Simulação numérica do processo de alteamento de áreas de deposição de resíduos pelo método a montante.

Abstract

The prediction of solid wastes behavior is a challenge for geotechnical engineers, since its response differ from the materials usually found in natural deposits. The analysis of the settlements of the foundation, due to the embankment raising is complex. Tailings undergo large settlements, which cannot be evaluated by ordinary consolidation theories. In Brazil, bauxite tailings are initially discharged into impoundment areas in a slurry form. After achieving the storage capacity of the reservoir, the tailing is allowed to dry, in order to enhance its resistance. Subsequently, the embankment is raised by the upstream method, and the mud is discharged on top of a material which is undergoing a consolidation process. The present research aims at reproducing numerically the response of bauxite tailings due to an upstream raising operation. The research focused 2 impoundment areas at same site. One area is being environmentally rehabilitated and is instrumented with vertical and horizontal gauges. The other is still in operation and an experimental investigation was carried out at this site. The methodology consisted of simulating the sequence of embankment raises and comparing the results with field instrumentation, in order to evaluate the numerical model and waste parameters. Subsequently, the behavior of the foundation of the area undergoing a raising embankment operation was evaluated. The geotechnical parameters were defined according to a statistical treatment of results of the experimental program (field and laboratory). The vertical and horizontal displacements, predicted by the numerical simulation, fitted reasonably well with field instrumentation and showed the inherent potential of the numerical modeling.