一种新型结构性土三维本构模型

在NAKAI等基于应力张量t_(ij)和修正剑桥模型建立的能够描述中主应力影响且适用于描述正常固结土强度和变形规律的三维本构模型的基础上,通过引入能够描述土体密实度的状态变量ρ和土体黏结效应的状态变量ω,提出了适用于描述结构性土强度和变形规律的新型结构性三维本构模型。这一模型具有以下特点:结构性土三维本构模型在正常固结土的三维本构模型的基础上仅增加一个材料参数的情况下能够较好地描述三维应力状态下试样排水与不排水剪切特性、固结特性、围压对应力路径和应力应变曲线的影响及平均应力、偏应力增大时出现的应力路径可逆性等特点。应用新型结构性土三维本构模型对粉质黏土的固结试验和三轴剪切试验进行模拟计算,验证了其在模拟结构性土特征方面的可行性。

A new type of 3-D constitutive model for structured soil

On the basis of the 3-D constitutive model， which can describe the principle stress effect and is suitable for describing both the strength and the deformation law of the normal consolidated soil， established by NAKAI etc. in accordance with the stress tensor tij and the modified Cam-clay model， a new type of structured 3-D constitutive model suitable for describing the strength and deformation law of structured soil is proposed herein through introducing in the state variable ρ which can describe soil compactness and the state variable ω which can describe bond effect of soil. This model has the following performances： based on the 3-D constitutive model for the normal consolidated soil， the 3-D constitutive model for structured soil can better describe the characteristics of soil sample under 3-D stress state， such as the drained and un-drained shear characteristics， the consolidation performance， the effect from surrounding pressure on stress path and stress-strain curve as well as the reversibility of stress path occurred when the increases of mean stress and deviator stress， etc. under the condition of only adding one material parameter. The type of 3-D constitutive model for structured soil is applied to the simulative calculations for the consolidation test and triaxial shear test made on silty clay， and then the application feasibility of the model in the aspect of simulating the characteristics of structured soil is verified as well.