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传统的砂土本构理论不适用于密度和围压变化较大的情况,并且由于隐含了应力和塑性应变率的共轴条件,无法客观描述主应力轴旋转试验中的非共轴现象。本文基于材料状态相关砂土临界状态概念,将Pietruszczak和Stolle(1987)所提出的砂土本构模型进行了改进,并在模型中引入非共轴塑性流动理论来研究砂土的非共轴变性特性。通过对常规三轴试验和空心圆柱试验的数值模拟,表明模型不但能够合理反映初始密实度及有效围压对材料变形特征的影响,还能有效预测主应力轴旋转过程中主应力和主应变率的方向变化规律。
The traditional constitutive theory of sand is not suitable for large changes of density and confining pressure. Due to the co-axial conditions implying stress and plastic strain rate, it is not possible to objectively describe the non-coaxial phenomenon in the principal stress axis rotation test. In this paper, based on the concept of material-state-related criticality of sand, the sand constitutive model proposed by Pietruszczak and Stolle (1987) is improved. Non-coaxial plastic flow theory is introduced into the model to study the non-coaxial deformation of sand characteristic. Through the numerical simulation of the conventional triaxial test and the hollow cylinder test, the model not only can reasonably reflect the influence of the initial compactness and the effective confining pressure on the deformation characteristics of the material, but also effectively predict the principal stress and the main strain rate during the rotation of the principal stress axis The direction of change.