Interaction between geological and geotechnical investigations of a sandstone residual soil

This paper discusses results of geological and geotechnical investigations carried out on a residual soil originated from the weathering of a southern Brazil sandstone, the Botucatu formation. Triaxial compression tests with local strain measurement were used for the evaluating stiffness and strength parameters of this soil. Its microstructure was investigated using both optical and scanning electron microscopy. Important differences observed in relation to the expected geomechanical behaviour of structured soils are explained by considering details of soil fabric shown by these microscopy analyses.