Study on the physical and mechanical properties of bauxite residue by laboratory and field in-situ tests

The determination of physical and mechanical properties of bauxite residue plays an important role on the stability assessment of tailing disposal dams. This paper studies the composition, physical properties, shear strength, and bearing capacity of bauxite residue by laboratory and field in-situ tests. The bauxite residue near the discharge point are mainly coarse particles, and the size of particle far away from the reservoir shows a decreasing trend. Through X-ray diffraction, the composition of bauxite residue is analyzed: the tailing material are mainly composed of seven main crystalline materials containing aluminum, iron, titanium, and silicon. The variation of water content with depth is measured by field tests; the water content distribution shows obvious stratification characteristic and sudden change occurs between layers. The shear vane tests show that the shear strength at a depth of more than 5 m is much larger than the material in the shallow layer close to the surface. Through dynamic penetration tests, the stratum can be categorized according to the distance from the discharge point. The bearing capacity of the soil layer close to the edge area is higher than that in the center of tailings pond. The bauxite residue shows anisotropic behavior and the mechanical property varies along horizontal and vertical directions.