Tailings dam is in danger of liquefied instability under earthquake. The liquefaction process can be indirectly reflected by the evolution rule of the dynamic pore-water pressure. To study the dynamic pore-water evolution

a series of dynamic triaxial tests is conducted. The results show that: the development of dynamic pore-water pressure of the tailings is characterized with different stages

including an S-shaped curve under isotropic consolidation and a J-shaped curve under anisotropic consolidation. The critical pore-water pressure of tailings is close to confining pressure under isotropic consolidation. The critical pressure

less than confining pressure under anisotropic consolidation

decreases with the increase of confining pressure and consolidation stress ratio

and increases as the average particle size of tailings increases. The critical pore-water pressure equations under the condition of isotropic consolidation and anisotropic consolidation are derived based on the theory of limit equilibrium

which explain the dynamic evolution of pore-water pressure observed in dynamic triaxial tests. The results provide reference for seismic design of upstream tailings dam in earthquake area.