Abstract: The accumulation of the excess pore water pressure of saturated sand under various cyclic loadings is the cause of soil liquefaction, and it is a relatively new research idea to treat the liquefiable sand as a fluid. A comprehensive experimental investigation of the liquefaction flow characteristics is performed for the saturated coral sand subjected to the jump of 90° and the continuous rotation of the principal stresses with cyclic loading frequency (f) at isotropic consolidations. The test results show that the relationship between the normalized apparent viscosity (η/η₀) and the excess pore water pressure ratio (r_u) is significantly affected by the cyclic stress paths, the degradation of η/η₀ with r_u is a progressive process, and a positive exponential correlation exists between the average flow coefficient (\bar \kappa ) and r_u. The correlations between η/η₀ and r_u and between \bar \kappa and r_u seem to be independent on the cyclic stress ratio (CSR = 0.25~0.40) and f (= 0.1~1 Hz). Another significant finding is that the apparent viscosity gradient and the average flow coefficient gradient both increase first and then decrease with the increase of r_u regardless of the jump of 90° and the continuous rotation of the principal stresses, and r_u approximately equal to 0.9 at the reversal point can be regarded as the threshold value of the excess pore water pressure ratio (r_uth) at the phase transformation state from the solid state to the liquid one, by denoting the corresponding \bar \kappa as \bar \kappa _\textth. The data points of \bar \kappa /\bar \kappa _\textth-r_u for all testing conditions are distributed in a narrow band, and a virtually positive exponential relationship exists between \bar \kappa /\bar \kappa _\textth and r_u.