Assessment Of The Stability Of Tailings Dam And The Risk Of Dam Failure

Our country has rich miner resources,tailings reservoir accidents occur from time to time.Tailings dam break tailings discharge not only causes the waste of resources,but also causes serious impact on downstream residents,farmland,construction facilities and surrounding environment,resulting in casualty and property loss.There are many factors causing tailing dam collapse,such as flood overtopping,seismic liquefaction of dam body,and seepage failure.According to the investigation statistics,Tailings dam failure events in China and abroad are mostly caused by tailings dam seepage failure.Therefore,it is very important to study the stability of tailings dam and the risk of dam failure.In this paper,the seepage damage of the tailing dam is the core of the research,and the dynamic monitoring of remote sensing,aerial aerial aerial survey of UAV,detailed investigation in the field,indoor physical and mechanical tests,and two-dimensional and three-dimensional numerical simulation and analysis are used in this paper.A set of technical methods for evaluating the stability of tailing dam body and the risk of dam break are constructed.In this paper,the dam break process of Dagouhe tailing reservoir in Tiemen Town,Xinan County,Luoyang City,August 8,2016 is analyzed by inversion,and the effectiveness of the above method is verified.On the basis of the above research,the dam body stability and dam-break risk of Baima tailings reservoir in Huanglong Township,Miyi County,Panzhihua City,Sichuan Province,are predicted and evaluated.It provides firsthand basic data and technical support for the safe operation of the first class super large tailings reservoir.the main conclusions are as follows:(1)Through multi-stage remote sensing monitoring and field investigation,it is found that the capacity of the tailings reservoir of Dagouhe River has basically reached saturation state in front of the dam break.The tailing dam collapse is under the condition that the capacity of the tailings dam reaches saturation.Because of continuous rainfall,the soakage line of the tailings dam rises rapidly,the stability drops sharply,finally the stability collapses,and the dam-break mode is sliding avalanche type.Through the inversion analysis of the two-dimensional and three-dimensional numerical simulation,the deformation of tailings mainly occurs on the left side of the dam body near the top of the dam.the seepage line of the dam body increases with the increase of rainfall time,the deformation of the tailings dam increases,the stability of the tailing dam body decreases gradually.When the water level in the reservoir reaches 510m,the overflow will occur near the top of the dam,and the dam will slide along the left sliding surface,and finally the dam will be unstable.Through Massflow numerical simulation,After dam break,the tailings flow accumulates in the downstream movement.The total motion duration is 630s,the moving distance is 2300m,the maximum width of movement is 180m,the average thickness of accumulation is 6m,and the influence range is 3.20×10~5 square meters.The tailing sand flow moves rapidly at the initial stage and then slows down to a certain extent.The velocity of the tailing sand flow is 3.6 m/s.(2)The main risk factor of the Baima tailings reservoir is the increase of the height of the dam body,the saturation line gradually rise,and the dam body will have infiltration and destruction under the action of large reservoir pressure.Through the numerical simulation analysis,a high 180m can be accumulated on the basis of the tailings dam.In the tailings dam,each pile is increased by 10m,the overflow surface of the tailings is raised about 2m,and the deformation of tailings dam is increased by0.5~1m.With the increase of the height of the dam body,the saturation line gradually rise,infiltrates surface expands unceasingly,the deformation of dam body gradually increased,and the stability of the dam body of tailings reservoir gradually decreases.Near the top of the dam,it will give priority to the dam failure,the dam break mode is the sliding avalanche.Through Massflow numerical simulation,in extreme cases,the total sand discharge volume is 7.15×10~7 cubic meters.After the dam break,the mud sand moves downstream along the channel for 830s and ends in the Anning River.The movement path is 6km,the maximum accumulation height is 37 m,the maximum accumulation width is 600m and the accumulation range is about 2.90×10~6 square meters.The residential area A is located in the high risk area of tailings movement.The Beijing Kunming expressway is located in the middle dangerous area.The Lu Jia He Ba resettlement house and the Anning River are located in the low risk area.(3)It is more systematic and effective to use remote sensing dynamic monitoring,UAV aerial topographic survey,field detailed investigation,indoor physical and mechanical test,and two-dimensional and three-dimensional numerical simulation analysis methods to evaluate the stability of the dam body and the risk of dam break.This method can be applied to the greatest threat of seepage damage.The tailings reservoir is used to evaluate the stability of the dam body and the risk of dam break,which improves the accuracy of the evaluation work,and provides a technical reference for the stability of the tailings dam body and the risk assessment of dam break.(4)In this paper,it is considered that the infiltration line and reservoir capacity of the dam body are the most important factors affecting the tailings reservoir.With the increase of reservoir capacity and the increase of tailings gravity,the sliding force of the dam body is increased.The increase of water level in the reservoir area,the increase of water content of the tailings make the self-weight of the tailings increase,and the sliding force of the dam body increases.At the same time,the tailing sand softens after infiltration by water,and the shear strength of the saturated part decreases,so the two are coupled with each other.It causes the dam body to become unstable and slips along a sliding surface,and finally breaks the dam.In the production and operation of tailings reservoir,the height and storage capacity of the reservoir should be strictly controlled,and safety inspections should be carried out regularly to prevent accidents.