# The Impact of Fine-Layering of Tailings Dam on the Variation Pattern of Infiltration Lines
## 1 Introduction  
The tailings dam is a non-natural high potential energy dam constructed from the tailings sand of mining sites [1], and tailings ponds are ranked as the world's 18 th among the 93 kinds of accidental and public hazardous disasters [2]. China has more than 10,000 tailings ponds and over 1000 \"head-ponds\" [3], with the largest number of tailings ponds in the world. Dam failure accidents in the \"head dams\" cause tremendous damage to life and property, as well as serious environmental pollution to the downstream area. According to research, dam-break in tailing ponds accidents accounted for 56% [4]. The seepage field is decisive for the safety and stability of tailing dams [5]. The infiltration line is the intersection line between the surface of the infiltration water flow and the cross-section of the dam body; its position is an important factor in evaluating the safety and stability of the tailings dam. Therefore, the infiltration line was known as the tailings pond's \"lifeline\". The study of the infiltration line becomes a prerequisite for research on the safety and stability of tailings ponds [6].  
The infiltration line is an important factor affecting the safety and stability of tailing ponds. Many scholars have conducted comprehensive studies on the seepage field of tailing ponds [7, 8], analytical solutions for infiltration lines [9, 10], the influences of rainfall [11, 12], and dam slope ratios [13, 14, 15] on infiltration lines through model simulation experiments and numerical simulation methods [16, 17]. The permeability coefficient directly affectsthe distribution of infiltration lines, while compactness [18; 19] and consolidation [20; 21; 22] have a significant effect on the permeability coefficient. Many studies have observed that compactness is a major factor affecting the water-holding capacity of soil [23], thus significantly affecting the strength, stiffness, and shear strength of saturated soil [24; 25]. With the increase in compactness, the permeability coefficient becomes smaller and the water-holding capacity becomes stronger [26]. It should be noted that the permeability coefficient and capacity of water holding determine the rise and fall of the infiltration line.  
The numerical simulation models of tailing dams are mostly built using a single soil layer without considering microscopic parameters such as soil type, compactness, and consolidation. Research by [PERSON] et al. has applied the compaction degree of weakly consolidated soils to the modeling process [25]. Similarly, [PERSON] et al. [27] and [PERSON] et al. [28] considered the effect of porosity and pore structure on the permeability coefficient in the rock model, respectively. Therefore, in this paper, different layered characteristics of tailings dam models are established based on the differences in micro-parameters such as tailings sand type, compactness, and permeability coefficient. Rainfall infiltration has a significant effect on the damage to tailings dams; therefore, this paper set up three different conditions of constant head, rainfall, and drainage to carry out simulation research in order to analyze the difference between the changes in the infiltration line of different layering schemes and the fitting percentage of the real situation. According to the simulation results of the three layering schemes under three different conditions, the relationship between compactness and permeability coefficient can be obtained, as well as the influence of different layering schemes on the distribution of the infiltration line of the tailings dam.