Seepage Failure Characteristics Of High Dam For Fine Tailings

There are a large number of tailings dams in China.Due to the different years of construction and the influence of accumulation quality and management level,there are a large number of dangerous tailings dams.High tailings dams containing fines are more prone to disease.In tailings dams disasters,seepage damage occupies a high proportion.Due to the finer tailings particles,the sedimentary structure and seepage characteristics are affected,and the risk of seepage failure in high dams is exacerbated.This complicates the problem of seepage failure of high tailings dams containing fines.Fine iron tailings are taken as the research object.Through XRD detection,electron microscope scanning,engineering exploration,consolidation permeability test,triaxial shear test,consolidation permeability failure test,sand tank test,and numerical simulation analysis,the characteristics of tailings seepage failure under the influence of fine particles,sedimentary structure and high consolidation pressure were analyzed.1)Based on the particle contact state theory,the iron tailings are divided into four types.XRD testing was conducted to analyze changes in clay mineral content under the change of the content of clay and silt particles.The tailings particle geometry was characterized by circularity,flatness and roundness and compared with natural sand.Through drilling sampling and laser particle size analysis,the gradation and particle size distribution characteristics of tailings were determined.The tailings consolidation characteristics and one-dimensional consolidation model are analyzed.2)The consolidation permeability test was conducted.The compressibility of four types tailings was analyzed,and the variation characteristics of void ratio with consolidation pressure of reshaped tailings,vertical tailings and horizontal tailings were determined.The variation of tailings permeability coefficient under the influence of sedimentary structure,high fine particle content and consolidation pressure was analyzed.The calculation method of tailings average pore diameter and permeability coefficient are proposed.3)Through triaxial shear test and Pdyna numerical simulation,the strength characteristics of reshaped tailings and vertical tailings with different fine particle contents were analyzed.The mechanical characteristics were analyzed from the perspective of strong and weak force chain.The influence of the angle of the tailings sedimentary structure on its strength characteristics was determined.4)Consolidation permeability failure test and sand tank test were conducted.The seepage failure characteristics of structural tailings under the influence of different fines content and consolidation pressure were analyzed.Based on the average pore diameter method,a method to discriminate the seepage failure mode is proposed.The critical gradient of the seepage failure of tailings is analyzed,and the calculation method is proposed.The evolution process of the seepage failure of tailings dam is further analyzed.5)Numerical simulation analysis was conducted to determine the relationship between the length of the tailings dam safe dry beach and the fine particle content,consolidation pressure and tailings structure of the discharged tailings.The relationship between the buried depth of the tailings dam wetting line and the dry beach length under the influence of the above three factors is clarified.The impact of tailings dam failure is analyzed,and corresponding suggestions for tailings dam safety management are proposed.The results provide a more accurate calculation model of tailings permeability coefficient,a method for judging seepage failure mode and a critical hydraulic gradient calculation method for tailings dam seepage failure analysis.It’s significant for preventing seepage damage of tailings dams and maintaining the safe operation of tailings dams.Figure 156;Table 56;Reference 168...