## 3 Analysis of Test Data
### Analysis of Surrounding Rock Stress Results  
The stress-time curve of the surrounding rock in the first test group is depicted in Figure 11. The examination of the figure reveals that the peripheral rock at each point around the tunnel, under the initial stress state, is subjected to compressive stress. The magnitude of the stress is directly correlated with the depth of burial, with greater depths resulting in higher initial stress values. The initial stress value of the peripheral rock at the arch top is 7.449 kPa. The average initial stress value of the peripheral rock at the arch shoulder is 8.497 kPa. The average initial stress value of the peripheral rock at the arch waist is 8.646 kPa. The average initial stress value of the peripheral rock at the foot of the arch is 9.079 kPa. and the average initial stress value of the peripheral rock at the bottom of the arch is 10.113 kPa. After the excavation of the upper middle 1 guide hole, the peripheral rock at the arch top undergoes a rapid release of the original stress, resulting in a swift decrease in compressive stress from 7.188 kPa to 2.870 kPa. Subsequently, the stress stabilizes under the influence of the supporting structure. The upper guide hole of the second ring, situated adjacent to the peripheral rock of the arch, experiences a gradual increase in peripheral rock stress, as the stress released after excavation is transferred to the arch. The stress value after the completion of the excavation of the middle and upper 2 guide holes reaches 3.680 kPa. The excavation of the lower guide hole of the second ring and the third ring section exerts a lesser influence on peripheral rock stress, leading to a slow and fluctuating increase in stress. The stress value after the completion of the excavation of all guide holes amounts to 4.213 kPa. Upon the removal of the temporary support, the peri  
Figure 10: Surface deformation time history curve of the second group. due to disturbance, resulting in a compressive stress value of 5.241 kPa when all temporary supports are removed. The stress distribution of the left and right surrounding rock exhibits symmetry, and the stress variation pattern is essentially identical. Consequently, the arch shoulder, arch waist, and arch foot are collectively considered as the left surrounding rock for analysis. Following the excavation of the upper left 1 guide hole, the compressive stress undergoes a rapid decline from 8.342 kPa to 4.860 kPa. Subsequent excavation of the upper left 2 guide holes leads to a slight increase in stress to 5.701 kPa, after which the stress value stabilizes. Minimal fluctuations occur in the subsequent excavation phases, and upon the completion of all guide holes, the stress value reaches 6.035 kPa. The removal of the temporary support induces fluctuations in the surrounding rock stress value due to disturbances. Specifically, when all temporary supports are removed, the compressive stress of the surrounding rock fluctuates, settling at a value of 5.916 kPa. The arch-waist perimeter rock experiences stress release after the excavation of both upper-left 1 and lower-left 1 guide holes, resulting in a decrease in stress values. Specifically, during the excavation of the upper-left 1 guide hole, the stress decreases from 8.854 kPa to 7.600 kPa, and during the excavation of the lower-left 1 guide hole, it decreases from 8.175 kPa to 7.514 kPa. Subsequent excavation of the adjacent upper-left 2 and lower-left 2 guide holes induces a gradual increase in stress values, reaching from 7.401 kPa to 7.748 kPa during the excavation of upper-left 2 guide hole and from 7.810 kPa to 8.082 kPa during the excavation of lower-left 2 guide hole. Upon the removal of the temporary support, the initial support undergoes inward shrinkage and deformation due to the lack of support. At the arch waist, the surrounding rock briefly forms a critical surface, causing a decrease in stress values. The compressive stress of the surrounding rock settles at a value of 6.431 kPa upon the completion of the removal of temporary support.