The mechanism of block collapse formation upon activizing the deep landslide in terms of dissipative structures

The paper considers the collapse mechanism in the back part of a new landslide block upon its separation from the bedrock massif. It is shown that in the course of failure preparation, two blocks participate, i.e., the elements of dissipative structures that appear in the stress field of the bedrock landslide-prone massif. The study reviews the conditions of failure formation, stress distribution (in accordance with the Laplace solutions for axisymmetric thin-walled shells) inside the block and along its boundary surfaces (shells) when the massif limit state forms. The mechanism of block separation (discontinuity of the massif) along the shell and specifics of soil deformation are also analyzed. The equilibrium in the head scarp massif is usually disturbed due to soil discontinuity forming along the earlier virtual circular-cylindrical shell of the first block, adjacent to the slope edge. In this case, the landslide block moves according to the detrusive mechanism. In addition to the ordinary process, the delapsive movement is also possible, with activating massif displacements in the lower part (washing-out, sliding, underworking of the lower part of the slope). This landslide activation favors to more intensely decreasing stresses in the back block shell in the head scarp massif, and consequently, to widening of the separation crack. At that moment, the influence of the subsequent block becomes evident, as displacements take place along the frontal block shell and a failure massif forms between the specified boundaries. The examples of failure-blocks formation when the landslide process activates on the natural slopes and quarry slopes are given.