Prediction model for generation trend of axial deformation of saturated coral sand under cyclic loading

The complex deformation of saturated anisotropic coral sand under cyclic loading is investigated in undrained cyclic triaxial tests. From the results, the interplay between consolidation ratio (kc) and cyclic stress ratio (CSR) greatly affects the evolution of axial strain in coral sand, categorized as residual and fluctuating via inherent and stress-induced anisotropy. Correspondingly, two axial strain generation modes are observed in saturated coral sand: cyclic mobility and cumulative plastic deformation. For isotropic consolidation, the residual strain of loose coral sand increases by 19.5 % as CSR increases by 0.1, indicating the influence of inherent anisotropy on deformation. With decreasing CSR and increasing kc, the mode shifts from cyclic mobility to cumulative plastic deformation. For anisotropic consolidation with kc = 2.0, the cumulative plastic strain exceeds 95 % for loose coral sand. A novel empirical model is proposed to predict the progression of both residual and fluctuating axial strain in saturated coral sand, and compared with experimental data, the prediction error for both peak and valley axial strain is within 10 %.