# Study on the Fracture Resistance of Mixed Fiber Concrete Lining in a Reverse Fault Tunnel
## 5 Calculation of the Reverse Fault Tunnel  
In this paper, we mainly study the impact of inverse fault misalignment on tunnel lining misalignment performance under different mixed fiber admixture conditions, analyze the stress-strain and damage of lining during fault misalignment according to numerical simulation monitoring results, set up key lining monitoring points shown in Figure 7, monitor the maximum principal stress, longitudinal strain, and shear strain of the lining, including the secondary lining three indicators, and carry out a detailed analysis of the corresponding tensile and compressive injuries. In this section, the parameters of the addition and \(\mathrm{L/D}\) ratio of steel fiber and polypropylene fiber are selected as 0.5% (\(\rho_{\mathrm{sf}}\)), 30 (\(\mathrm{l_{sf}}/\mathrm{d_{sf}}\)), 0.05% (\(\rho_{\mathrm{pf}}\)), 30 (\(\mathrm{l_{pf}}/\mathrm{d_{pf}}\)), and Figure 8 gives the specific numerical variations of the maximum principal stress values, longitudinal strains, shear strains, compressive, and tensile damage variables distributed along the longitudinal direction of the tunnel in the five monitoring points. Figure 6: Vertical displacements at tunnel vault (compared to [PERSON]’s data [32]). Figure 7: Monitoring points of the secondary lining. From Figure 7(a), it can be obtained that the influence range of reverse fault misalignment on the maximum principal stress of the lining is about 87.5 m in the vicinity of the fault zone, and the maximum stress values of the five key parts within the range fluctuate significantly, but the difference between the extremes of the values is not large, in which the extreme values of the arch crown and the arch haunch are relatively large, respectively, 2.79 MPa and 2.74 MPa, while the extreme value of the invert arch is relatively small, 2.22 MPa. At the same time, it can be found that the maximum principal stress extreme values of the arch crown and arch haunch are biased towards the hanging wall, in which the arch crown is subjected to large tensile stress in addition to the hanging wall, and a small area of compressive stress appears in the football; the maximum stress values of the arch springing, arch springing, and invert arch are biased towards the football, in which the arch springing is opposite to the arch crown and is subjected to a large range of tensile in the football, and part of the compressive area appears in the hanging wall. Figure 7(b) shows that the longitudinal strain changes are concentrated in the range of 100 m near the reverse fault, and it can more clearly reflect the longitudinal strain of the lining structure in the hanging wall and football, which are subjected to different tensile and compressive properties. Among them, the arch crown and arch haunch are tensile in the fault zone near the hanging wall and compressive near the football, while the arch sidewall, arch springing, and invert arch are compressive in the fault zone near the hanging wall and tensile near the football. Among the several key parts, there are longitudinal tensile and compressive extremes in the arch crown (560 \(\mu\varepsilon\) in tensile and 1220 \(\mu\varepsilon\) in compressive), followed by the invert arch (320 \(\mu\varepsilon\) in tensile and 980 \(\mu\varepsilon\) in compressive), and there is not much difference in the strain extremes of the arch haunch, arch sidewall, and arch springing. Figure 7(c) gives the specific value distribution of shear strain at the arch haunch, arch springing, and arch springing. It can be obtained that the fluctuation range of lining shear strain in the three parts is mainly concentrated at 75 m near the misalignment zone, i.e., the lining is obviously influenced by shear stress in this range, and the maximum values of shear strain are close to the fault zone. The maximum shear strain is found at arch springing (9380 \(\mu\varepsilon\)), the minimum at arch haunch (1910 \(\mu\varepsilon\)), and at the invert arch (7790 \(\mu\varepsilon\)).