Study On Stability Of High Tailings Dam Based On Fluid-Solid Coupling

The stability of tailings accumulation dam is a complex system problem,which is directly related to the safety of the surrounding areas.In this paper,combined with the actual project of Majiatian tailings dam in Panzhihua City,Sichuan Province,the corresponding model is established by using Geo-Studio software and Midas GTS NX software based on finite element method and PFC2 D software based on discrete element.The fluid-solid coupling analysis is carried out on the seepage field,static stability and dynamic stability of Majiatian tailings dam,and the evolution of local landslide of particle flow is simulated.The main contents and conclusions of this paper are as follows:(1)Based on the engineering geological survey data,the basic physical and mechanical indexes of tailings and related materials are obtained and verified through field tests and indoor geotechnical tests.(2)Based on the seepage theory of saturated-unsaturated soil,the seepage field and pore water pressure distribution of Majiatian tailings dam under normal and flood conditions are analyzed.The results show that the calculation results of pore water pressure and total hydnaulic head of two-dimensional and three-dimensional seepage field are similar.Because the three-dimensional seepage model considers the seepage field of two reservoir areas at the same time,the seepage line of the middle and lower reaches is slightly higher,but all meet the requirements of the code.(3)Based on the analysis of seepage field,the fluid-solid coupling analysis of tailings dam is carried out,the static stability under normal and flood conditions is studied,and the effects of different dry beach length and different two-dimensional limit equilibrium slice method on the stability calculation results are compared.The results show that the length of dry beach has obvious influence on the static stability of tailings dam,and Majiatian tailings dam can work as usual under normal and flood conditions.(4)The two-dimensional and three-dimensional finite element calculations of Majiatian tailings dam under special working conditions is carried out by using timehistory analysis method,the dynamic response law and safety and stability coefficient are obtained,and a variety of methods are used to comprehensively distinguish the potential liquefaction area.The results show that there is no instability failure of Majiatian tailings dam under special working conditions,and liquefaction occurs during the earthquake,but the liquefaction area has little effect on the stability.(5)The biaxial simulation test platform is established by using PFC2 D software based on discrete element.According to the macroscopic parameters of each tailings stratum in the reservoir area,the appropriate contact model is selected for trial calculation,and the micro-parameters of each soil layer in the sliding body are obtained.(6)Based on the slip surface obtained by two-dimensional finite element analysis,the particle flow simulation of tailings during the local landslide of tailings dam is carried out by Ball-Wall method,and the displacement,velocity,contact force and porosity of tailings are studied.The results show that after the seismic acceleration is magnified,the sliding failure of tailings accumulation dam occurs and the bulging deformation occurs in the middle of the slide.But there is no great threat to the downstream area.The innovations in the research work of this paper mainly include:(1)Based on the fluid-solid coupling theory,the study of static and dynamic stability is carried out,which is more in line with the actual engineering situation after considering the coupling effect of seepage field and stress field.(2)Combined with the potential slip surface calculated by the finite element limit equilibrium method,the particle flow Ball-Wall method for slope landslide analysis is used to simulate the dam break of tailings dam.