Strength and Deformation Characteristics of Unsaturated Fine-Grained Tailings Soil Under Variable Moisture Content

Abstract

Previous research has not analysed the strength and deformation of unsaturated fine-grained tailings soil under variable moisture content. This paper discusses individual tests for the compressibility, direct shear strength and triaxial strength of fine-grained tailings soil, under those variable moisture content. The experimental results showed that: (1) With an increase in specimen moisture content, resistance to vertical deformation gradually declined and reached a minimum at saturation; (2) The cohesion of unsaturated fine-grained tailings soil tended to decrease with an increase of moisture content, and had an obvious peak. The angle of internal friction decreased as moisture content increased, exhibiting an approximately inverse linear relationship; (3) Moisture content exhibited a very obvious effect on the stress and strain characteristics of unsaturated fine-grained tailings soil. Under the same confining pressure, as moisture content increased, the axial stress which was applied on the specimen declined, and its ultimate strength was also reduced. As moisture content declined, the specimen damage type changed from strain hardening to strain softening. With an increase of moisture content, the volumetric strain of the specimens initially increased then decreased. Presumably, the volumetric strain should peak when the moisture content reaches an optimum level.