Rock mechanics investigations for rock slope stability assessment

Abstract

This paper describes investigations, geophysical and geomechanical studies of rock masses, carried out in order to analyse the stability of excavations for the Ravedis Dam and the slopes of the catchment basin upstream from the dam. A thorough geostructural survey revealed a network of discontinuities that characterizes the rock masses. Seismic tomographic investigations, analyses of data from raise borer drillings and in situ shear tests on blocks of rock were carried out in order to obtain a geomechanical picture of the density and strength of the rock masses. Geomechanical sections of the slopes were constructed by integrating geostructural, geophysical and geomechanical data; the stability of the slopes was analysed by using a slices equilibrium limit method, generally used in soil mechanics (Bell method). The computer program employed with this method was modified to take into account non-linear strength characteristics, according to the Hoek and Brown criterion, and also the possibility that failure surfaces may develop along natural discontinuities. Reinforcement of the rock mass with an artificial increment in cohesion was simulated using the concept of “reinforced rock”.