A critical-state constitutive model for considering the anisotropy in sandy slopes

In this paper, a novel approach that associates the behavior of granular material with the void space and plastic deformations is applied to evaluate the strength changes with the loading directions. For this target, a critical state constitutive model based on Imam et al. ( 2005 ) is adopted to quantify the mobilized strengths. In this strategy, the tensor of fabric becomes co-direction with the tensor of loading to reach a constant magnitude of the unit at the compact state. In this state, the interlocks among the sand particles are strictly high, so that slip cannot happen. It is supposed that at this stage, the sample’s reaction to the stress changes is isotropic. The validation is performed against some datasets of monotonic element tests and cyclic triaxial tests. Then, the different aspects of the proposed model and their influences on the dynamic-induced displacements in the slopes are investigated. The results reveal the prominent role of the fabric in capturing the anisotropic behavior of sand, especially in slope stability analysis. Also, the results show that fabric evolution significantly affects the strength characteristics and the deformation of slopes. In the bedding plane orientations from 45 to 90°, the extended model ensures a higher magnitude for displacements in comparison to the basic model. The lack of considering the evolution of the fabric to the void ratio leads to a non-conservative analysis of the slopes, and it is a critical item in determining the displacements in dynamic loadings.