| The dam break of the tailings reservoir will not only lead to the destruction of the ecological environment,but also seriously threaten the life and property safety of the downstream masses.In 2008,Shanxi New Tower Mining Co.,Ltd.tailings warehouse collapse Dam,leaking tailings about 190,000 m~3,submerged area of 35hectares,resulting in 277 people killed,33 injured,direct economic loss of 96.19million yuan.In 2019,34 people were killed,23 injured,250 were missing and the sediment deposition reached 10m deep in a dam break at an iron ore mine in Minas Gerais,Estado De,Brazil.Therefore,it is very meaningful to study the development form of broken mouth and the evolution range of sediment and water flow in the downstream after the collapse of the tailings reservoir.Numerical simulation method is used to calculate and analyze the influence range of dam break in tailings reservoir,which has become one of the reliable methods at present.Taking an actual tailings reservoir as an example,this paper simulates the dynamic process of the gradual dam break of the tailings reservoir based on numerical simulation,and mainly carries out the following aspects of research:(1)Collecting the data of tailings dam collapse in the United States,Europe and China,and analyzing the influence of dam height and tailings dam damming method on dam break of tailings reservoir.(2)In order to verify the correctness of the selected model,taking the experiment of dam break in the literature model as an example,a three-dimensional numerical model of the gradual dam break in the sink is established based on FLOW-3D,and the development form and water depth change of the non-viscous earth dam with initial notch are compared with the experiment.(3)According to the topographic map of an actual tailings reservoir,t three-dimensional numerical models of two working conditions were established by civil 3D Software and AUTOCAD software respectively.Based on the numerical model,the calculation of the gradual dam break of the tailings reservoir is carried out in the FLOW-3D software,and the calculation results are imported into the post-processing software Flowsight for processing and analysis.(4)Analyzing the shape change,flood evolution process,whole tailings sedimentation range and flow velocity field of the tailings reservoir in the gradual collapse of the dam.And studying the variation law of water level in typical monitoring points near downstream villages and houses.(5)According to the calculation results,the influence degree of tailings dam outburst flood on village and house inundation is evaluated,and some feasible engineering measures are put forward.(6)In order to reduce the influence degree of dam break sand flow on the downstream area,the engineering measures of setting up blocking dam in the lower reaches of tailings dam are taken,comparing the calculated results with the failure to take engineering measures,and analyzing whether it is feasible to take engineering measures.The results of the study show that:(1)According to the statistics at home and abroad,it can be seen that the stability failure is the most important cause of the dam collapse of the tailings reservoir;more than 70%of tailings dam breaks dam height less than 30m;and the upstream dam method is more prone to dam break.(2)For the verification model in the water tank,the calculation results show that the morphological change of the notch in numerical calculation is consistent with the experimental results,the change trend of upstream and downstream water level is the same,so the applicability and accuracy of the numerical simulation are verified.(3)The calculation data of water flow and tailings evolution show that:After the collapse of the tailings reservoir,the flood of dam break evolves downstream,the amount of water decreases gradually,and the sediment is silted along the course until it is stable.In the working condition one,the maximum flow rate of a section is2120.54m~3/s,and the maximum water depth of the monitoring point is 15.44m.The total amount of tailings discharge about 421,000 m~3,accounting for about 31.1%of the total tailings.In the working condition two,the maximum flow rate of the section1448.99m~3/s the maximum water depth of 10.10m.The total amount of tailings discharge about 347,000 m~3,accounting for about 41.6%of the total tailings.(4)Dynamic calculation data of tailings dam rout show that:the water flow first rushes down along the initial breach when the tailings dam breaks,and then gradually erodes to both sides.As the break continues to expand,the water flow and flow rate at the break is increasing,while increasing the scour on the bottom and sides of the notch,resulting in more and more serious erosion.In the end,the erosion section of dam body showed U-type distribution.(5)After taking the engineering measures,the blocking dam blocks most of the sediment,effectively slows down the evolution of water flow and sediment,and the cross-sectional flow rate is obviously reduced;However,the water depth of the downstream housing monitoring point 4-6 is more than 5m,so the adoption of engineering measures has little impact on the residents of the downstream villages. |
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