262 / 2018-03-14 14:55:16

Experimental Study on Effect of Matric Suction on Shear Strength of Unsaturated Tailings Dam Material

matric suction; tailings dam; shear strength; SWCC; cohesive force

矿山安全科学理论与应急救援 > 矿山安全科学理论

In view of the stability of the unsaturated tailings dam, filter paper method was used to determine the matric suction of the water content for tailings in the dam in 2.23%~43.87%. Soil water characteristic curve is set up then. Cohesive, internal friction angle and its shear strength under the corresponding water content were obtained by the direct shear test. And the results of the test are calculated and compared. Shear strength of the tailings dam and the variation of its parameters with the matric suction are discussed. The results show that the matric suction has a significant influence on the shear strength and its parameters. Shear strength with the matric suction process can be divided into four sections, showing the characteristics of the first increase and then decrease and then tends to be stable. When the matric suction is about 486kPa, the shear strength under the four positive pressure reaches the maximum. This is 46.7% ~ 105.3% higher than the saturated state. The moisture content close to the sample plastic limit (16.1%). Variation of matric suction with dry density varies with water content, and is sensitive to dry density only when water content is less than 26.9%. The change of cohesive is basically the same as that of shear strength. However, at each stage the degree of change is greater than that of the shear strength, and the sensitivity of the matric suction is stronger, and it is approximately consistent with the distribution of the Gauss function. Internal friction angle agrees with the Sigmoidal function with the change of moisture content. With the increase of matric suction, it shows a monotonically increasing feature, which is not consistent with the shear strength. Shear strength part of the matric suction can be considered as a part of the "apparent cohesive force". Matric suction mainly influences the shear strength of the tailings dam by influencing the cohesive force.