## 3 Deformation and Failure Characteristics of Surrounding Rock of Roadway
### Deformation Law of Roadway Surrounding Rock  
During the excavation of airway #1409, I analyzed the convergence between the roof and floor as well as the convergence between the ribs. I selected a typical measuring point to study the changes in monitoring data. In Figure 5a, you can see the monitoring results of airway #1409 during the excavation period. The largest convergence between the roof and floor was 1880 mm, while the largest convergence between the ribs was 1100 mm, both occurring after 189 days of excavation.  
The deformation of the surrounding rock was significant, with rapid growth rates of both roof-to-floor convergence and rib-to-rib convergence in the initial 77 days. During this time, the roof-to-floor convergence reached 1300 mm and the rib-to-rib convergence reached 800 mm, indicating substantial deformation in the surrounding area during the excavation. However, the roof-to-floor convergence and its growth rate were much larger than the rib-to-rib convergence.  
As a result of the significant deformation during the excavation, there were five repair activities labeled as a, b, c, d, and e in Figure 5a. Among these activities, reducing the floor thickness was a common countermeasure. Table 1 summarizes the five reductions in floor thickness, with the largest reduction being 550 mm. This required a considerable amount of supporting materials and labor. Unfortunately, even with these repair activities, the roof-to-floor convergence did not stop, and the deformation continued to grow rapidly.  
Figure 4: Mine pressure monitoring station in 1409 airway.  
The results of the monitoring of the separation layer of the roof are presented in Figure 5b. The shallow point has a maximum separation value of 155 mm, while the deep point has a maximum separation value of 167 mm. It takes 14 days for the roof separation value to exceed the critical threshold. Statistical analysis of the on-site roof separation values indicates that most of them are greater than 100 mm, with some even exceeding 200 mm. This significant separation layer on the roof, along with its instability, provides additional evidence that the support plan for the roof is inadequate in dealing with the high-stress concentration in the area.  
The variations in load for the bolts and anchor cables during roadway excavation are shown in Figure 5c,d. The load on the anchor cable increases rapidly, reaching a maximum load of 330 kN. The 1 and 2 m anchor cables reached a load of 330 kN in just 27 days. The load on the anchor bolt, on the other hand, has a maximum load of 124 kN. The load on the anchor cable and the anchor bolt exhibit different patterns. While the load on the anchor cable increases quickly and can reach higher values, the load on the anchor bolt remains relatively low. These results indicate that the combined action of the anchor cable and bolt support is not effective, leading to increased stress on the roof anchor cable and subpar  
\begin{table}
\begin{tabular}{c c} \hline \hline
**No.** & **Floor Heave (mm)** \\ \hline a & 450 \\ b & 550 \\ c & 200 \\ d & 100 \\ e & 100 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Floor heave of the surrounding rock deformation monitoring station #3.  
Figure 5: Evolution characteristics of the deformation and supporting loads of the surrounding roadway rock. (**a**) surrounding roadway deformation; (**b**) the BSRS; (**c,d**) loads of cables and bolts.  
support from the anchor bolt. Additionally, due to the significant difference in weight between the two components, the anchor cable is damaged by the mining stress before the anchor bolt.