A Note on the Stability of Cuttings in Normally Consolidated Clays

Abstract

Synopsis It is shown that the factor of safety against undrained failure of a slope cut in an ideal normally consolidated clay whose undrained shear strength increases linearly with depth, depends not upon the height but only upon the inclination of the slope, the ratio and the bulk density of the clay. The calculation of the factor of safety is facilitated by the use of a stability number which is related to the slope inclination alone: this relation is presented graphically in the Paper. Il est démontré que le coefficient de sécurité qui joue dans la rupture d'une pente taillée dans une argile normalement consolidée dont la résistance au cisaillement à teneur en eau constante augmente d'ne façon linéaire avec la profondeur, dépend non de la hauteur mais seulement de l'angle de la pente, du rapport et de la densité apparente de l'argile. Le calcul du coefficient de sécurité est rendu plus arisé par l'emploi d'un facteur de stabilité qui n'est lié qu'a l'angle de la pente: ce rapport est représenté graphiquement dans l'article.

Limit analysis solutions for three dimensional undrained slopes

“…3. The shear strength c u is assumed to increase linearly with depth as is the case in normally consolidated clays [62]. Therefore, c u is given by…”

The analytical method in soil mechanics

“…They showed that as long as a just stable slope is not flatter than about Y, the solution to this problem based on a worst circle (Gibson and Morgenstern, 1962) is very little in error.15…”

Earthflows at the Beattie Mine Quebec, Canada

“…It is interesting to note, however, that if the slopes were cut to 4:1 as planned, they would be critical according to the analysis proposed by Gibson and Morgenstern (1962) and using the c/p measured in the triaxial test. It is thought that the clay would have been nearly norinally consolidated at that stage.…”