Abstract：Before slope slides at a high velocity，the sliding resistance is corresponded to the shear strength in limit equilibrium state. Once the locked segment is suddenly snipped，half of the original sliding resistance is released owing to peak-residual strength drop，and the elastic strain energy accumulated in the locked segment would be converted into the kinetic energy of the sliding mass. Thus the sliding mass has a high velocity in biginning. After that，as potential energy is convetted into the kinetic energy，the sliding mass would slide still with a higher velocity. Based on triaxial tests，a study is performed on strength and deformation characteristics of the basaltic rock mass from the Touzhai high-speed landslide. The results show that there is remarkable difference between peak shear strength and residual shear strength，and the drop rate of the shear strength is about 50%. The muzzle velocity of the Touzhai landslide is predicted on the basis of the tests.
