## 4 Results and Discussion  
### Slope Movement Velocity Analysis  
In the process of underground coal seam mining, the overlying strata will experience subsidence, tilt, horizontal movement, horizontal strain, and other deformations, which often lead to the destruction of surface buildings, slope slippage, and surface cracks. In this study, the dynamic deformation of slope and the active state of the overlying strata were assessed by setting real-time GNSS monitoring points. According to the X, Y, and Z coordinates of each monitoring point, the displacement and moving velocity of the monitoring points in 3D space were calculated and the factors influencing the deformation of the slope body in the mining area were analyzed. According to Figures 3 and 4:  
(1) After operating the monitoring system, the working face in panel A advanced 10 m beyond monitoring point M01, and its velocity in each direction was relatively small (within 20 mm/d) and stable. After 50 days of monitoring, because the working face in panel B was close to M01 (about 100 m), the influence of mining ahead of the monitoring point increased its X and Z directional movement. When the distance between the working face and M01 was more than 386 m, the Vz of the monitoring point was slightly larger than the Vx and Vy. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Signal** & **Time Precision** & **Static Surveying Accuracy** & **Differential Protocol** \\ \hline BDS: B1/B2/B3 & & Horizontal: 2.5 mm + 1 ppm; & \\ GPS: L1/L2/L5 & 20 ns & Elevation: 5.0 mm + 1 ppm & RTCM 2.x/3.x, CMR \\ GLONASS: L1/L2 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The parameters of UB380 board module. Figure 4: One-dimensional moving velocity curves. Figure 3: Map of the advancing work face of the mining activity in panels A and B. (2) When the working face in panel A passed through M02, the Vy and Vz at the monitoring point gradually decreased, and Vx initially increased and then decreased. As the distance from the working face to M02 gradually increased, the Vx became larger than the Vy and Vz (i.e., the movement in the X direction was more active because M02 was located at the top of the slope), and the disturbance in the downhill direction (X direction) of the slope was greater than the disturbance in the other directions. The velocity in the three directions then became stable at about 20 mm/d. Similarly to at M01, Vz was slightly larger than Vx and Vy when the distance between the working face and M02 exceeded 349 m. The velocity curve at this point increased suddenly at 43 days, especially for Vx and Vy, which was caused by the continuous rainfall shown in Figure 5.  
(3) The movement velocity at M03 and M02 was very similar. After monitoring started, Vy and Vz at M03 gradually decreased and eventually stabilized at 30-40 mm/d, while Vx initially increased and then decreased, before becoming more active. Because M03 was located on the shoulder of the landslide slope, the moving velocity at M03 was higher than at M02. When the distance between the working face and M03 in panel A was approximately 300 m, Vx and Vy were synchronized, and Vz became slightly larger. After 67 days of monitoring, all recorded velocities were less than 20 mm/d. (4) At M04, Vx initially increased and then decreased, Vz increased to around 30 mm/d, and Vy decreased to 20 mm/d. When the distance between the working face and M04 was large, Vx and Vy were synchronous and Vz increased slightly, but all were less than 20 mm/d. Because M04 was located at the outer boundary of panel A, its velocity was less than M03, but its location was close to the downhill direction of the slope body, and therefore it was still larger in the X and Z directions. (5) At M06, which was located in the middle of panel A close to the bottom of the slope, Vx and Vy were very low (10 mm/d) and the plane movement was small. As the distance between the working face and M06 increased, Vz gradually increased and then decreased, and the vertical direction was severely affected by the mining activity.