Laboratory Test and Constitutive Model for Quantifying the Anisotropic Swelling Behavior of Expansive Soils

Abstract

Expansive soils exhibit directionally dependent swelling that traditional isotropic models fail to capture. This study investigates the anisotropic swelling characteristics of expansive soil with a medium swelling potential through the use of modified oedometric testing. Vertical swelling strains can reach up to 1.71 times that of the horizontal movements, confirming intrinsic anisotropy. A nonlinear elastic constitutive model incorporates vertical and horizontal elastic moduli with respect to matric suction to characterize anisotropy. Three elastic parameters were determined through the experiments, and predictive equations were developed to estimate the unsaturated moduli. The constitutive model and predictive techniques provide practical tools to better assess expansive soil pressures considering anisotropy, offering guidelines for utilization and design. The outcomes advance understanding of these soils’ directionally dependent behavior and stress–strain–suction response.

Investigation into the Characteristics of Expansion and Compression Deformation of Interbedded Weak Expansive Rocks in Water Immersion

“…As one of the special structures, interbedded rocks are characterized by the repeated alternation of two or more lithology strata due to the continuous change in the sedimentary environment, which is usually manifested as the difference in rock hardness [1]. Compared to a single homogeneous rock mass, interbedded rock mass exhibits a high degree of anisotropy [2]. Due to the change in boundary conditions such as a complex in situ stress environment, excavation, and support, and the influence of environmental factors such as rainfall, evaporation, and the freeze-thaw cycle, its deformation and failure mechanism is very complex.…”