The Seepage Calculation And Stability Study Of Qidashan Tailings Dam

The tailings dam is used to store tailings or other industrial waste residue from metal or non-metal mines after ore dressing.It is also a dangerous source of man-made debris flow with high potential energy.The safe operation of tailings dam is very important to ensure the safety of residents' lives and property and the green,sustainable development of mining enterprises and social stability.In this paper,Qidashan tailings dam is taken as an example.The seepage calculation and static and dynamic stability of Qidashan tailings dam are studied by FLAC3 D software,and the liquefaction of Qidashan tailings dam after dynamic response is also analyzed.The main work of the study is as follows:According to the safety technical regulations of tailings dam,the tailings dam is a secondary tailings dam,and its minimum dry beach length is 100 m.This paper studies the seepage stability of tailings dam under three different dry beach lengths by FLAC3 D.The distribution of pore pressure cloud map,the position of infiltration line and velocity vector are used to analyze the tailings dam.The results show that with the decrease of dry beach length,that is,the increase of water level,the infiltration line of dam body also rises,and the flow velocity increases gradually,and the maximum velocity occurs near the initial dam.And at 100 m dry beach length,the minimum buried depth of the infiltration line meets the requirements of 6~8m stipulated in the specification.Through the static analysis of the displacement deformation,stress distribution and shear strain of the tailings dam,the results show that the dam is in the state of compression and belongs to the stable form,and the maximum shear stress mainly occurs in the middle and lower part of the dam slope.Based on the strength reduction method,the influence of dry beach length on dam body is calculated.The results show that with the decrease of dry beach length,the shear strain region of dam body gradually increases and widens,and the shear strain region of stacked dam gradually passes through.The safety factor decreases gradually.The STAB software based on limit equilibrium method is used to evaluate its safety and the calculated results are similar to the former.Based on the study of seepage and static stability,the dynamic response analysis of tailings dam with dry beach length of 100 m is focused on under the action of dynamic load.The post-earthquake stress field,displacement field,dynamic pore pressure distribution and acceleration are studied,and the stability of tailings dam under earthquake load is evaluated by STAB software.The liquefaction analysis of tailings dam with PL-Finn model shows that large area of liquefaction occurs in the impoundment area of dam body,part of dam slope also occurs,and the pore pressure ratio is close to 0.8,and the effective stress is close to 0.Through the above research,it can be concluded that seepage stability of dam body is closely related to the length of dry beach.There is no seepage line spillover under the three working conditions,but with the increase of dam body,there is spillover risk.The minimum safety factors obtained by static analysis of dam body by strength reduction method and limit equilibrium method are 1.43 and 1.49,respectively,which meet the requirements of 1.15 stipulated in the code.However,the minimum safety factor of the dam under dynamic action is 1.16,which is close to the minimum requirement allowed by the code 1.05,and the dam has undergone large-scale liquefaction.In order to ensure the safe operation of the tailings reservoir,it is necessary to reinforce the dam body.