Graphical Methods for Slope Stability Analysis

Abstract

Introduction Nature provided most rock masses with a three-dimensional structure of more or less planar character. This geologic structure differentiates between the rock element and the rock system composed of these elements. During the last decade it has been firmly established that the geologic structure is, in many cases, of decisive importance for the stability of man-made structures supported on or placed in rock. Conventional geotechnical stability analysis generally consider the sliding of rigid bodies along existing or newly formed planes of weakness in two dimensions only. Three-dimensional problems can be solved by means of analytical geometry, however, these approaches are often too sophisticated for the stability problems encountered in engineering practice. This lecture covers the use of the hemispheric projection, generally considered to be a tool in mineralogy and structural geology, in combination with conventional engineering methods for the analysis of three-dimensional slope stability problems in jointed rock. This set of lecture notes mainly consists of excerpts of three previous papers by this lecturer supplemented by an up-to-date listing of references on this specific topic. It should be noted that the material presented in this lecture is intended to serve as first introduction to the proposed approach. For further study specific reference is made to the recent paper by Hoek, Bray and Boyd.