Shear strenght of the materials applied to the slope stability analysis in a humid tropical environment (São Paulo, Brasil)

Abstract

In the humid tropics, where converge intense rainy events with high temperatures, the dinamics of geomorphic systems is very intense. The superficial and subsuperficial waterflows are very active and landslides are a frequent and intense kind of processes, either in the scarps of «Serra de Caraguatatuba» and in the subsequent Paraibuna plateau. In the morphoclimatic point of view, the area of study is in the core of the «domínio dos mares de morros» of the brazilien southeast, with long, convex steep slope and deep weathering materials have been submeted to a intense throughflow in the rainy season and a surcharge represented by the forest canopy with a very superficial root system. The subject of this paper is to evaluate the thresholds of declivity for the hillslopes stability, combining a usual «limit equilibrium method» with the «infinite slope analysis». For to reach this purpose was necessary to make measures of shearing stresses: in this case with the «Cohron Sheargraph» apparatus. Another important strategy applied here was to compare the results of the shearing assays in these two contiguous, but distinct relief systems: scarps and plateau systems.