Experimental analysis on the cyclic strength and deformation characteristics of marine coral sand under different loading frequencies

In marine environments, cyclic loads induced by earthquakes can lead to complex soil responses in marine coral sand. Waves and storms, often at different frequencies, can also contribute to these responses. These factors can finally contribute to instability or failure of offshore structures. To better understand the effect of loading frequency on the dynamic properties of marine coral sand, a series of cyclic triaxial tests on saturated coral sands were carried out. These tests were performed with different gradations at different loading frequencies and loading modes. A GDS dynamic triaxial instrument was used for the tests. The experimental results demonstrate that loading frequency has a significant effect on the cyclic response of coral sand. The maximum shear modulus of saturated coral sand rises with increasing loading frequency. The cyclic strength of saturated coral sand also increases with loading frequency. A strong linear relationship exists between the maximum shear modulus and cyclic strength. This suggests the existence of a cyclic yield strain that is relatively insensitive to loading frequency. Loading frequency significantly affects the axial strain development of saturated coral sand under diverse loading modes. Three stages of axial strain development were identified employing incremental strain analysis. Based on these findings, a new model for axial strain development is proposed, the accuracy of this model is verified by fitting it to the data from this study and existing literature. © 2024 Elsevier Ltd