A numerical study of flexural buckling of foliated rock slopes

The occurrence of foliated rock masses is common in mining environment. Met hods employing continuum approximation in describing the deformation of suc h rock masses possess a clear advantage over methods where each rock layer and each inter-layer interface (joint) is explicitly modelled. In devising such a continuum model it is imperative that moment (couple) stresses and i nternal rotations associated with the bending of the rock layers be properl y incorporated in the model formulation. Such an approach will lead to a Co sserat-type theory. In the present model, the behaviour of the intact rock layer is assumed to be linearly elastic and the joints are assumed to be el astic-perfectly plastic. Condition of slip at the interfaces are determined by a Mohr-Coulomb criterion with tension cut off at zero normal stress. Th e theory is valid for large deformations. The model is incorporated into th e finite element program AFENA and validated against an analytical solution of elementary buckling problems of a layered medium under gravity loading. A design chart suitable for assessing the stability of slopes in foliated rock masses against flexural buckling failure has been developed. The desig n chart is easy to use and provides a quick estimate of critical loading fa ctors for slopes in foliated rock masses. It is shown that the model based on Euler's buckling theory as proposed by Cavers (Rock Mechanics and Rock E ngineering 1981; 14:87-104) substantially overestimates the critical height s for a vertical slope and underestimates the same for sub-vertical slopes. Copyright (C) 2001 John Wiley & Sons, Ltd.