SOIL-WATER CHARACTERISTIC CURVE OF UNSATURATED SILTY CLAY SOIL AND ITS USE TO PREDICT THE SOIL STRENGTH

The Global Digital Systems Ltd. (GDS) unsaturated soil triaxial test system is used to determine the shear strength of unsaturated undisturbed silty clay soil and obtain the soil-water characteristic curve. The van Genuchten (VG) and Gardner (GD) models are used to fit the soil-water characteristic curve to predict and verify the shear strength of the soil. The results show a better fit for the GD than the VG model. The shear strength of the soil increases with an increase in the matric suction, but the rate of increase is relatively low. The most significant influence of the matric suction on the soil strength is observed at less than 150 kPa. The influence of the matric suction on the shear strength of unsaturated silty clay mainly depends on the total cohesion. The soil shear strength value predicted by the GD model is conservative, but the predicted value tends to approach the measured value with an increase in the matric suction.