## 1 Introduction  
There are very rich mineral resources in China, with billions of tons of tailings discharged every year, and the amount of waste tailings remaining after beneficiation is even greater [1]. The treatment of tailings often takes the form of damming and storing on the surface, which have the advantages of being low cost and simple treatments, and can also realize the resource utilization of tailings. In the long-term operation of tailings ponds, a major problem is the safety and stability of the dam, prone to failure due to seepage damage to the tailings ponds [2]. A large number of studies and engineering practices at home and abroad show that the location of the seepage infiltration line of the dam body is the most critical influencing factor for seepage failure in a tailings dam, and the most critical internal factor affecting the location of the infiltration line is undoubtedly the permeability characteristics of the dam tailings. [PERSON] [3] analyzed the factors influencing the seepage characteristics of tailings dams and the changes in infiltration lines in different dry beach lengths and different upstream and downstream slope ratios in actual engineering based on the basic theory of seepage. [PERSON] [4] used ANSYS to simulate the seepage field of tailings dams,and concluded that the initial dam permeability coefficient had the greatest influence on the change in infiltration line. [PERSON] et al. (2018) took the coarse and fine tailings sands from two mines in Yunnan Province as test materials, compared and studied the seepage laws of coarse and fine tailings sands during dam construction, and found that the damming infiltration line of fine tailings was higher than that of coarse tailings. Although a large number of scholars have analyzed the seepage mechanism, most of them relied on laboratory experiments or numerical simulations, and there are few studies on the relationship between the particle structure and permeability characteristics of the tailings material itself. The tailings are the grinding beneficiation waste, in the form of silty and fine sand, and their particle properties determine the permeability characteristics of the dam body; if the mechanical characteristics of the fine-grained tailings are poor, it is difficult to consolidate the actual project, which brings difficulties to the fine-grained dam. With the development of beneficiation technology, fine-grained damming and high-pile damming will become the main development directions, so it is necessary to study the structural characteristics and permeability characteristics of tailings particles. As an important parameter to characterize permeability characteristics, the permeability coefficient is a key parameter in the field of geotechnical engineering, and a large number of scholars at home and abroad have carried out a great deal of research. [PERSON] et al. (2018) carried out an indoor variable head test on iron tailings, and established a calculation formula for the permeability coefficient of iron tailings from multiple perspectives such as gradation and particle size. [PERSON] (2018) studied the effects of average particle size and the inhomogeneity coefficient of sand on the permeability coefficient by using the constant head test, and found that the permeability coefficient tended to be stable when the inhomogeneity coefficient of sand increased to 11. [PERSON] (2018, 2018) proposed an empirical formula for the permeability coefficient of Corson-Karman specifically for sandy soils, and considered density to be the key parameter affecting the permeability coefficient of soil. [PERSON] et al. (2018) proposed a K = Be\({}^{\text{A}}\) permeability model for cohesive soils based on the formula of the permeability coefficient of sandy soils, where e is the porosity ratio, and A and B are the proportional parameters proposed by different cohesive soils for the Kozeny-Carman formula.