Investigation of the Effect of Relative Density on the Dynamic Modulus and Damping Ratio for Coarse Grained Soil

As the critical dynamic parameters for soil, an extensive examination of the dynamic elastic modulus Ed and damping ratio λ in coarse-grained soil is of significant theoretical and practical importance. Currently, there is a scarcity of experimental equipment and methods for measuring the dynamic elastic modulus and damping ratio of coarse-grained soils. Moreover, studies examining the influence of relative density on these parameters in coarse-grained soils are largely absent. To investigate the behavior of the dynamic elastic modulus and damping ratio in coarse-grained soil under varying relative densities, a number of dynamic triaxial tests were conducted on a specific coarse-grained soil using the DYNTTS type dynamic triaxial test apparatus. The findings reveal that, under various gradations, the Ed of coarse-grained soils exhibits a decreasing trend with increasing dynamic strain, a trend that intensifies with higher relative densities. Additionally, as relative density increases, the degradation rate of the dynamic shear modulus ratio Gd/Gdmax to dynamic shear strain γd curve escalates. The maximum dynamic shear modulus Gdmax rises with increasing relative density Dr, displaying a linear relationship between Gdmax and Dr. Furthermore, both the increasing rate of λ to γd curve and the maximum damping ratio λmax progressively diminish with the escalation of relative density Dr. Notably, the maximum damping ratio has a power function relationship with the relative density.