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

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.

Key words:bentonite;unsaturated soil;constitutive model;multi-scale pore structure