Mechanical Characteristics of Tailings in Different Depositional Zones: A Case Study of Caijiagou Tailings Pond in Shaanxi, China

This study examines the widespread practice of upstream tailings dam construction in metallurgical mines in China, conducting comprehensive testing and research on tailings from various depositional zones of the Caijiagou tailings pond. Analysis of the test results from three types of tailings reveals a systematic relationship between the mechanical characteristics of tailings and their depositional zones: the farther from the dam, the finer the tailings particles, categorized as silty clay tailing, silt tailing, and sandy silt tailing. Consistent patterns were observed in the consolidated-drained shear strength and consolidated-undrained effective shear strength of these tailings. Among these, sandy silt tailing exhibited the highest strength, whereas silty clay tailing displayed the lowest. The dynamic stress–strain relationships of all three tailings types are described using the Hardin equivalent viscous-elastic model, where the initial dynamic shear modulus and the maximum dynamic shear stress in the model increased with effective confining pressure. The damping ratios exhibited a three-stage trend with increasing dynamic strain: gradual increase, rapid growth, and then gradual stabilization. Under various consolidated stress conditions, the ratio of the damping ratio to the maximum damping ratio versus the reduction in dynamic shear modulus showed a favorable linear relationship. Under vibration conditions, the dynamic shear stress corresponding to tailings failure increased with higher effective confining pressure and consolidated stress ratio. Finally, this study summarizes the parameters and indicators related to the saturated tailings of iron mines used in the research. Our work provides a foundation and reference for the design of tailings dams and the development and utilization of abandoned tailings ponds.