Dynamic simulation of rockslide-debris flow based on an elastic–plastic framework using the SPH method

To simulate the motion process of a rockslide-debris flow that behaves like a solid in a small deformation regime and a fluid in an extremely large deformation regime, such as that of the Guanling rockslide in China on June 28, 2010, we proposed a dilatant rheology model that bridges this mechanical behavior of such flows, using the Guanling rockslide as an example. In our model, the adjustment of the material isotropic pressure when plastic deformation occurred was based on the plastic potential theory of solid mechanics, and the shear stress tensor was calculated based on the Drucker–Prager yield criterion and the strain-rate tensor. Furthermore, the Jaumann rate was adopted to maintain the stress frame consistent with the strain and rotation information. The boundary condition in our simulation was based on the dynamic boundary condition, and the boundary particles were described by the Bingham model rather than the proposed model, which differs from the usual treatment. Furthermore, the inverse distance weighting method was applied to evaluate the rockslide depth at different stages. Finally, a three-dimensional (3D) representation of the velocity, depth, kinetic energy, and density of the Guanling rockslide-debris flow was obtained using the dilatant rheology model, which revealed that surface mass fluidization lagged behind sliding plane mass fluidization in the studied flow. The simulation results indicate that, with respect to simulating the Guanling rockslide-debris flow, the proposed model employing 3D smoothed-particle hydrodynamics was superior to and more detailed than the incompressible fluid model using the depth-integrated method.