A new mathematical model for the estimation of shear modulus for unsaturated compacted soils

Small strain shear modulus (G) is an essential parameter for many geotechnical analyses. Most of shallow foundations are constructed in an unsaturated soil and the shear modulus of the unsaturated soil fluctuates because of the precipitation, evaporation, and rising of ground water table. In this paper, a new mathematical model is proposed for the estimation of the shear modulus function (SMF), Gunsat, which defines the relationship between small margin modulus of unsaturated soil and matric suction. In the proposed model, the soil-water characteristic curve (SWCC) in the form of the degree of saturation is used as the input information. There are additional two parameters named n and C, which can be calibrated with the experimental data, are adopted in the proposed model. The estimated results show good agreement with the experimental data from literature. The proposed method can be used to track the tendency of Gunsat and minimize the data points from the laboratory tests.