2017 Volume 5 Issue 2 Pages 62-65
An adaptive substepping explicit integration scheme is proposed for a subloading surface plasticity (SSP) model for unsaturated soils. The constitutive laws of the SSP model are established in the space of Bishop’s effective stress and effective degree of saturation (Θ). The model includes a convex subloading surface in the p-q plane and a nonconvex subloading surface in the p-Θ plane. The convex/nonconvex subloading surface in the model may cause problems of incorrect loading-unloading decisions during the stress update. A Double Cosine loading-unloading decision method (DC method) is revised and embedded into the explicit integration. The local error of the effective degree of saturation is introduced in the error control for each substep. The performance of the DC method is discussed. The importance of involving the effective saturation in the error control is also demonstrated via numerical examples.
