Variação de rigidez normal no contato rocha e solo em função do grau de saturação

Abstract

Natural disasters are increasingly common phenomena and have struck increasingly areas or regions inhabited by man. Of the various processes causing natural disasters, mass movements, specifically the rockfall type is being increasingly studied. Different factors can cause the movement of the blocks on the slope, whose range and trajectory are difficult to predict, since their behavior is governed by the geometry, by the mechanical interactions of the blocks with geological materials at the surface and by the topography of the slope. In studies of the components involved in the rockfall process, the geomechanical properties of the soil, such as stiffness can be neglected. In order to fill this gap, in this work was studied the behavior of normal stiffness in contact between rock and soil, simulating the shock that occurs on the rockfall movement, and how the humidity may come to influence the behavior of this stiffness. For it was developed a shock experiment to obtain data that are intrinsically related to the normal stiffness. Mineralogical and geomechanic characterization were also carried out for the rock and the soil used in the experiment, for the determination of parameters to be used in the calculation of stiffness. Normal stiffness, tangential stiffness and stiffness ratio were determined at different humidities, in the contacts where occurred the impacts. The results showed that there is a range of humidity in the soil, where with increasing humidity, there is an increase in the normal and tangential stiffness in the soil. This kind of behavior occurred in very low humidity, in the range of 12% to 15%. After this interval of humidities, was verified gradual reduction of normal stiffness in the soil-rock contact in function of increase of soil humidity. The ratio between the normal and tangential stiffness is around 0.90, which is an acceptable value, since it is next to the values founded in the literature scant that there is on the subject.