土体应变局部化判别准则与峰值后的力学性状

Criterion Governing Inception of Strain Localization and Post-bifurcation Responses in Soils

针对土体应变局部化的理论研究现状 ,从土体局部化产生的判别准则及其峰值后土体力学性状的数值模拟两方面入手 ,探讨传统应变局部化理论目前尚存在的问题 .研究表明 ,轴对称条件下的土体失稳现象是一种扩散性的分叉特性 ,变形局部化理论难以解释其产生的机理 ;变形分叉的非共轴理论能够改善传统变形分叉理论的局限性 ;Pietruszczak等和笔者给出的复合体理论可有效地模拟土体峰值后的力学性状 .

It is important to get an insight into in the onset of deformation localization of the soil and its development process.In this paper,two key aspects are discussed.One is criterion governing the occurrence of strain localization.The other is description of the post-bifurcation response in soils.The authors'recent studies show that employing non-axiality into constitutive relation can overcome inevitable defects of traditional bifurcation theory.The authors' researches also verify that the instability under axisymmetric conditions is a diffuse bifurcation instead of strain localization.It also can be seen that the homogenization approach given by Pietruszczak et al and the authors can reasonably describe post- failure responses in soils.