Study On Stability Of Tailings Dam Based On Fluid-solid Coupling

The tailings is one of an important structure to maintain the normal production of mine,its stability is essential for the normal operation of the mine and the safety of surrounding.And for the tailings which not only store tailings but also store water,it is a high potential energy in the "debris flow formation area" and the event of dam and landslide will cause immeasurable losses,therefore,it is necessary to analyze the stability of the tailings dam.While in the previous engineering calculation of the tailing dam stability analysis,it was generally assumed that the soil skeleton in the porous medium is rigid during the seepage process and no deformation,and the permeability coefficient of soil will not change.But in fact,the stability of the tailings dam is not only affected by the stress of the slope,but also affected by the tailings water seepage internal and external.The separate analysis of seepage field and stress field in tailings is not consistent with engineering practice.Therefore,in the aspects of theoretical and practical analysis,it is an important content to study the influence of seepage field and stress field on the stability of tailings dam.For the study of seepage-stress coupling effect on the stability of tailings dam,Liziqing tailings and Hongxin tailings are used as the engineering background,based on seepage mechanics,fluid-solid coupling theory and intensity reduction method,the stability of two tailings which based on the fluid-solid coupling are analyzed through finite element numerical calculation software ABAQUS,the results show that the stability considering the seepage will reduce compared with the stability considering the stress,while the stability considering the fluid-solid coupling will increase compared with the stability considering the seepage.The main work of this paper are as follows:(1)Chose a typical,well-established third-state tailings,Liziqing tailings,and a pile of non-standard,fifth-state tailings Hongxin tailings after redesigning as the research object,to simulate the change of the tailings stability after considering the fluid-solid coupling,and make a comprehensive comparison.(2)According to the basic principle of coupling calculation of seepage field and stress field,first,the mechanism of seepage field on stress field and the mechanism of stress field on seepage field are analyzed from the physical point of view,and it is pointed out that the two fields are interrelated and interact;And then the mechanism of interaction between the two fields is analyzed from the mathematical level.It is concluded that the head difference in the seepage field will lead to the change of the stress state of the medium,so that the displacement of the medium will change,and the displacement will make the porosity and void ratio in the seepage field change,and then lead to the change of the permeability coefficient and the change of the seepage field.Finally,the mathematical model considering the fluid-solid coupling and its solving method are deduced.(3)The finite element numerical calculation software ABAQUS was used to calculate the dam stress and deformation characteristics and the stability safety factor under the seepage field,stress field and seepage-stress coupling field.Compared with the stability safety factor which considering seepage field and stress field,the stability safety factor of Liziqing tailings reduce 0.178,and the stability safety factor of Hongxin tailings reduce 0.297,which indicates that the hydrodynamic pressure of the seepage flow in the seepage will affect the stability of the tailings dam to a great extent;While compared with the effect of seepage-stress and the effect of seepage alone,the two tailings dams have a certain degree of decrease in horizontal displacement,vertical displacement,stress and deformation,seepage flow rate and incremental displacement,and the stability safety factor of Liziqing tailings increase 0.036,its infiltration line is reduced 0.2?0.3m;and the stability safety factor of Hongxin tailings increase 0.012,its infiltration line is reduced 0.1?0.15m.Indicating that the interaction between the groundwater and the tailings will have a favorable and positive effect on the tailings dam.Considering the effect of fluid-solid coupling,showing the same change rule in the analysis of tailings stability include well-packed third-state tailings pond Li Ziqing tailings and a pile of nonstandard,fifth-state tailings pond Hongxin tailings after redesigning.and the results are applied to the design of the tailings dam,it is concluded that the tailings dam can slightly increase the tailings dam slope angle while ensuring the stability,cut the engineering quantity and cost savings.