ABSTRACT
Large rockslides appear to start moving at a rapid velocity. The amount of strain energy released by the shear strength drop of the rocks on the eventual failure surface while the locked-up segment of slope deformation sheared all at once was evaluated by using the Griffith energy balance approach and an expression of the onset velocity of rockslide was derived. The mechanism of onset of large rockslides has been the subject of considerable interest in several decades. The chapter attempts to illustrate quantitatively a mechanism to explain a behavior of the rockslide initiation caused by peak-residual strength drop of rocks. As far as the onset effect of rockslide caused by the peak-residual strength drop is concerned, more attention is focused on a breakdown process of the middle locked-up segment. In particular, if taking into the potential energy transformed along the inclined slip surface into the kinetic energy account, the flying velocity of rockslide will be much greater.
