饱和层状尾砂动力特性研究*

为探究动力作用下尾砂液化破坏特性，基于某矿山尾矿库坝体分层尾砂，开展不同固结应力和层状结构条件下动三轴试验，分析层状尾砂动弹性模量、阻尼比及动剪应力比等动力参数与动孔压的变化规律。结果表明:固结应力对层状尾砂力学特性和动孔压变化趋势有较大影响，固结应力越大，动孔压增长越明显，初始增长斜率随固结应力增大而下降；尾粉土厚度一定时，固结应力越大，层状尾砂动剪应力比越小；固结应力为常数时，层状尾砂动剪应力比随尾粉土厚度增加先增大后减小，当尾粉土厚度为0，20，40，80 mm时，对应动剪应力比分别为0.33，0.35，0.38，0.28；尾粉土对孔隙水压力阻隔作用比尾细砂更明显，试样破坏所需振次随尾粉土厚度增加而增加。研究结果可为高烈度地震区尾矿坝地震液化研究提供理论参考。

Research on dynamic characteristics of saturated layered tailings

In order to explore the liquefaction and failure characteristics of tailings under the dynamic effect,based on the apparently layered tailings of dam body in a mine tailings pond,the dynamic triaxial tests under different consolidation stresses and layered structure conditions were carried out to analyze the change laws of the dynamic parameters such as dynamic elastic modulus,damping ratio and dynamic shear stress ratio of layered tailings and the dynamic pore pressure.The results showed that the consolidation stress had greater impact on the change trends of the mechanical characteristics of layered tailings and the dynamic pore pressure,the greater the consolidation stress,the more obvious the increase trend of dynamic pore pressure,and the initial increase slope decreased with the increase of consolidation stress.When the thickness of tailings silt was constant,the greater the consolidation stress,the smaller the dynamic shear stress ratio of layered tailings.When the consolidation stress was constant,the dynamic shear stress ratio of layered tailings increased first and then decreased as the thickness of tailings silt increased,and when the thickness of tailings silt was 0,20,40 and 80 mm,the corresponding dynamic shear stress ratio was 0.33,0.35,0.38 and 0.28,respectively.The tailings silt had a more obvious blocking effect on the pore water pressure than the tailings fine sand,and the number of vibrations required for the failure of sample increased with the increase of the thickness of tailings silt.The research results can provide a reference for the seismic liquefaction of tailings dams in the high intensity seismic areas.