Stability Analysis And Dam Break Simulation Of Niuchangping Tailings Pond

Under the international situation,the demand of mineral resources as a strategic resource is increasing rapidly.With the continuous increase of mining,the volume of tailings produced after selection is also increasing,the tailings are usually stored in a tailings pond.However,tailings dam accidents often occur in the world,and the failure of tailings dam is the most common.A large number of facts have proved that it is easy to cause serious accidents when the risk of dam-break occurs in the tailing pond,and its operation is not only directly related to the safety of mine production,it also affects the safety of life,property and social stability of the residents near the tailing pond.Although some progress has been made in the research and treatment of tailings pond in recent years,most of the studies are focused on the single-dimensional analysis of tailings pond,the stability analysis is usually carried out by single method without considering both two-dimensional and three-dimensional stability results,which can not reflect the actual operation of the tailing pond.In view of the above-mentioned phenomena,this paper chooses Niuchangping tailing pond in the Eastern District of Panzhihua province as the research object,combined with the numerical simulation,the stability of the tailing pond is analyzed under the three-dimensional state and the generalized two-dimensional state,and the results of the two analyses are compared,the severity of dam failure of tailings reservoir was evaluated.The main research contents and results are as follows:(1)According to the flood prevention and drainage calculation of the Niuchangping tailings pond,the peak flow rate Qp of the tailings pond is 162.081m3/s.The total flood volume Wp is1.15165 million m~3;Through the flood hydrograph,it can be obtained that the rainstorm duration t=1.016h,and the flood flow reaches the peak Qp;According to the flood regulation calculation,the maximum discharge of the tailings pond at 6.602h is 32.274m3/s.The required flood control storage capacity is 565460 m3,less than the existing flood control storage capacity of 704570 m3,Therefore,it is in a safe and stable state under flood conditions with a500 year return period(P=0.2%).(2)Based on the simplified Bishop method in the limit equilibrium method and the Swedish circular arc method,the stability of the two-dimensional model of the construction of the tailings reservoir is calculated,and the stability coefficients calculated by the two methods under normal working conditions,flood working conditions and special working conditions are 1.503,1.409,1.366 and 1.303,1.216,1.119,respectively.It means that the tailings pond is in a stable state at this time,but with the application of working conditions,the stability is gradually reduced,which is consistent with the actual situation.(3)Based on the strength reduction method,FLAC3D was used to analyze the stability of the tailings pond in the current state,the late state ten years later and the final state(service life of 50 years).The stability coefficient of the former was 1.121,and the stability coefficient of the latter two were 0.998 and 0.934,respectively.Niuchangping tailings pond had become unstable and had great risk of dam break.(4)By calculating the stability coefficient of tailings reservoir under two/three dimensional conditions,it is found that the stability coefficient calculated by simplified Bishop method under natural conditions is 1.503,which is greater than the stability coefficient calculated by strength reduction method is 1.461,and the minimum value calculated by Swedish arc method is 1.303.The stability coefficients under rainstorm conditions are 1.409,1.320 and 1.212respectively,and the order is the same as above.Moreover,there is little difference in the stability coefficients under two/three dimensional working conditions,that is,the strength reduction method and the limit equilibrium method have little difference in the analysis results of the stability of the tailings pond.(5)Fluent software was used to simulate the dam break of Niuchangping tailings pond,and the maximum flow rate of tailings after dam break was 6.69m/s;The maximum mud depth alluvial thickness is 9.7m;The maximum thickness was generally between 0m and 3m,accounting for 66.48%of the whole disaster affected area.The area of maximum alluvial thickness above 6m accounts for only 4.66%of the total alluvial area.It is concluded that the dam break of the tailings reservoir will affect the downstream office area,industrial park,214Provincial Road and Yalong River.Based on the actual storage capacity,estimated death toll parameters,estimated total economic loss and social environmental impact,the dam-break disaster level is calculated as high impact,and the corresponding safety technical protection measures and safety management countermeasures are proposed for the tailings pond.