考虑多尺度孔隙耦合效应的非饱和膨胀土本构模型

A Coupled Constitutive Model of Unsaturated Expansive Soils Considering Multi-Scale Pore Structures

摘要:

颗粒型膨润土材料具有颗粒间孔隙、集合体间孔隙和集合体内孔隙等多尺度孔隙结构特征，传统非饱和膨胀土双孔模型（BExM）难以准确描述其宏观力学行为。在现有BExM模型的理论框架基础上，从颗粒型膨润土材料的三重孔隙结构出发，通过双加载屈服面方程和宏微观耦合效应函数表征膨润土颗粒混合物的多尺度孔隙弹塑性变形行为及其相互耦合关系。通过对比试验数据与模型模拟结果发现，模型可较好地描述非饱和颗粒型膨润土材料的膨胀力特征、膨胀变形特征以及宏微观孔隙结构演化规律。

Abstract:

Granular bentonite materials have a multi-scale pore structure （i.e.， inter-pellet pores， inter-aggregate pores， and intra-aggregate pores）， which makes it difficult for the traditional two-porosity constitutive model to accurately describe the mechanical behavior. In this paper， a constitutive model considering triple-porosity structures was proposed based on the BExM model for unsaturated expansive soils. The elastic-plastic deformation behaviors and the coupling effects of multi-scale pore structures were described by two yield-surface equations and two coupling functions， respectively. A comparison of the measured and predicted results shows that the proposed model could well describe the swelling pressure property， the swelling deformation behavior， and the pore evolution characteristic of unsaturated granular bentonite materials.