# Structural Stress Characteristics and Joint Deformation of Shield Tunnels Crossing Active Faults
## 3 Analysis of Segmental Tunnel Influenced by Fault Movement
### Deformation of Segmental Lining and Joints  
Figure 14 illustrates the longitudinal and circumferential joint deformation of the segmental tunnel subjected to normal faulting. As can be seen, under normal fault displacement, the maximum deformation of longitudinal joints was located at the tunnel vault. When fault dislocation of 15 cm was imposed, the maximum opening of the longitudinal joints was 2.01 mm. The maximum deformation of the circumferential joints was located at the arch haunch, and when the fault dislocation reached 15 cm, the maximum opening of the circumferential joints was 6.82 mm. Because the deformation of the longitudinal joints was much smaller than that of the circumferential joints, it can be considered that, in the normal faulting cases, circumferential joint deformation is dominant in segmental joint deformation.  
Figure 14: Deformation of segment joints under normal fault dislocation. (**a**) Deformation of longitudinal joints and (**b**) deformation of circumferential joints.  
Figure 13: Stress of joint bolts subjected to reverse fault displacement. (**a**) Stress of circumferential bolts and (**b**) stress of circumferential bolts. Some like +4.447e+08 means 4.447 \(\times\) 10\({}^{8}\).  
The deformation of the segmental joints under reverse faulting is presented in Figure 15. It can be observed that, under the reverse fault dislocation, the maximum deformation of the longitudinal joints was at the arch haunch. When the fault displacement reached 20 cm, the maximum opening of the longitudinal joints was 1.1 m. When the fault displacement was 20 cm, the maximum opening of the circumferential joints was 0.84 mm, and the maximum deformation of the circumferential joints was located at the tunnel vault. Although the deformation of the longitudinal joints was slightly smaller than that of the circumferential joints, the deformation of both was small. It can be considered that the circumferential and longitudinal joints are not prone to large deformation under the reverse fault displacement condition.  
The lateral convergence deformation of the segmental lining subjected to fault dislocation is illustrated in Figure 16. The lateral convergence deformation of the segmental lining was significantly affected by the fault dislocation, and the maximum lateral convergence deformation of the tunnel segment was located near the projection surface of the top of the fault. When normal faulting of 15 cm was imposed, the maximum lateral convergence deformation of the segmental lining was 38.9 mm. However, when the reverse fault displacement of 20 cm was imposed, the maximum lateral convergence deformation of the tunnel segments was merely 26.5 mm, which implies that the maximum lateral convergence of the tunnel segments subjected to the normal fault dislocation is much larger than that under the reverse fault dislocation condition.  
Although the segmental tunnel was mainly subjected to lateral force under reverse fault movement, the overall longitudinal compression state of the tunnel increased the capability of the tunnel structure to resist lateral deformation. Although the lateral convergence deformation of the segmental lining was relatively smaller than that of the normal fault dislocation, the concrete structure caused lateral crushing failure when the reverse fault displacement reached 20 cm.  
Figure 16: Transverse convergence deformation of a shield tunnel under faulting: (**a**) normal faulting condition and (**b**) reverse faulting condition.  
Figure 15: Deformation of segment joints subjected to reverse faulting. (**a**) Deformation of longitudinal joints and (**b**) deformation of -circumferential joints.