A possible mechanism of movements of an ancient clayey landslide

The displacement rate of the considered ancient clayey earth slide varies noticeably along its longitudinal axis, however it is practically constant from the slip surface to the ground along four inclinometer profiles. In this paper, the displacement uniformity and the absence of viscous deformation are discussed and justified. The comparison among the theoretical shear stress distribution –within the landslide body and on the slip surface – the experimental peak shear strength and the residual shear strength shows that shear stresses are lower than or equal to residual strength. This latter, in turn, is much lower than the peak strength. Furthermore, long term shear tests carried out under controlled shear forces suggest that only primary creep occurs at shear stresses lower than residual strength. So, the landslide displacements can be hypothesized uniform in each entire transversal section of the channel.