Scale-Dependent Rockslide Mechanisms, with Emphasis on the Role of Pore Fluid Vaporization

ABSTRACT Very large-scale rockslide mechanisms may be different from those involved in medium- and small-scale slides, and in that case similitude relationships alone provide an invalid means of comparison. This paper considers the application of similitude to medium-scale rotational slides, to large-scale bedding plane slips, and to the question of rock mass avalanches. The possibility of “fluidization” effects are discussed in regard to the avalanche question; it is shown that some collective effect of mass must exist in avalanches, which because of its poorly understood nature, cannot yet be described by similitude laws. Similarly, with large-scale slides, vaporization of water by frictional heating may be a most important scale-dependent mechanism. Such a mechanism can exist only in large slides, because with small slides the required displacement in order to achieve vaporization would be larger than the possible displacement of the slide mass.