## 5 Other Monitoring Analysis and Measurement Verification
### Analysis of Rockburst Hazard Sources Based on CT Technology  
In order to further test the distribution characteristics of lateral abutment pressure in the goaf of the 1300 working face, the distribution characteristics and hazard degree of rockburst hazard sources in the 1301 working face were measured by seismic CT technology. Figure 14 shows the distribution of rockburst risk index C in the detection area of the 80 m wide coal pillar and the 1301 working face. The magnitude of the hazard index detected by seismic CT is closely related to the degree of stress concentration. Therefore, the magnitude of stress concentration in this area can be inferred from the hazard index of rockburst. The danger index of rockburst in the detection area is represented by blue to red, from small to large (that is, stress distribution from small to large). The maximum value of C in the area is 0.7 and the minimum value is \(-0.5\). The rockburst hazard index of most areas in the survey area is less than 0.75, but the rockburst hazard index of coal and rock strata in nearly one-fifth of the survey area is \(0.5\leq\) C \(<\) 0.75, and the above areas are in the middle of the rockburst hazard level. Projecting more than three times the events since 2015 into the C distribution map, it can be seen that the microseismic events are mostly concentrated in the 80 m large coal pillar, the connecting roadway in the 1301 working face, and near the fault structure, especially in the 1301 belt transport down chute. This is because the corresponding area of the coal pillar in the 1301 working face and the 80 m section is comprehensively affected by the lateral bearing pressure, the structure, and other factors of the 1300 working face, the stress distribution is complex, and the risk of rockburst is higher than in other areas, which is consistent with the borehole stress detection results. \begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline \hline \multirow{2}{*}{\begin{tabular}{} \end{tabular} } & \multirow{2}{*}{**Mining Influence Range/m**} & \multicolumn{2}{c}{**Peak Position of Supporting Pressure/m**} & \multicolumn{2}{c}{**Influence Reange of Supporting Pressure/m**} \\ \cline{2-7}  & & **Pull Ahead** & **Side Direction** & **Pull Ahead** & **Side Direction** & **Pull Ahead** & **Side Direction** \\ \hline \begin{tabular}{} \end{tabular} & \(>\)90 & – & 20 & – & \(>\)20 & – \\ \hline \
\begin{tabular}{} \end{tabular} & \(>\)50 & – & 26.5 & – & \(>\)26.5 & – \\ \hline
\begin{tabular}{} \end{tabular} & \(130\) & 120 & 65 & 65 & \(>\)65 & \(>\)65 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison of field measurement results. In order to verify the conclusion of the seismic CT technology evaluation on the rock-burst risk of coal and rock strata, the borehole stress detection test results and seismic CT detection results were compared and analyzed, as shown in Figure 15. According to the number of drilling cuttings and whether there is a dynamic phenomenon in the process of drilling cuttings, the range of the stress concentration area in the surrounding rock of the roadway is defined. It can be seen from Figure 14 that within the range detected by the drilling cuttings method, the area where the drilling cuttings exceed the limit or where dynamic phenomena occur is generally consistent with the distribution of the rockburst hazard area detected by the seismic CT technology, which verifies the reliability of the evaluation method. The adjacent area affected by the lateral abutment pressure of the 1300 goaf was detected using the above two methods. The two methods corroborated the previous analysis results; that is, the distribution range of the lateral abutment pressure of the 1300 working face exceeded the 80 m coal pillar protection area, and the belt transport down chute of the 1301 working face was under the influence range of the lateral abutment pressure, which is the root cause of frequent rockburst events in this area.