Comportamento morfodinâmico de uma vertente com latossolo em Venda Nova do Imigrante-ES

Abstract

This dissertation associates the morphodynamic processes current to the mechanical behavior of a residual Oxisol of gneiss, a policonvexa slope located in São João de Viçosa, district of municipality Venda Nova do Imigrante - ES. Considering the incidence of mass movements, the literature classifies Oxisol like stable. However, in the study area were ascertained evidence slip translational. The investigation into the causes of this event was based on geomorphological analysis and in the interpretation of test results aimed at soil mechanics. To understand the dynamic of the surface flow and its relationship with material movement the slope, it was generated a cartographic product which corresponds to the geomorphology of the area partitioning. This in turn, supported the proposal the analysis integrated of relief methodologically grounded this research. From the investigation of three different levels of approach, Compartmentalization Topographic, Surface Structure of Landscape and Landscape Physiology, tried to establish relations of cause and effect that pluviometric events, water behavior in soil and human activities exert on the study area, which allowed evaluating the stability of the slope. The magnitudefrequency rainfall events indicated that rainfall of 17, 21 mm are the most frequent in the study area during the year and prepare the soil for water ingress. To understand the hydro-mechanical behavior of the soil the following tests were performed: characterization of soil (Atterberg limits, actual density of the grains, organic matter content), physical analyzes of particle size, porosity, macroporosity and microporosity, hydraulic conductivity, water dispersed clay, soil bulk density and direct shear test. The water retention curve in the soil reflected a clay soil behavior to the depths sampled the BW1 horizon investigated and the integration of the results allowed establishing a hydraulic discontinuity 1.5m deep in this horizon. The results also indicated that the texture, structure and porosity of the sampled Oxisol influence largely in shear strength. By means of direct shear testing were obtained the angle of friction values for cohesion and BW1 horizons 27,69º; 0,12kgf/cm2 and C 32,82º and 0.05 kgf/cm2 and these in turn were used as parameters in the stability analysis Slope/W ™ software. It was concluded, therefore, that changes in the natural dynamics of the slope due to the use and opening cuts to expand routes and occupation, are directly related to the instability of the ground.