考虑剪切中主应力方向的砂土本构模型

Constitutive model of sand considering shearing orientation of principal stress

考虑状态依赖性的弹塑性本构模型是当前现代砂土本构理论发展的一个主流方向,目前所引用的状态参量虽能够反映孔隙比与平均有效应力的联合效应,但尚不能反映剪切过程中的主应力方向对砂土应力-应变关系的影响。大量复杂应力条件下的空心扭剪试验证明,剪切中的主应力方向对砂土的变形和强度特性具有重要的影响。本文基于考虑砂土状态依赖性的本构理论,提出了一个含有主应力方向的砂土状态参量,并将其同时引入剪胀方程和塑性模量,以此为基础建立了一个能够反映剪切中主应力方向的砂土弹塑性本构模型。通过同相关试验数据的对比和分析,验证了该模型可以较好地模拟砂土在不同主应力方向下的应力-应变关系。

The elastoplasticity constitutive model considering the state-dependent is a prevalent direction for the development of modern constitutive sand theory. The current proposed state parameters can reflect the conjunct influence of the void ratio and mean effective stress, however the effect of the shearing orientation of principal stress on the stress-strain relationship of sand is still not expressed. It has been displayed that the orientation of principal stress has a significant impact on deformation and strength of sand through a large number of hollow torsion shear tests. Based on the theory of state-dependent constitutive model, a new state parameter considering the shearing orientation of principal stress is proposed and introduced into dilatancy equation and the plastic hardening modulus expression to develop a new constitutive model for sand which can display the influence of the shearing orientation of principal stress. By comparison with the related experimental data and analyzing, the method on simulating the stress-strain relationship under the different shearing orientation of principal stress is proved to be correct and accurate.