超固结非饱和土本构关系的三维化方法

Three-dimensional method for constitutive relationship of overconsolidation unsaturated soil

本构模型的三维化对反映材料在三维应力状态下的力学特性具有重要意义。在π平面上,广义Mises三维化方法不能反映应力洛德角对材料变形和强度的影响,g(θ)等方法不能合理地反映应力水平对变形和强度的影响。变换应力三维化方法考虑了应力洛德角影响,数学表达简洁,不增加模型参数,便于计算应用。将作者等人所提的超固结非饱和土本构模型与基于SMP(spatially mobilized plane)的变换应力方法结合,实现了超固结非饱和土的三维化,达到了从剪切屈服到剪切破坏的连续过渡。该模型能够描述不同应力洛德角下超固结非饱和土的硬化、软化、剪胀特性,并与试验数据进行了对比。

The generalization of constitutive model has great significance in describing the three-dimensional mechanical behaviors of soil. The Mises criterion cannot reflect the effect of Lode＇s angle on deformation and strength of material and the g（O） method cannot reflect the effect of stress level on those on the π plane. To overcome these problems, an approach named transformed stress method considering the effect of Lode＇s angle is proposed without adding any extra parameter and can be simply applied to numerical analysis. Combining the constitutive model proposed by authors with the transformed stress method based on SMP（spatially mobilized plane）, three-dimension of overconsolidated unsaturated soil is realized; continuous transition from shear yield to shear failure is achieved. Many characteristics including hardening, softening and dilatancy of overconsolidated unsaturated soil with different Lode＇s angles are described and compared with test data.