地基渐进破坏及极限承载力的Cosserat连续体有限元分析

Finite element analysis of Cosserat continuum for progressive failure and limit bearing capacity of soil foundation

利用Cosserat连续体理论和所发展的有限元数值方法,模拟了地基由应变软化引起的以应变局部化为特征的渐进破坏过程,并从等价塑性应变的发展变化,阐述了渐进破坏过程对所能发挥的极限承载能力的影响。结果表明,Cosserat连续体模型能有效地模拟由应变软化引起以应变局部化为特征的渐进破坏现象,对地基等土工结构物有必要进行渐进破坏分析。同时指出,在求解软化型土体地基的极限承载力时,如果仍按传统的极限平衡或极限分析理论进行分析,可能得出偏于危险的结果。

Based on the derived finite element formulations of Cosserat continuum, progressive failure phenomena of the soil foundation, characterized by strain localization due to strain softening, are numerically analyzed. The influence of progressive failure process on the limit bearing capacity is illustrated by the developments of equivalent plastic strain. Numerical results demonstrate the effectiveness of the Cosserat continuum finite elements in preserving the well-posedness of the localization problem and simulating the progressive failure phenomena characterized by strain localization due to strain softening, necessity of the progressive failure analysis for earth structures such as the soil foundation etc.. Simultaneously it is pointed out that the unsafe results are to be obtained as the limit bearing capacity of strain softening soil foundation is analyzed by traditional theories of limit equilibrium and limit analysis.