Analysis of the distributions of stress in natural ridge forms: implications for the deformation mechanisms of rock slopes and the formation of sackung

Stress distributions in general asymmetric ridge forms, derived from 13 ridges in British Columbia and Colorado, are modelled in two dimensions with a finite difference method. In each of the 13 ridges, sackung (scarps, tension cracks, trenches) can be found. Spatial correlations between stress concentrations and these sackungen landforms are investigated for the mean ridge forms. Rock mass properties for the modelled ridges are developed using the Hoek-Brown criterion and the Geological Strength Index (GSI). Gravity loading and combined gravity-tectonic loading on the ridge forms are considered. The importance of representing in situ rock masses with an elastoplastic (as opposed to elastic) constitutive criterion is discussed. The resulting stress distributions for the three general ridge classes indicate that different processes are responsible for the formation of sackungen landforms and slope deformations in each type of ridge.