*5.1. Monitoring of Roadway Deformation*

After hydraulic fracturing, the integrity of 42107AHR at the front of the working face has been significantly improved compared to 42106AHR, as shown in Figure 9. To monitor the stability control effect of the roadway after hydraulic fracturing, two deep base point monitoring stations are set up at 42107AHR (100 m, 125 m, and 150 m in front of the working face). Deep base point separators are installed in the roof, left rib (on the side of the coal pillar), and right rib (on the side of the working face) of each station, with base point installation depths of 3 m and 8 m. The measured value at No. 3 is the largest, and its monitoring data are plotted as a curve, as shown in Figure 10.

**Figure 9.** Picture of roadway control effect.

**Figure 10.** Deep base point displacement monitoring: (**a**) deformation monitoring curve of rib wall rock and (**b**) deformation monitoring curve of the roof.

From Figure 10, t it can be seen that the measured deformation of the left rib is greater than that of the right rib. During repeated mining of 42107AHR, significant deformation began to occur approximately 100 m in front of the working face. The closer the working face is to the monitoring point, the more deformation occurs, and the deformation rate is faster and faster. When the measuring point is 40 m away from the working face, the deformation of the left rib at the 8 m base point of the deep surrounding rock is about 200 mm, and the deformation of the right rib is about 180 mm. The roadway 40 m in front of the working face is reinforced with an advanced hydraulic bracket, which damages the roof monitoring points. The rib monitoring points are supported by hydraulic support ribs to prevent continuous deformation of the ribs. In general, compared to the large deformation of surrounding rock before hydraulic fracturing, the variation of roadway has been effectively controlled at the present stage. The failure depth of surrounding rock is mainly concentrated within 3 m of the surrounding rock, accounting for more than 80% of the total deformation.

#### *5.2. Monitoring of Periodic Weighting Parameters*

To monitor the control effect of hydraulic fracturing on the stope strata behaviors, we analyzed the hydraulic bracket data in the mining process of panel 42106 and panel 42107. The monitoring data hydraulic bracket is shown in Figures 11 and 12.

**Figure 11.** Monitoring data of hydraulic bracket on working face: (**a**) hydraulic bracket data of panel 42106 and (**b**) hydraulic bracket data of panel 42107.

**Figure 12.** Periodic weighting comparison of working face before and after hydraulic fracturing.

From Figures 11 and 12, the following conclusions can be drawn. The average step distance of periodic weighting of panel 42106 is approximately 21.6 m, with an average duration of 7.5 m. The normal load of the hydraulic bracket (LHS) is about 289 bar when the working face is advancing normally, and the average final working resistance of the hydraulic bracket (WRHB) is 15,207 kN. During the periodic weighting process, the average LHS is approximately 395 bar, and the average final WRHB is 22,535 kN. The average step distance of periodic weighting of panel 42107 is about 16.9 m, with an average duration of 4.9 m. The normal LHS is about 265 bar when the working face is advancing normally, and the average final WRHB is 15,146 kN. The average LHS is about 354 bar during the periodic weighting, and the average final WRHB is 19,599 kN, which is less than the rated resistance of the hydraulic bracket of 21,000 kN.

Based on the above analysis, it can be inferred that after implementing hydraulic fracturing measures in panel 42107, the roof fracture line is close to the coal pillar. Hydraulic fracturing can achieve stress unloading on both sides of the working face, promoting the transfer of high stress in the surrounding rock of the roadway. The use of hydraulic fracturing technology promotes timely collapse of the roof, avoids high concentration of stress, and effectively controls the behavior of strong rock layers in the working face.
