Study On The Stability Of Red Mud Tailings Yard And The Optimal Stacking Method

Tailings pond is a hydraulic structure used to store tailings or waste residue.Chi-ni-tail mine yard is a tailings pond formed from industrial wastes accumulated in the project of producing alumina.Red mud is characterized by strong alkali,weak corrosion,high water content,weak permeability,large porosity,low strength and soft variability.Therefore,reducing the wetted surface of the red mud storage yard is one of the important indicators to maintain the stability of the storage yard during the wet discharge of the red mud.During the dry drainage of red mud,the external water in the storage shall be discharged out of the storage in time to reduce the influence of water on the stability of the storage yard.This paper takes a red mud tailings yard in Shanxi as an example to analyze the static and dynamic stability of the red mud tailings yard,and the main conclusions are as follows:(1)Taking a red mud tailings yard in Shanxi as the research object,a series of test data were obtained through seepage test,static triaxial test and dynamic triaxial test,which provided the basis for subsequent numerical simulation.(2)The current accumulation mode is wet drainage.The three-dimensional seepage field analysis of the current dam height shows that the shallowest buried depth of the wetted surface of the storage yard is 7 m.Due to the poor permeability of red mud,the seepage velocity in the storage yard is slow and the safety reserve is insufficient.(3)The Duncan-Zhang E-V model is used to conduct nonlinear static analysis on the status quo,the Donggou and the final storage site respectively,and the distribution of the maximum and minimum principal stresses is obtained,thus providing a basis for judging the stability of the red mud tailings storage site;The main deformation of the depot is vertical deformation,and the vertical deformation of the present condition,the east ditch and the final depot are 0.15 m,0.21 m and 0.22 m respectively.(4)Using the Moors-Coulomb stress-strain relationship,the strength reduction method is adopted to analyze the slope stability of the current situation,the east ditch and the final storage site,and the minimum safety factors of the current situation,the east ditch and the final storage site are 2.20,2.20 and 2.00 respectively.The plastic deformation zone of the storage yard is obtained.(5)By using the equivalent viscoelastic stress-strain relationship,dynamic analysis under the Elcentro seismic wave and artificial seismic wave was carried out on the current situation,the east ditch and the final storage site respectively to obtain the distribution of liquefied zone under the current wet discharge condition.Time history analysis was used to analyze the dynamic response of the storage yard.The maximum amplification coefficients of the horizontal direction of the current situation,the east ditch and the final storage yard were 5.51,5.37 and 5.43 respectively,and the maximum amplification coefficients of the vertical direction were 3.54,4.03 and 3.61 respectively.The softening modulus method is used to analyze the permanent deformation of the depot.The vertical deformation is the main deformation of the depot.The vertical permanent deformation of the current condition,the east ditch and the final depot are 0.53 m,0.55 m and 0.58 m,respectively.Time history analysis method is used to analyze the safety factor of the storage yard,and the safety factor of each time point of the current situation,the east ditch and the final storage yard is obtained.The minimum safety factor of the current situation,the east ditch and the final storage yard are 1.07,1.10 and 1.10 respectively,which meet the safety requirements.From the above analysis,it can be concluded that the safety reserve of the storage yard is small under the condition of current wet discharge,and there are safety risks.After the stacking mode of the storage yard is improved to dry drainage,the stability of the storage yard is improved.The final dry drainage red mud tailings storage yard is stable in the area with seismic intensity of ? degree.