# An Evaluation of Mine Water Inrush Based on Data Expansion and Machine Learning
## 2 Materials and Methods  
The occurrence of water inrush accidents in coal mines is the result of a variety of influencing factors. The primary causes of water inrush accidents are fault structure failure, which can impair the aquitard's resistance to deformation, weaken the integrity of the coal seam, and decrease the strength characteristics of the rocks in the coal seam. The water barrier layer of the coal seam plays a major role in preventing water inrush, and its thickness and mechanical characteristics dictate this ability. The force behind the water inrush is the aquifer's water pressure, which also has the impact of enlarging and eventually shattering the rock layer crack. The aquifer's water content serves as a gauge for the damage caused by water inrush, with high water pressure and an abundance of water sources being the most detrimental factors. Water inrush is significantly influenced by mine pressure. The water barrier layer will break due to mine pressure, which will also widen existing rock layer fissures. This will thin the effective water barrier layer and provide the conditions for water inrush in coal mines.  
The Ministry of Coal proposed the water inrush coefficient method [21]. In theory, the standard of water inrush prediction is set as the water pressure value received by unit water barrier, and the concept of water inrush coefficient is put forward. The \"lower three belts\" theory, the \"two-zone\" model, the \"lower four belts\" theory, the \"Strong Permeability Channel\" theory, the \"KS\" (Key Strata) theory, etc., were all born out of this. Professor [PERSON] of Shandong University of Science and Technology proposed the theory of the \"lower three belts\" through the analysis and finite element calculation of the water barrier layer of the floor. In the theory, the coal seam floor is divided into three zones with different water barrier capacity, including the water damage zone guided by the floor mining, the effective protective layer zone and the confined water lift zone. Based on the theory of \"lower three belts\", the theory of \"ower four belts\" is established based on damage mechanics, fracture mechanics and mine pressure theory. The theory divides coal seam floor into mine pressure zone, damage zone, original damage zone and original guide height zone. According to the theory of Strong Permeability Channel, there are two kinds of water inrush channel: when there is the original water inrush channel directly connected with aquifer water source in coal mine floor; When there is no original channel, the mining activity destroys the weak link of the floor and causes it to deform and form a strong seepage channel.  
These prediction methods mostly rely on empirical formulas and qualitative analysis, which is difficult to make full use of the multi-dimensional characteristics of water inrush, and the prediction accuracy is greatly limited.  
The analysis reveals that the five first-level indicators of aquifer conditions, aquifer conditions, coal seam conditions, structural conditions, and mining conditions, as well as the corresponding twelve secondary indicators, are the primary factors affecting the water inrush from the coal floor. This conclusion is based on the summary of prior studies. Table 1 shows the influencing factors of coal seam water inrush.