# Investigation on Vibration Influence Law of Double-Shield TBM Tunnel Construction
## 5 Research on Vibration Influence Range of Double-Shield TBM Construction
### The Longitudinal Vibration Trend of Double-Shield TBM Construction  
To study the vibration influence trend caused by double-shield TBM construction in the longitudinal section, the peak accelerations with a distance of \(-60\), \(-50\), \(-40\), \(-30\), \(-20\), \(-10\), \(0\), and \(10\) m from the TBM cutter-head to the monitoring section are obtained. It should be pointed out that the distance that the cutter-head does not reach in the monitoring section is negative, and where the cutter-head passes through in the monitoring section is positive. As mentioned before, this paper studies the vibration acceleration generated by the right tunnel's construction, and sampling hole Z-4 is located on the axis of the right tunnel. What is more, it is the closest sampling hole to the cutter-head on the monitoring section. Therefore, we select sampling hole Z-4 as a representative to study the longitudinal vibration trend of double-shield TBM construction. Table 4 presents the peak accelerations of sampling hole Z-4 with different longitudinal distances. As seen from the above table, the maximum peak acceleration in the X-direction occurs at a depth of \(10\) m when the cutter-head is \(0\) m away from the monitoring section; the maximum peak acceleration is \(167.80\) mm/s\({}^{2}\). At the same time, the maximum peak acceleration in the Y-direction also reaches the maximum value at this measuring point, the value of which is \(122.97\) mm/s\({}^{2}\). Unlike this, in the Z-direction, the maximum peak acceleration is located at a depth of \(20\) m, in the measuring point that is the closest to the cutting face. Comparing the monitoring results at different distances, we can see that the maximum peak acceleration of all the measuring points occurs at \(0\) m, regardless of the burial depth and direction. That is, when the double-shield TBM cutter-head crosses the monitoring section, the vibration peak accelerations reach maximum values. After the cutter-head passes through the monitoring section, the peak acceleration decreases rapidly. The reason is that there is a cavity between the double-shield TBM and the surrounding rock, which has a shock absorption effect to a certain extent. The vibration monitoring results of different longitudinal distances from the cutter-head to the monitoring section are arranged according to the buried depth, as shown in Figure 10 below. According to Figure 10a, we can obtain that the peak acceleration increases first and then decreases over the period when the cutter-head is \(60\) m away from the monitoring section to \(10\) m passing through the monitoring section. Among them, the peak acceleration reaches the maximum when the cutter-head reaches the monitoring section. After passing through the monitoring section, the acceleration peak decreases rapidly. It is worth noting that we can also get this rule from Figure 10b,c. The reason is that after the double-shield TBM passes through the monitoring section, there is a cavity between the TBM shield and the surrounding rock, which plays a certain role in shock absorption. What is more, the increase in peak acceleration is generally small when the distance between the cutter-head