*3.1. Geological Setting and Survey Lines Plan*

The Peigou Coal Mine is located in Zhengzhou mining area of the Henan Province, China (Figure 2a,b). The panel 31,071 has a width of 130 m, a strike length of 1100 m (Figure 2c), an average mining height of 7.5 m, an average incline angle of 15◦, and an average burial depth of 300 m. The mining method is a fully mechanized top-coal caving. The roofs of the mining coal seam are mainly fine sandstone and sandy mudstone. The sandstone fissure aquifer of lower Shanxi formation is the upper main aquifer in the local coal mine, and this aquifer is widely distributed in the entire coal mine with an average thickness of 37.13 m. The distance between the bottom interface of this aquifer and the coal seam is approximately 6 m. The aquifer consists of sandstones with medium and coarse grain sizes. Moreover, fractures have been found in certain local regions of the aquifer. In general, the aquifer in Shanxi formation exhibits poor permeability and a weak water yield property. However, there is a reservoir called Modongwang Up Neath (panel 31071), where the risk of reservoir water inrush is high. In order to accurately evaluate the impact of mining damage on Modongwang reservoir and its dam, a surface movement survey station is established on the surface above the panel. Before mining, movement survey lines in the strike and the inclined directions are arranged on the surface above the panel (Figure 2c).

#### *3.2. Subsidence and Subsidence Velocity Curves of Survey Station with Maximum Subsidence*

Figure 3 shows the variation curves of the subsidence velocity and subsidence value at the survey station QZ in the surface strike survey line. Due to survey error, surface subsidence also occurs when the working face is distant. Therefore, this paper mainly considers the increase in subsidence velocity as the basis for judging the beginning of the mining influence. When the distance between the working face and the survey station is about 54 m, this station begins to subside. It can be determined that the working face's leading distance is 54 m, and the advance effect angle is equal to 79.27◦. When the working face passes over this station, the subsidence velocity increases gradually, and then at a distance of 76 m, the subsidence velocity reaches its maximum value of 38.36 mm/d. The surface position subsides most violently at this point. Then, the subsidence velocity gradually decreases, and the subsidence curve of the maximum subsidence position essentially flattens out. When the working face passes over this station by roughly 296 m, the subsidence velocity of this station is 1.67 mm/d, the active phase of the station subsidence ends, and the recession phase starts. Then, the subsidence velocity of this station slows down, and its subsidence value becomes stable at 2140 mm.

**Figure 2.** Location of survey lines, (**a**) map of the People's Republic of China, (**b**) location of the Peigou Coal Mine, (**c**) position relationship between the panel and survey lines.

**Figure 3.** Subsidence velocity and subsidence curves of surface points with maximum subsidence.

*3.3. Variation of Surface Dynamic Movement Parameters in the Working Face Mining Process*
