A 3D bounding surface model for rockfill materials

A 3D bounding surface model is established for rockfill materials, which can be applied to appropriately predict the deformation and the stabilization of rockfill dams. Firstly, an associated plastic flow rule for rockfill materials is investigated based on the elaborate data from the large-style triaxial compression tests and the true triaxial tests. Secondly, the constitutive equations of the 3D bounding surface model are established by several steps. These steps include the bounding surface incorporating the general nonlinear strength criterion, stress-dilatancy equations, the evolution of the bounding surface and the bounding surface plasticity. Finally, the 3D bounding surface model is used to predict the mechanical behaviors of rockfill materials from the large-style triaxial compression tests and the true triaxial tests. Consequently, the proposed 3D bounding surface model can well capture such behaviors of rockfill materials as the strain hardening, the post-peak strain softening, and the volumetric strain contraction and expansion in both two- and three-dimensional stress spaces.