Distinct element method analyses of idealized bonded-granulate cut slope

This paper presents a numerical study of idealized bonded-granulate cut slope subject to sudden strength reduction. A 2-D Distinct Element Method (DEM) has been used to carry out a simulation of full-process slope failure with focus on very-rapid and extremely-rapid landslide process. The numerical results show that during the landslide process: (1) the soil moves either in a rather random/chaotic way (diffuse failure) or in different curved shear bands (localized failure). The soil close to slope surface moves along downward slope while the soil close to the slope toe moves significantly in the horizontal direction. The landslide experiences very rapid flow most of the time, with its maximum velocity increaseing obviously with time at first to its peak value, then decreasing gradually to zero. (2) The soil close to slope undergo a repeated loading and unloading process, and an evident rotation of principal stresses. Their stress state may arrive slightly over the peak strength envelope as a result of extremely rapid flow. (3) There is little grain-size effect for the grains at low velocity, but an evident grain-size effect for the grains at high velocity, with large-size grains tending to move fast. (4) The post-failure inclination is much smaller than the peak/residual internal friction angle of the material. The post-failure slope surface passes through the centre of the initial slope surface instead of the initial slope toe.