Abstract: The soil-water retention curve is the basis for the study of the strength, deformation and seepage characteristics of unsaturated soils, but the direct measurement of the curve in laboratory is complicated and time-consuming. In order to quickly and accurately obtain the soil-water retention curve of granite residual soil, the resonant column tests were carried out on granite residual soil with different water contents, the small-strain shear modulus characteristics of unsaturated granite residual soil were also studied. The soil-water retention curve of granite residual soil was inverted on the basis of the double-stress-variable maximum shear modulus prediction model and the single-stress-variable maximum shear modulus prediction model for unsaturated soils, respectively. The results show that the water content has a significant effect on the small-strain shear modulus of granite residual soil, and the shear modulus decreases with the increase of water content and increases with the increase of confining pressure. The inversion result of the soil-water retention curve based on the double-stress-variable maximum shear modulus prediction model is more consistent with the pressure plate experimental data. The accuracy of this prediction model is verified by the experimental data, and its mechanical mechanism is discussed. The resonant column test can not only directly study the small-strain shear modulus characteristics of unsaturated granite residual soil, but also project the soil-water retention curve of granite residual soil by the inversion method, which provides a new method for obtaining the soil-water retention curve.

Key words: undisturbed granite residual soils, resonant column test, small-strain shear modulus, unsaturated soil, soil-water retention curve, inverse analysis