A Multi-Phase Coupled FE Analysis Using an Elasto-Viscoplastic Model for Unsaturated Soil
A Multi-Phase Coupled FE Analysis Using an Elasto-Viscoplastic Model for Unsaturated Soil
复制标题
使用弹粘塑性模型对非饱和土进行多相耦合有限元分析
DOI：
10.1061/40870(216)10
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
N. Yamasaki
中科院分区：
文献类型：
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作者：
F. Oka;T. Kodaka;S. Kimoto;Young Seok Kim;N. Yamasaki
本文建立了考虑吸力作用的非饱和粘性土弹粘塑性本构模型，并采用弹粘塑性模型进行了土-水-空气三相耦合分析。本文提出的本构模型采用混合理论的平均骨架应力作为有效应力。因此，用平均骨架应力代替有效应力，并在本构模型中引入吸力效应，可以从饱和土模型入手构建非饱和土模型。吸力减小引起的坍塌行为可以用超固结边界面、静态屈服面和粘塑性势面收缩来描述。利用多孔介质理论，在连续介质力学的框架内对多相材料进行了数值分析。该理论是Biot的饱和土两相混合理论的推广。本文采用基于非线性有限变形理论的多相土控制方程，建立了一种土-水-气三相耦合有限元方法。平均骨架应力定义为两种流体的总应力和平均压力之差，并用于所提出的弹粘塑性本构模型。采用van Genuchten（1980）型方程作为液体饱和度与吸力压力之间的本构方程。对平面应变条件下的不排水不枯竭压缩进行了数值模拟，并从应变局部化和吸力效应两方面评价了所提方法的适用性。
The present study addresses an elasto-viscoplastic constitutive model which considers the effect of suction in unsaturated clayey soil and a soil-water-air three-phase coupled analysis using the elasto-viscoplastic model. The proposed constitutive model adopts the average skeleton stress for the effective stress from mixture theory. Hence, it has become possible to construct a model for unsaturated soils starting with a model for a saturated soil by substituting the average skeleton stress for the effective stress and introducing for the suction effect into the constitutive model. Furthermore, the collapse behavior, which is brought about by a decrease in suction can be described by the shrinkage of the overconsolidation boundary surface, the static yield surface, and the viscoplastic potential surface. A numerical analysis for multiphase materials is conducted within the framework of a continuum mechanics approach through the use of the theory of porous media. The theory is a generalization of Biot's two-phase mixture theory for saturated soil. A soil-water-air three-phase coupled finite element method has been developed in the present study using the governing equations for multi-phase soil based on the non-linear finite deformation theory. The average skeleton stress is defined as the difference between the total stress and the average pressure of the two fluids and is used in the proposed elasto-viscoplastic constitutive model. A van Genuchten (1980) type of equation is employed as the constitutive equation between the liquid saturation and the suction pressure. Numerical simulations of unexhausted-undrained compression are conducted under plane strain conditions, and the applicability of the proposed method is evaluated with respect to strain localization and the effect of suction.