# Investigation on Vibration Influence Law of Double-Shield TBM Tunnel Construction
## 5 Research on Vibration Influence Range of Double-Shield TBM Construction
### Vibration Influence Range of Double-Shield TBM Construction  
In this paper, the vibration influence range generated by the double-shield TBM construction is studied by taking vibration on human comfort in surface buildings as an index. According to the Technical Standard for Human Comfort of the Floor Vibration (JGJ/T 441-2019) in China [34], the impact of vibration on human comfort is mainly considered in the Z-direction. Based on walking excitation, the peak acceleration of a floor structure, such as an operating room in a hospital, cannot exceed 25 mm/s\({}^{2}\). The peak acceleration of residential houses, office buildings, classrooms, hotels, etc., cannot exceed 50 mm/s\({}^{2}\). Moreover, the peak acceleration limit of shopping malls, cinemas, restaurants, etc., is 150 mm/s\({}^{2}\).  
Therefore, the peak accelerations in the Z-direction of measuring points at a 0-m depth are selected to study the transverse influence range of vibration acceleration. About the longitudinal influence range, taking the maximum peak acceleration in the Z-direction of surface measuring point Z-301 as the object, the relationship between the peak acceleration and the distance from the cutter-head to the monitoring section is analyzed. We can obtain a transverse and longitudinal influence range of peak acceleration, as shown in Figure 11a,b.  
Figure 11: Vibration influence range of double-shield TBM construction. (**a**) Transverse influence range; (**b**) Longitudinal influence range.  
As is shown in Figure 11a, in terms of the transverse influence range, the special sensitive areas with lower-specified vibration limits, such as hospital operating rooms, will be affected by the double-shield TBM construction, which is within 17 m from the tunnel axis. For residential houses, office buildings, classrooms, hotels, etc., human comfort in buildings within 10 m of the tunnel axis is affected. If it exceeds 10 m, the vibration that people can perceive is weak, and it can be considered that human comfort is not affected by TBM construction. In addition, the maximum peak acceleration generated by TBM construction in the \(Z\)-direction on the surface is 120.62 mm/s\({}^{2}\), as shown in Figure 11a. It does not exceed the limits of human comfort within shopping malls, cinemas, restaurants, etc. Therefore, we believe that human comfort is not affected in these buildings.  
We can see from Figure 11b that the peak acceleration begins to exceed 25 mm/s\({}^{2}\) when the cutter-head reaches 38 m before the monitoring section. Similarly, when the cutter-head reaches 29 m before the monitoring section, the peak acceleration exceeds limits for residential houses, office buildings, classrooms, hotels, etc. From the maximum peak acceleration, it does not exceed the peak acceleration limit of 150 mm/s\({}^{2}\). This means that in the longitudinal range, the double-shield TBM construction will not have an impact on human comfort in shopping malls, cinemas, restaurants, etc. After the double-shield TBM passes through the monitoring section by 8 m, the peak acceleration drops to 50 mm/s\({}^{2}\). Subsequently, the peak acceleration drops to 25 mm/s\({}^{2}\) after passing through the monitoring section by 10 m. The vibration influence range of the double-shield TBM construction is shown in Table 5.  
That is to say, the vibration influence range of double-shield TBM construction in hospital operating rooms is 38 m in front of the cutter-head, 10 m behind the cutter-head, and 17 m on both sides of the tunnel's axis. For residential houses and office buildings, the vibration influence range is 29 m in front of the cutter-head, 8 m behind the cutter-head, and 10 m on both sides of the tunnel's axis. Furthermore, the vibration generated by double-shield TBM construction has no effect on human comfort in shopping malls, cinemas, restaurants, etc.