Influence of kinematics on landslide mobility and failure mode

Geometry of discontinuities greatly influences the kinematic behavior of slopes and landslides. Discontinuous deformation analysis (DDA) is used here to analyze two typical examples of slope failure, demonstrating that accurate representation of the geometry of the discontinuities is essential for identification of kinematically correct failure modes. Then, static stability analyses of the Vaiont, Italy, landslide of October 9, 1963 are used to show that the DDA results compare favorably with previously published limit equilibrium studies using similar geometries, and that the location and number of discontinuities have a significant effect on the predicted stability and failure velocities of the landslide. Dynamic DDA simulations of the Vaiont landslide show that the peak velocity increases up to 50% as the number of blocks increases, indicating that internal disintegration of the landslide mass results in increasing acceleration and higher peak velocity. DDA analyses simulating pore pressure rise resulting from frictional heating of the basal slide plane show that the peak velocity similarly increases up to 50% as the number of blocks increases. The magnitude of the increase in peak velocity as a result of disintegration (i.e., increasing number of blocks) suggests that as much attention should be paid to the geometry of discontinuities as is typically paid to shear strength and pore pressure.