Experimental study on the liquefaction resistance and dynamic deformation characteristics of tailings in earthquake-prone areas

To investigate the liquefaction resistance and dynamic deformation characteristics of tailings in earthquake-prone areas, this study focused on samples from an upstream tailing pond. Initially, it examined how sedimentation and consolidation behaviors are affected by the fine content (FC) of the tailings. Subsequently, dynamic triaxial tests were conducted to assess the impact of FC on the liquefaction resistance and dynamic deformation characteristics. Furthermore, this study analyzed the impact of FC on the dynamic deformation characteristics of tailings considering their microstructural features. The results revealed distinct consolidation processes at different depths in the tailing pond; leaching and chemical consolidation predominate in the upper layers, while self-weight consolidation is more common in the lower layers, with the FC increasing nonlinearly with depth. The dynamic shear stress, when plotted on a logarithmic scale, decreased approximately linearly as the number of dynamic cycles increased. An increase in effective consolidation confining pressure enhances particle contact, requiring stronger dynamic loads to destroy the tailing structure. The liquefaction resistance of the tailings first decreases and then increases with rising FC levels. A lower FC resulted in a higher liquefaction resistance and a quicker attenuation of the cyclic stress ratio in the tailings, whereas the FC variations weakly affected the dynamic pore water pressure ratios. The relationship between the dynamic pore water pressure ratio and vibration ratio follows a three-stage pattern: decelerating, stable, and accelerating growth. A larger consolidation pressure can partially suppress the dynamic pore water pressure growth to a certain extent. In addition, a two-parameter simplified model for dynamic pore water pressure, tailored to the tailing characteristics, was derived from a more complex three-parameter model. Moreover, the dynamic shear modulus of the tailings initially decreased and then increased with FC, whereas the damping ratio initially increased and then decreased. The dynamic deformation characteristics of the tailings gradually shift from being controlled by coarse particles to fine control, with a critical FC value observed during this process. Before and after reaching this critical FC, the dynamic shear modulus and damping ratio of the tailings exhibit opposite trends in relation to FC. However, further detailed dynamic triaxial testing across different FC ratios is necessary to determine the precise value of the critical FC value for the tailings. These results provide a theoretical foundation for assessing the stability of tailing ponds and analyzing tailing dynamics in earthquake-prone areas.