Modelagem da resistência ao cisalhamento de resíduos sólidos urbanos para análises da estabilidade de taludes de aterros sanitários.

Abstract

Slope failures in landfills are attributed to heterogeneous composition, inadequate shear strength parameters assessment, biodegradation effects in the Municipal Solid Waste (MSW) resistance, and the gap of understanding material variability over time. In order to minimize the risk of slope failure, it is necessary to accurately estimate the shear strength parameters, as well as other parameters, such as specific weight, water content and composition, which affect the stability of slopes in landfills. This work aims to develop shear strength models to analyze the stability of landfill slopes. This work was developed at the Sanitary Landfill located in Campina Grande-PB. Samples of waste landfilled 0.1 and 2 years ago were collected and characterized. The landfill was instrumented to monitor vertical and horizontal displacements, piezometric levels and liquid flow. The meteorological conditions of the landfill were also monitored. With this information, constitutive and non-constitutive models were developed to determine the waste's shear strength and analyze the slope stability of the Sanitary Landfill in Campina Grande. The results of gravimetric characterization indicate that the fraction of mixed material represents the highest percentage at every stage in time and this fraction increases as the waste ages. The physical-chemical characterization of the waste reveals that the biodegradative process at the Sanitary Landfill in Campina Grande rapidly occurs, presenting characteristics of a landfill over the age of 5 years in the first year of operation. The shear stress increases with increasing waste age, normal stress and horizontal displacements. The ASCG has high liquid levels and low vertical and horizontal deformation. The constitutive and non-constitutive models are a good fit for the experimental data and can predict the shear stress, cohesion intercept, and friction angle of MSW at various ages, moistures, and specific weights under saturated or unsaturated conditions. Through the developed models, it was possible to verify that the slopes of the ASCG are stable with a factor greater than 1.5. The application of the models allowed the analysis of slope stability and proved to be a viable tool to determine or predict the resistance parameters of grounded MSW.