尾矿砂动力特性的动三轴试验研究

Study on the dynamic characteristics of tailings sand by dynamic triaxial test

尾矿库是堆存选矿后尾矿的场所,尾矿砂主要为细砂、粉砂等无黏性土,往往处于饱和状态,因此在地震作用下易发生液化并造成尾矿坝的失稳破坏。以某尾矿库为研究对象,通过现场勘察取样,对4种类型尾矿砂即尾中砂、尾细砂、尾粉砂和尾粉质黏土的特征进行了描述和物理参数测试。采用STX-200液压伺服式动三轴试验仪对尾矿砂试样动弹性模量、动剪切模量和阻尼比等动力学参数进行了试验测试。结果表明:试样的初始动弹性模量和初始动剪切模量均随动应变的增大先减小后趋于稳定,且受试样固结围压影响很大;随着动应变的增大,试样最大阻尼比呈明显的非线性增大,即先迅速增大后缓慢增大并趋于平稳,但其受围压的影响较小。试验结果可为尾矿库在地震作用下的动力液化分析提供数据支持。

A tailings reservoir is a site for storing tailings after mineral processing.The tailings sand mainly consists of fine sand,silt,and other non-cohesive soils,which are often saturated and thus prone to liquefaction under seismic action,leading to the instability and failure of tailings dams.Taking a specific tailings reservoir as the research object,the study conducted field surveys and sampling,and described and tested the physical parameters of 4 types of tailings sand:medium tailings sand,fine tailings sand,silt tailings sand,and silty clay tailings.Using the STX-200 hydraulic servo dynamic triaxial testing apparatus,the study performed dynamic tests on the tailings sand samples to determine their dynamic elastic modulus,dynamic shear modulus,and damping ratio.The results show that the initial dynamic elastic modulus and initial dynamic shear modulus of the samples first decrease and then stablizes with the increase of dynamic strain and are significantly affected by the confining pressure of the samples;as the dynamic shear strain increases,the damping ratio of the samples shows a clear nonlinear increase,initially rising rapidly and then increasing slowly and tending to stabilize,with little influence from confining pressure.The test results provide data support for the dynamic liquefaction analysis of tailings reservoirs under seismic action.