Temperature-Dependent Model for Small-Strain Shear Modulus of Unsaturated Soils

Near-surface soils in geotechnical and geoenvironmental applications are often unsaturated, and natural or imposed changes in temperature may lead to a softening effect at constant suction that causes a change in stiffness. To capture thermal effects on the stiffness of unsaturated soils, this paper presents an effective stress-based, temperature-dependent model for the small-strain shear modulus of unsaturated soils, with an emphasis on silts. The temperature dependency of the model was accounted for by employing temperature-dependent functions for matric suction and effective saturation characterized using the soil–water retention curve. To validate the proposed model, laboratory tests using a modified triaxial apparatus with bender elements were carried out on Bonny silt to measure the small-strain shear modulus at 23°C and 43°C for varying matric suctions of 0–110 kPa. The results from the proposed model were in a reasonable agreement with the experimentally measured values and demonstrate the importance of considering temperature effects on the shear modulus of unsaturated soils. The accuracy of the model was further validated by comparing the predicted values with laboratory test results on silts reported by two independent studies in the literature.