基坑放坡开挖破坏性状大变形有限元分析

基于任意拉格朗日–欧拉(ALE)有限元方法,采用理想弹塑性本构模型(不考虑软化)和考虑应变软化的本构模型以及Mohr-Coulomb屈服准则,对平面应变条件下软土均质地基上的基坑放坡开挖进行数值模拟,并对非软化及软化模型的结果进行对比。研究表明:考虑应变软化分析的结果同非软化分析的结果有较明显的不同,在基坑开挖达到一定深度后,土体剪切带发展方向不同,考虑应变软化时基坑顶部比基坑底部早达到塑性状态,而非软化分析中则是基坑底部早达到塑性状态;同时从图形化分析角度讲,非软化分析中剪切带的贯通过程较为明显,而软化分析中其剪切带的贯通过程则要复杂。非软化分析得到的结果是偏不安全的。

Large deformation finite element analysis on excavated slopes

Based on the arbitrary Lagrangian-Eulerian finite element method combined with Mohr-Coulomb yield rule,numerical analysis on the excavated slopes was presented by using ideal elasto-plastic model or that considering strain-softening of soils.The results were quite different by using these two different models.The top of the slop reached the plastic state earlier than the bottom for the model considering strain-softening,and contrariwise,the bottom reached earlier for the ideal elasto-plastic model.From the point of view of graphic analysis,the development of shear-band was more obvious for the ideal the elasto-plastic model,and was more complex for the model considering strain-softening.The results calculated by the ideal elasto-plastic model will lead to unsafety.