Abstract: At present, the commonly used methods to determine the dynamic shear modulus of soil include the standard method, the Kumar method and the autocorrelation function method. The methods to determine the corresponding damping ratio include the standard method, the Das and Luo method, the Kokusho method, the Kumar method, and the cross-correlation function method. So far, the understanding of the differences caused by the different methods is not deep enough, and there is a lack of quantitative comparative analysis. In this study, the Fujian standard sand (particle size 0.5-1.0 mm) was used as the research object, and the undrained stress-controlled dynamic triaxial test was used to discuss the differences of the different methods so as to determine the dynamic shear modulus and damping ratio of the sand, and then to recommend the method to use. The results show that:1) The dynamic shear modulus determined by the three methods has a certain difference. The difference gradually increases with the increase of the shear strain, but the difference decreases with the increase of the effective confining pressure. When the shear strain is 4×10^-3 and the effective confining pressure is 100 kPa, the difference between the three methods is the most significant, and the maximum relative error is close to 20%. 2) The damping ratios of the five methods have significant differences. The relative errors of the five methods for determining the damping ratio decrease rapidly with the increase of the shear strain; When the effective confining pressure is 100 kPa, the damping ratio only by the standard method has a smaller increasing trend. Among them, the damping ratio determined by the Kumar method is closest to the average damping ratio, the damping ratio by the cross-correlation function method is much higher than the average damping ratio, and the damping ratio determined by the Das and Luo method and the Kokusho method is basically the same but lower than the average damping ratio. So, it is recommended that in future engineering applications, when the loading method is stress control, the correlation function method can be used to determine the dynamic shear modulus and the Kumar method to determine the damping ratio.

Key words: standard method, Kumar method, autocorrelation function method, Das and Luo method, Kokusho method, cross-correlation function method, dynamic shear modulus, damping ratio, sand