Simulation and experimental study of soil behaviors under principal stress rotations

This paper presents an elastoplastic soil model considering the Principal Stress Rotation (PSR) and an experimental facility associated with the PSR. The model is developed on the basis of a well-established kinematic hardening soil model using the bounding surface concept. The impact of the stress rate generating the PSR is treated independently, with its own hardening and flow rules. The new PSR model gives better simulations of soil behaviors under loading paths involving the PSR than the base model without special consideration of the PSR. A new experimental facility, Variable Direction Dynamic Cyclic Simple Shear (VDDCSS), manufactured by GDS is also introduced. It can independently exert two shear stresses to a soil specimen along two orthogonal directions. Test results indicate that directions of shear consolidation have a great impact on following undrained soil behaviors under both monotonic and cyclic shearing.