## 5 Theory and Field Test Verification
### Field Application Studies
#### 5.2.3 Evaluation of the Positioning Capability  
(1) Numerical simulation evaluation  
The source location accuracy and sensitivity are calculated for the proposed site layout scheme. According to the test results of the acoustic characteristics of the mine, the P-wave velocity is 4200 m/s, and the P-wave arrival error is 1.5 ms. Drawing the positioning accuracy map, take the magnitude \(M_{L}=1\). Drawing the sensitivity map, the effective  
Figure 10: Optimization curve of IPSO.  
Figure 9: Layout scheme of on-site microseismic network.  
number of digits is 5, and the minimum peak particle velocity that the microseismic sensor can resolve is 0.09 mm/s. Draw the expected standard error map and the contour map at different depths, as shown in Figures 11 and 12.  
Figures 11 and 12 show the positioning error and sensitivity distribution of the bottom plate (920 m) and the top plate (970 m) of the working surface 2305, respectively. Different colors are used to represent the positioning error and sensitivity. The numerical units on the positioning error color scale and the sensitivity color scale are m and Richter scale values, respectively. It can be seen that for the coal seam roof and floor of the working face 2305, the source positioning errors of the key monitoring areas are all within the range of less than 20 m, indicating that the working face back to the mining body and its surrounding rocks are basically in the area with high source positioning accuracy. In addition, the source positioning accuracy is still in the range of less than 20 m within the range of not less than 200 m along the working face. The source positioning accuracy decays rapidly as it moves away from the sensor array along the working face. Therefore, from the perspective of source location accuracy, the sensor arrangement scheme not only satisfies the requirements of location accuracy but also makes the microseismic monitoring system economical.  
Figure 11: Evaluation of sensor arrangement on the coal seam floor (920 m). (a) Positioning errors. (b) Sensitivity.  
It can be seen from Figures 11 and 12 that, regardless of the mine roof or floor, the minimum magnitude that can be measured in the ore body and its surrounding rock of the key monitoring area is \(-3.26\), and the local position of the floor can reach \(-3.31\). In the area around the working face, the minimum measurable magnitude of the top plate is \(-2.35\), and that of the bottom plate is \(-2.48\). Therefore, the sensor arrangement scheme has sufficient system sensitivity.  
(2) Field test evaluation  
To further evaluate the rationality of the network layout, taking the three blasting tests of the mine stope on 8 November 2019 as examples, the positioning calculation was carried out according to the coordinates of the geophone and the corresponding arrival time. Compared with the measured blasting position, the positioning coordinates are as shown in Table 4. Using the simplex localization method in the microseismic system, the blasting event was effectively located. The test results are shown in Table 5.  
Figure 12: Evaluation of sensor arrangement on the coal seam roof (970 m). (**a**) Positioning errors. (**b**) Sensitivity.  
From the comparison in Table 5, it can be seen that the maximum positioning errors of the three coordinate directions are 5.6 m, 8.7 m, and 7.1 m, respectively. The average positioning errors are 4.0 m, 7.8 m, and 5.0 m, respectively, the maximum spatial positioning error is 12.2 m, and the average is 10.3 m. Therefore, the positioning accuracy can meet the needs of engineering monitoring. From the coverage rate of the monitoring area, the effective range factor \(F_{V}\) of the coal seam floor is 0.7831, while the effective range factor \(F_{V}\) of the coal seam roof is 0.7880. The above research shows that the layout of the microseismic station network in Xiaishije Coal Mine is reasonable and meets the needs of the mine's microseismic monitoring.