不同固结条件下尾矿动孔压演化规律

Dynamic pore-water pressure evolution of tailings under different consolidation conditions

地震作用下尾矿坝有液化失稳的危险,尾矿动孔压的演化规律可以间接体现其液化过程。为研究尾矿动孔压的演化规律,开展了一系列的动三轴试验。结果表明:尾矿动孔压演化具有明显的阶段性,在等压固结时可用S形反正弦函数曲线描述,在偏压固结时可用J形指数函数曲线描述;尾矿材料在等压固结条件下临界孔压接近于围压,在偏压固结条件下临界孔压小于围压,且随围压及固结应力比的增大而减小,随尾矿平均粒径的增大而增大。基于极限平衡理论推导了等压固结和偏压固结条件下的临界孔隙水压力方程,从理论上阐释了试验结果所揭示的动孔压演化规律,可以为地震区上游式尾矿坝的抗震设计提供参考。

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.