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The goal of this study was to improve the understanding of the soil-structure interaction mechanisms at the interface of bored concrete piles cast in sandy soils. In addition, this study aimed to quantify the interface shear strength and identify the factors that influence the response. Roughness measurements and direct shear tests were performed at the interface between two samples of sand (medium and coarse) and concrete cured under stress. The influence of the mean grain diameter, relative density, water content, concrete curing time and normal stress on the interface shear strength were statistically analyzed. The results showed a consistent behavior with the technical literature, but with higher values, which can be attributed to the concrete curing time, a factor not studied by other authors.

Large-scale mining operations generate vast quantities of tailings that are deposited in hydraulic-fill tailing dams in the form of slurries. Stability of these impoundments require investigation of water table configuration, aquifer boundaries, site characterization and determination of short and long term properties of tailings. These aspects are evaluated in this paper from a comprehensive site investigation that comprises both laboratory and field tests from a bauxite tailing deposit in northern Brazil. The purpose is to enhance the understanding on the mechanical properties of bauxite tailings in order to select or develop appropriate constitutive models for predicting the behavior of tailings impoundments. Attention is given to the characterization and classification of silt tailings from the combination of measurements from independent tests expressed on the basis of the ratio of the elastic stiffness to penetration tip resistance.