MECHANICAL INVESTIGATION OF AN ANOMALOUS CLAYEY SAND SOIL USED AS LANDFILL COVER LAYER

Resumo

Given the increase in the purchasing power of population, there is an increment in waste
generation. Considering it and the scarcity of adequate areas for final disposal of municipal solid
waste, it is recurrent that landfills’ managers invest in increasing the load capacity of landfills. Then,
landfills are work of high geotechnical risk in terms of slope stability. Thus, it is important to
investigate the mechanical behavior and stability of landfill’s slopes. It should also be noted that the
deposits of soil, when mined for raw material supply to compose landfill cover layers, become less
stable representing risks to local workers. Therefore, it is important to verify the stability of soil
deposits too. In this sense, this paper proposes a geomechanical investigation on the landfill slope
stability, as well as on the soil deposits’ slope. Experimental and numerical analyzes were performed.
Experimental ones consist of soil’s grain size characterization, soil compaction, and direct shear tests
in natural condition, from which the needed parameters to proceed with numerical analyzes were
obtained. Numerical analyzes integrate two modeling developed by a software applying the limit
equilibrium method improved by Morgenstern & Price. The soil was classified as a clayey sand; it
presented an expected friction angle (34.8o) for a sandy soil, but cohesion (56.6 kPa) was above the
expected for a soil with 69% of sand. From numerical modeling, it was observed that the soil deposit
is stable with FS = 3.1, as well as the landfill cell, which presented FS = 2.2.