AN ENERGY-BASED MODEL FOR GENERATION OF EXCESS PORE WATER PRESSURE IN SATURATED CORAL SAND UNDER ANISOTROPIC CONSOLIDATION

A series of undrained cyclic shear tests were carried out on saturated coral sands with different initial physical states, as they were subjected to rotations of 90° in the paths of cyclic stress under various consolidation conditions. An important finding from the test results is that both soil properties (fines content FC and initial relative density D_r) and consolidation conditions (consolidation confining pressure p'_0, the consolidation inclination α_c and the consolidation ratio k_c) significantly affect the relationship between u_e and W, and are less affected by cyclic loading conditions (cyclic loading frequency, cyclic stress path and cyclic stress ratio). When FC is less than the threshold fines content, the cumulative dissipated energy required for liquefaction (W_s) increases with the increase of FC and decreases with the increase of D_r. Under isotropic consolidation conditions, W_s increases significantly with the increase of p'_0. For the anisotropically consolidated specimens, the stable value of u_e first increases and then decreases with the increase of α_c, and decreases with the increase of k_c. The equivalent intergranular void ratio (e_\textsk^ * ) was introduced to reflect the effects of FC, physical states of the particles and inter-particle contact on physical properties of coral sand. The relationship between the excess pore water pressure ratio (r_u) and the normalized cumulative dissipation energy (W_R) of saturated coral sand under isotropic consolidation conditions is unique. The empirical parameters considering α_c and k_c are put forward, and the arctangent function model of modified r_u increasing with W_R is established for saturated coral sand with different physical states and complex stress conditions.