## 4 Distribution Law of Floor Stress and Bidirectional Stress Ratio in the Working Face
### Validation of the Reasonableness of the Numerical Simulation  
From the above distribution, it can be seen that the bottom-pumping roadway is arranged in the medium-grained sandstone of the bottom plate of the working face, and the distance from the working face is 15 m. Therefore, the vertical stress cloud map at the position of 15 m of the bottom plate of the working face is intercepted as shown in Figure 7 below. The vertical stress of monitoring line 1 is arranged in the middle of the position of 15 m at the bottom plate of the working face, and the stress monitoring curve of the vertical stress monitoring line is extracted as shown in Figure 8 below. According to the vertical stress cloud diagram at 15 m on the bottom plate of the working face in Figure 7, it can be seen that within the projection range of the coal pillar outside the hollow area, the vertical stress appears to be a stress-concentration phenomenon, the vertical stress of the surrounding rock outside the filling area at the edge of the projection of the hollow area decreases greatly, the vertical stress of the surrounding rock in the range of the filling area is gradually restored, and the closer to the middle of the hollow area, the better the effect of the vertical stress. Combined with the vertical stress distribution curve of monitoring line 1 in Figure 8, it can be seen that the vertical stress of the surrounding rock in the range of 80 m in front of the working face increases gradually, the vertical stress reaches a maximum of 23.5 MPa at the position of 10 m in front of the working face, the vertical stress decreases sharply in the range of 23 m behind the working face, the vertical stress reaches a minimum of 3.6 MPa at this position, the vertical stress gradually increases in the range of 24-100 m behind the working face, and the vertical stress decreases gradually in the range of 24-100 m behind the range of 24-100 m behind the working face. In the range of 24-100 m behind the working face, the vertical stress of the surrounding rock increases gradually, and the vertical stress of the surrounding rock stays above and below 11 MPa. Therefore, the vertical stress from the edge of the model to the middle of the mining area can be divided  
Figure 8: Vertical stress distribution curve of monitoring line 1. Figure 7: Vertical stress cloud at 15 m on the bottom plate of the working face. into the original rock stress area, the stress increase area, the stress decrease area, and the stress stabilization area, and its change is in line with the distribution law of the supporting pressure of the working face's bottom plate after the coal seam is mined [34]. The change occurs due to the distribution of support pressure in the working face after mining, which verifies the accuracy of the numerical simulation. Characteristics of the Bidirectional Stress Ratio Distribution of the Bottom Plate of the Working Face  
Vertical and horizontal stress monitoring lines 2, 3, and 4 were arranged in the middle of the working face (Figure 9), and the distance from the working face is 15 m, the distance to the right of the middle of the working face is 40 m, and the distance outside the projection of the coal pillar is 15 m. The monitoring lines all went along the normal direction of the working face, and the distribution of the peripheral rock stress and the bidirectional stress ratio at different locations of the bottom plate of the working face were obtained as shown in Figure 10.  
According to the monitoring curve of the stress and the bidirectional stress ratio at different locations in Figure 10, it can be seen that when the vertical stress increases sharply, the horizontal stress increases slightly, and when the vertical stress decreases sharply, the horizontal stress decreases less, which means that that there is a weakly sensitive feature of the vertical stress and the horizontal stress of the surrounding rock at the bottom plate of the working face.