Dynamic behavior and deformation of calcareous sand under cyclic loading

Calcareous sand undergoes substantial cumulative deformation under cyclic loading conditions, which may affect the safety and performance of marine structures exposed to wind and waves. To investigate this phenomenon, a series of drained cyclic triaxial tests were conducted on calcareous sand under varying confining pressures (σ_c), initial deviatoric stress ratios (η_s) and cyclic dynamic stress ratios (η_d). The results reveal that cumulative axial strain in calcareous sand increases with the number of loading cycles, while the rate of increase gradually diminishes, indicating a transition to a plastic stability stage. Most of the cumulative axial strain occurs within the first 100 cycles, with minimal incremental strain in subsequent cycles. Furthermore, the stress-strain curves become progressively denser as the number of cycles loading increases. Among the influencing factors, cyclic stress ratio and initial deviatoric stress ratio have a more significant effect on cumulative axial strain compared to confining pressure. Based on the experimental data, a model for predicting the cyclic cumulative deformation of saturated calcareous sand was developed. The model's predictions closely align with the experimental results, confirming its reliability. These findings enhance the understanding of cumulative deformation behavior in calcareous sand under cyclic loading and provide valuable insights for the design and maintenance of marine infrastructure.