THE RELATIONSHIP OF THE UNSATURATED SOIL SHEAR-STRENGTH TO THE SOIL-WATER CHARACTERISTIC CURVE

The measurement of soil parameters, such as the permeability and shear strength functions, used to describe unsaturated soil behaviour can b e expensive, difficult, and often impractical to obtain. This paper pr oposes a model for predicting the shear strength (versus matric suctio n) function of unsaturated soils. The prediction model uses the soil-w ater characteristic curve and the shear strength parameters of the sat urated soil (i.e., effective cohesion and effective angle of internal friction). Once a reasonable estimate of the soil-water characteristic curve is obtained, satisfactory predictions of the shear strength fun ction can be made for the unsaturated soil. Closed-form solutions for the shear strength function of unsaturated soils are obtained for case s where a simple soil-water characteristic equation is used in the Pre diction model.