## 3 Analysis of Test Data
### Analysis of Lining Stress Results  
Figure 13 illustrates the time course curve of lining stress for the first set of tests. Following the excavation of the upper left 1 guide hole, the surrounding rock undergoes deformation towards the excavation chamber. The supporting structure, in turn, bears the force exerted by the surrounding rock. Consequently, the lining stress values of the left arch shoulder, left arch waist, left elevation arch, and the upper left diaphragm wall all experience an increase. Specifically, the stress value of the left arch waist rises from 2.454 kPa to 7.174 kPa, the left elevation arch stress increases from 0.158 kPa to 1.456 kPa, and the stress value of the upper left diaphragm wall rises from \(-\)0.973 kPa to 7.730 kPa. After excavating the upper-right 1 guide hole, the lining stress values for the right arch shoulder, right arch waist, right elevated arch, and upper-right diaphragm wall all experience an increase. Specifically, the stress value of the right arch waist rises from \(-\)0.251 kPa to 5.328 kPa, the stress value of the right elevated arch increases from 0.884 kPa to 1.261 kPa, and that of the upper-right diaphragm wall rises from 0.579 kPa to 8.096 kPa. The left side of the supporting structure is relatively unaffected by the excavation of the upper-right 1 guide hole, with stress values showing only slight fluctuations. Following the excavation of the middle-upper 1 guide hole, the overall superstructure experiences an elevation in stress values. The lining stress of the arch top increases from 1.103 kPa to 5.556 kPa, the left arch waist stress rises to 9.583 kPa, the right arch waist stress increases to 7.239 kPa, and the left superelevation arch stress reaches 2.679 kPa. The stress values of the right superelevation arch and left upper diaphragm wall rise to 1.675 kPa and 9.908 kPa, respectively, while the right upper diaphragm wall stress increases to 11.432 kPa. This indicates that the applied vault lining and the middle superelevation arch connect the two sides of the supporting structure into a unified whole, transferring the force exerted by the overlying surrounding rock to the entire superstructure. Consequently, the overall stress value of the structure increases. The arch top and diaphragm wall bear the direct vertical soil pressure, resulting in higher stress values compared to the rest of the structure. The stress values of the right arch waist and right upper diaphragm wall decrease to 2.427 kPaand 10.936 kPa, respectively, while the stress values of the right foot of the arch, the right lower diaphragm wall, and the right superelevation arch rise to 1.126 kPa, 6.924 kPa, and 3.377 kPa, respectively. Construction disturbances lead to damage in the support structure of the remaining guideway, causing stress values to fluctuate. Following the excavation of the middle and lower 1 guide hole, stress values for the upper left diaphragm wall, upper right diaphragm wall, left elevation arch, and right elevation arch decrease to 7.529 kPa, 8.142 kPa, 2.761 kPa, and 2.486 kPa, respectively. Simultaneously, stress values for the left arch waist, right arch waist, left arch foot, right arch foot, lower left diaphragm wall, lower right diaphragm wall, and the bottom of the arch rise to 5.524 kPa, 4.374 kPa, 2.178 kPa, 2.484 kPa, 10.485 kPa, 10.468 kPa, and 3.179 kPa. This indicates that after the excavation of the middle and lower guiding tunnel and the application of the arch bottom supporting structure, the supporting structure of the first ring tunnel connects into a cohesive whole, leading to redistributed and downward concentrated lining stresses. Figure 12: The time-history curve of surrounding rock stress in the second group of the test. (**a**) Stress time curve of the surrounding rock at the top and bottom of the arch. (**b**) Stress time curve of the surrounding rock at the arch shoulder. (**c**) Stress time-course curve of the perimeter rock at the arch girdle. (**d**) Stress time curve of the surrounding rock at the foot of the arch.