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极限分析有限元法讲座--Ⅱ有限元强度折减法中边坡失稳的判据探讨
引用本文:赵尚毅,郑颖人,张玉芳.极限分析有限元法讲座--Ⅱ有限元强度折减法中边坡失稳的判据探讨[J].岩土力学,2005,26(2):332-336.
作者姓名:赵尚毅  郑颖人  张玉芳
作者单位:1. 后勤工程学院,土木工程系,重庆,400041
2. 铁科院深圳铁科岩土工程公司,广东,深圳,518034
摘    要:边坡失稳,滑体滑出,滑体由稳定静止状态变为运动状态,同时产生很大的且无限发展的位移,这就是边坡破坏的特征。有限元中通过强度折减使边坡达到极限破坏状态,滑动面上的位移和塑性应变将产生突变,且此位移和塑性应变的大小不再是一个定值,有限元程序无法从有限元方程组中找到一个既能满足静力平衡又能满足应力-应变关系和强度准则的解,此时,不管是从力的收敛标准,还是从位移的收敛标准来判断有限元计算都不收敛。塑性区从坡脚到坡顶贯通并不一定意味着边坡破坏,塑性区贯通是破坏的必要条件,但不是充分条件,还要看是否产生很大的且无限发展的塑性变形和位移,有限元计算中表现为塑性应变和位移产生突变。在突变前计算收敛,突变之后计算不收敛,表征滑面上土体无限流动,因此可把有限元静力平衡方程组是否有解,有限元计算是否收敛作为边坡破坏的依据。-

关 键 词:边坡稳定分析  有限元强度折减法  失稳判据
文章编号:1000-7598-(2005)02-0332-05
收稿时间:2004-08-02
修稿时间:2004年8月2日

Study on slope failure criterion in strength reduction finite element method
ZHAO Shang-yi,ZHENG Ying-ren,ZHANG Yu-fang.Study on slope failure criterion in strength reduction finite element method[J].Rock and Soil Mechanics,2005,26(2):332-336.
Authors:ZHAO Shang-yi  ZHENG Ying-ren  ZHANG Yu-fang
Institution:1.Department of Civil Engineering, Logistical Engineering University, Chongqing 400041, China; 2 Shenzhen TieKe Geotechnical Engineering Co. Ltd., Shenzhen 518034, China
Abstract:Slope collapse and the slide body come into moving state from stable static state simultaneously, and are accompanied by a dramatic increase in displacement of slide body. Furthermore, the displacement is not a definite value, but an infinite increase. This is the definition of overall collapse of a slope. In finite element model, the slope reaches instability with the strength reduction, value of the nodal displacement just after slope failure has a sudden change compared to the one before failure. This actually means that no stress distribution can be achieved to satisfy both the yield criterion and global equilibrium. Slope failure and numerical non-convergence take place at the same time. An element stress reaching the yield criterion state not always means that infinite “plastic flow” occurred. It is determined by boundary condition. The plastic zone developed from slope toe to top not means the overall collapse occurred. On the other hand, the distribution of plastic zone was influenced by many factors such as Poisson's ratio, flow rule, etc. So non-convergence in finite element program can be taken as a suitable evaluating criterion of slope failure. Through a series of case studies, the applicability of the proposed method was clearly exhibited.
Keywords:slope stability analysis  strength reduction FEM  criterion of slope failure
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