## 4 Results and Discussion
### Slope Displacement Analysis  
#### 4.2.1 Displacement Analysis  
The goal formed by underground coal mining causes the overlying strata and ground to be deformed. To determine how mining subsidence proceeds and assess the active state of the ground, ground movement observation stations are usually established in the main sections of coal mining areas, and the frequency of monitoring is usually once a month. In this study, the GNSS real-time monitoring system used the X, Y, and Z coordinates of the monitoring points to calculate the moving trajectory of each point once a day. The influence of mining, rainfall, and terrain factors on the moving trajectory was analyzed. Figure 6 shows that with the advance of the working face, the ground displacement constantly increased at each monitoring point. (1) X-direction displacement. During the advance of the working face, the moving direction at the monitoring points in the initial stage was the opposite of that of the advancing working face. When the working face crossed the monitoring point, the moving direction at the monitoring points was the same as that of the advancing working face. Because the moving direction was consistent with the downhill direction of the slope body, the slope body slip increased the cumulative displacement of the monitoring points. Figure 7 shows the slope body profile with the advance of the working face. (2) Y-direction displacement. With the advance of the working face, the monitoring points all moved toward the center of the goat. When the working face was far from a monitoring point, the horizontal displacement of the monitoring point had a tendency to remain unchanged or to move back to its original position. Figure 6: Ground displacement curves at the monitoring points. (3) Z-direction displacement. With the advance of the working face, the magnitude of sinking constantly increased, except at M07 and M08, which were located far from the working face. The closer the monitoring points were to the center of the coal mining activity, the greater the subsidence. A comparative analysis of the horizontal displacement of the ground at each monitoring point was conducted. The similarities and differences of the moving trends at each monitoring point were related to the topographic conditions at the location of the monitoring point and its ground position above the working face. Monitoring site M06 was located at the bottom of the slope, while M02, M03, M04, and M05 were located at the top of the slope. Because of the poor ground stability at the top of the slope, the horizontal movement at M06 was less than that at M02, M03, M04, and M05. This difference was particularly noticeable on the west side of M05, which was the downward direction of the slope, resulting in an increase in the negative movement of the monitoring point toward the \(Y\)-axis. When the working face was far from the monitoring point, the horizontal movement of the monitoring point was reduced, and the movement was dominated by subsidence. Figure 8 shows the surface movement in the mining process. The horizontal moving track curve of the monitoring point reflects the difference in the moving value at the monitoring point and the trend in different regions over the same time period. (1) Due to coal mining in panels A and B, the movement trend of monitoring points M01-M04 was the same, but the magnitude of movement was different. The largest movement in the X direction was observed at M02 and M03, while the largest movement in the Y direction was observed at M04. As shown in Figure 1, the X direction of M02 and M03 and the Y direction of M04 were close to the downhill direction of the slope body, and the topographic slope had a large influence on the displacement; therefore, they had large moving values. (2) In contrast, M06 was located at ground level in the center of panel A. The horizontal movement in the Y-direction is very small and the movement in the X-direction was the opposite of the other monitoring points.