Constitutive and Numerical Modeling for Analysis of Permanent Deformations of Soil Structures

这项研究的目标是建立一个计算高效的数学模型，用于分析饱和土结构在地震期间和地震后的永久变形。这是一个由加州大学戴维斯分校和乔治华盛顿大学的主要研究人员参与的团队研究项目。该模型基于有限变形两相混合理论。它涉及到对已验证的塑性本构模型的改进，并将其应用到现有的有限元程序中。其目的是增强该程序的能力，以准确预测饱和土壤液化前和液化期间的行为。本构模型正在扩展，以表示颗粒土在中等高有效应力和极低有效应力下的行为，从而有可能模拟土壤在液化前和液化期间的行为。这是通过考虑当土壤接近非常低的有效应力时土壤组构的变化来实现的。所建立的有限元模型被用于研究液化引起的地面大位移的机理，包括饱和土地基的侧向扩展和沉降。提高预测强地面震动后地基的侧向扩展的能力将对减轻地震的影响做出重大贡献。

The objective of this research program is to develop a computationally efficient mathematical model for analyzing the permanent deformation of saturated soil structures during and following an earthquake. This is a group research project involving principal investigators at the University of California-Davis and George Washington University.The model is based on a finite deformation two-phase mixture theory. It involves the improvement and implementation of an already-validated plasticity constitutive model into an existing finite element code. The goal is to enhance the capability of this code to accurately predict the behavior of saturated soils prior to and during liquefaction. The constitutive model is being extended to represent the behavior of granular soils, both at moderately high and at very low effective stresses, making it possible to simulate the behavior of soil prior to and during liquefaction. This is achieved by considering the change of soil fabric as the soil approaches very low effective stresses. The resulting finite-element model is used to study the mechanism of liquefaction-related large ground displacements, including the lateral spreading and settlement of saturated soil deposits.Advancing the ability to predict the lateral spreading of soil foundations following strong ground shaking will be a significant contribution to mitigating the effects of earthquakes.