Foundation on Rock Mass Calculation Using Geomechanical and Finite Element Model on Western Senegal Massifs

This paper analyzed foundations behaviour on the rock mass of west cornich in the sector of Fann-Ouakam-Almady. It is done using rock mass classification, topographic data, results of laboratory test and finite element modeling. Topographic data are collected in the excavation using a total station and permit to establish the logs of this area and a three-dimensional representation of the cavity with complex lithostratigraphy of the zone. Discontinuities of the scoriaceous basanitic dolerite show that the block has no possibility of movement. This scoriaceous basanitic dolerite is of good quality while massifs composed by block of scoriaceous dolerite included in lateritic soil (altered or not) are of fair to poor quality. Rock mass parameters for foundation calculation and modeling are defined using GSI and laboratory tests. Before loading, highest displacements are located at the layer composed by block of scoriaceous dolerite in laterite and are lower than 87 micrometers. When using finite element model all facies are stable but are not stable when using rock mechanic approach. Foundations calculation shows an acceptable settlement around millimeters for all layers but displacements are more important in the layer composed by block of rock in laterite and less in basanitic dolerite. Displacement is lower when finite element method is used.