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.