Abstract:The effect of P-wave (longitudinal wave) on soil under strong earthquake motions cannot be ignored. However, the traditional method of analyzing the dynamic behavior of soil under cyclic loading by unidirectional vibration often ignores the influence of P-wave on the dynamic stability of the soil. To study the dynamic characteristics of tailing sands under high stress, a series of bidirectional vibration triaxial tests under different confining pressures, dynamic shear stress ratios, and consolidation stress ratios were carried out adopting bidirectional cyclic loads to simulate seismic loads. The result showed that under bidirectionally excited cyclic loading, the saturated tailing sands had a cumulative plastic deformation ε_tp when isobaric consolidation and anisotropic consolidation. With the increase of dynamic stress amplitude, ε_tp had a linear negative correlation with the vibration’s times during isobaric consolidation, and a linear positive correlation with the vibration’s times during anisotropic consolidation; the cumulative pore-pressure curves of tailing sands were characteristic of stages. Confining pressure had a significant effect on the characteristic of the cumulative pore-pressure curves of tailing sands. When the confining pressure was the same, changes in the dynamic shear stress ratio and consolidation stress ratio had little effect on the characteristic of the cumulative pore-pressure curves. With the increase of confining pressure, the cumulative pore-pressure curves of tailing sands under isobaric consolidation and anisotropic consolidation had two development modes of 3 or 4 development stages. When the cumulative pore-pressure curves had three stages, the characteristic of the cumulative pore-pressure curves of tailing sands under isobaric consolidation and anisotropic consolidation had a significant difference. However, when the cumulative pore-pressure curves had four stages, the characteristics of the cumulative pore-pressure curves of tailing sands under isobaric consolidation and anisotropic consolidation were the same. Besides, through the analysis of the test results, the cumulative pore-pressure growth model of tailing sands under high-stress considering multiple factors was derived, and two forms of this model were obtained under isobaric consolidation and anisotropic consolidation. Thus, the research findings can provide a reference for the seismic reinforcement design of the tailings dam.