Numerical simulation of flow failure of geomaterials based on fluid dynamics

A numerical method is developed for the prediction of large deformations associated with a geomaterial flow during the occurrences of such geo-disasters as landslides and slope failures. The geomaterial is modeled as a viscous fluid, where a Bingham type constitutive model is proposed based on Coulomb's failure criterion and the viscosity is derived from the cohesion and friction angle. Numerical experiments on a 2D gravitational flow of a geomaterial column show that the constitutive model performs well. For solving Navier-Stokes's equations, Constrained Interpolated Profile (CIP) scheme is utilized, which is able to efficiently treat solid, liquid and gas together and has been successfully applied to problems in fluid dynamics. To prevent numerical instabilities due to a large Bingham viscosity, an implicit calculation procedure is proposed to calculate the viscous forces in the CIP. The method is finally used to simulate an earthquake-induced landslide that took place on May 26th, 2003 in the Northern part of Miyagi Prefecture in Japan. Results from soil-slump tests on the samples from the landslide site are used for determining the parameters in the simulation. Good agreements between the calculated and the observed results are obtained.