## 4 Engineering Applications and Discussion
### Discussion  
Figure 7 shows the change curves of monitoring data for the displacement (\(D\)) of surrounding rocks in the cross-section of the supported roadway.  
The sink rate of the roof aligns with the convergence trend in the horizontal direction (Figure 7). The surrounding rock exhibits a significant convergence deformation rate, with the deformation amount exceeding 20 mm within the first 5 days of the roadway support. The convergence rate of the two sides is 5.50 mm\(\cdot\)d\({}^{-1}\), which is slightly higher than the sink rate of the roof. Subsequently, the convergence deformation rate rapidly decreases and stabilizes after one month. The abrupt change in the convergence rate of the surrounding rock during the initial stage can be attributed to two primary factors. First of all, the relative deformation of the rock mass increases under gravity, which increases the anchoring force of the bolts and anchor mesh in the early support stage. The deformation of rock mass is constrained only when the anchoring force of the bolts and anchor mesh is sufficiently robust. Second, the concrete sprayed on the surface of the surrounding rocks requires a certain curing duration to reach its specified strength.  
Figure 6: Deformation monitoring of roadway roof and surrounding rocks on two sides.  
The initial concrete strength is directly proportional to the curing duration. Insufficient concrete strength can lead to localized deformation of the rock mass prior to complete solidification. As support time progresses, the surrounding rocks undergo certain displacements. Concurrently, the strength of the concrete and the anchoring effect of the bolts and mesh rapidly increase, which ultimately enhances the strength of the surrounding rocks in the anchoring zone.  
The behavior of the rock mass is influenced by changes in stress distribution within the rock, which evolves in response to the applied support. After one month, the deformation of the surrounding rocks is controlled, with displacements of the roof and horizontal sides confined to less than 35 mm. This indicates that the joint support pattern effectively meets the stability requirements of the surrounding rocks.  
Subsequent investigations confirm that the adoption of this integrated support approach for the roadway in this section has successfully prevented rib spalling and roof caving. The cross-section of the roadway maintains its original state, ensuring both stability and long-term support effectiveness. The integration of anchor bolts, anchor mesh, and shotcrete consolidates the surrounding rocks into relatively cohesive units, thereby improving their mechanical properties and resilience under stress.  
This case underscores the importance of understanding the damage mechanisms during excavation. As highlighted by [PERSON] et al. (2019) assessing the quality of rock excavations is crucial for developing effective support solutions that enhance stability. Furthermore, [PERSON] et al. (2020) emphasize the significance of recognizing deformation characteristics and support requirements in underground settings. This comprehensive support system not only addresses immediate stability concerns but also enhances the overall behavior of the rock mass under varying rock mass quality conditions, drawing valuable lessons from existing literature on rock excavation and support practices.