Mechanical properties and constitutive model for artificially structured soils with an initial stress-induced anisotropy

A series of triaxial compression tests was performed on artificially structured soil samples with an initial stress- -induced anisotropy at confining pressures of 25, 37.5, 50, 100, 200, and 400 kPa. Based on the results of these tests, a constitutive model for structured soils with initial stress-induced anisotropy was formulated. In the proposed model, the initially anisotropic structured soils are regarded as heterogeneous materials composed of bonded blocks and weaker bands. The bonded blocks (denoted as bonded elements) are described as transversely isotropic elastic– brittle materials, while the weaker bands (denoted as frictional elements) are described by the Lade–Duncan model of elastic–plastic materials. Based on the homogenization theorem for heterogeneous materials, and the introduction of structural parameters such as the breakage ratio and the local strain coefficient, the non-uniform distribution of stress and strain within a representative volume element was obtained. Finally, the parameters of the model were determined based on experimental results. The model was verified with test results, demonstrating that it can effectively capture many important features of artificially structured soils with an initial stress-induced anisotropy.