14-22,共9页Chinese Journal of Geotechnical Engineering

摘　　要：现有强度折减法用于边坡分析时,通常仅折减强度参数,不折减变形参数,采用的是理想弹塑性模型,其计算的安全系数与传统的极限平衡方法基本一致,获得的主要是边坡的安全系数,但其计算时未能真实考虑土体的非线性,很难得出接近实际的变形场。基于变模量弹塑性强度折减法可获得更符合实际的变形场,针对目前滑动面搜索方法存在的不足,在分析边坡的变形场和应力特点,滑动面的形成机理及其特征的基础上,研究了如何直接通过边坡变形场和应力场确定滑动面,探讨了3种确定滑动面的方法,一种是用位移梯度来确定最不利滑动面的方法;第二种是利用Flac计算方法的特点,利用非滑动区的节点速度趋于零,而滑动区节点速度非常大的特性确定滑动面;最后一种是利用边坡监测中的"测斜管"思想,用跟踪数值分析中节点位移,用发生位移突变的点作为滑动面上的点,拟合各点所得的曲线即为临界滑动面。文章对含软弱夹层黏土边坡的滑动面进行了分析,3种方法得到的滑动面位置比较一致,与传统极限平衡法相比,3种方法不仅可以应用于均质边坡,而且可以用来确定非均质边坡的滑动面。The current strength reduction methods for in slope analysis generally only reduce strength parameters and do nto reduce deformation parameters.Using the ideal elasto-plastic model,the calculated safety factor is almost the same as that by the traditional limit equilibrium methods.Those methods only give the safety factor of slopes.However,they cannot reflect the nonlinear properties of soil,so they cannot give real deformation field.Based on the variable modulus elastoplastic strength reduction method,the real deformation field can be obtained.Aiming at the deficiency of the current searching methods for slip surface and considering the features of deformation and stress of slopes as well as formation mechanism and characteristics of slip surface,how to determine the slip surface by deformation field and stress field of slope is studied.Three methods are discussed:(1) the most unfavorable sliding surface is determined by displacement gradient;(2) according to the computational features of FLAC,the characteristics are adopted that the nodal velocity of stable region is zero while the nodal velocity of slip region is very large to determine the slip surface;(3) referring to inclinometer concept in slope monitoring,the nodal displacement is tracked,and the nodes with displacement mutation are taken as the points of slip surface,then the critical slip surface is the fitted curve of those points.A clay slope with weak layer is analyzed,and the slip surfaces by the above three methods are nearly the same.Compared to the traditional limit equilibrium methods,these three methods can be applied in homogeneous slopes and heterogeneous slopes.

关 键 词：变模量弹塑性 强度折减法 边坡 变形场和应力场 临界滑动面 

分 类 号：TU43[建筑科学—岩土工程]