# Analysis of Shield Tunnels Undercrossing an Existing Building and Tunnel Reinforcement Measures
## 7 Deep Hole Grouting Reinforcement Technology for Shield Tunnel
### Effect of Radius of Radial Reinforcement on Reinforcement Effect of Deep Hole Grouting in Tunnel
Therefore, if the deep hole grouting reinforcement measures were taken in this project to reduce the impact of the excavation of shield tunnels on the building and piles, the radius of radial grouting reinforcement can be set to 2 m or 3 m, which was similar to the conclusion in reference [35]. Figure 31: Relation between the lateral displacement of pile and the radius of grouting reinforcement. Figure 30: Relation between the subsidence of building and the radius of grouting reinforcement. Effect of the Reinforcement Range before and after the Building on the Reinforcement Effect of Deep Hole Gruting in Tunnel  
The reinforcement range before and after the building referred to the surrounding soil of the segments participating in the deep hole grouting reinforcement in the front and rear of the building. As analyzed above, in this section, the surrounding soil was grouted and reinforced after the segments came out of the five rings at the tail of the shield. The grouting pressure was set to 250 kPa, and the excavation pressure was still set to 200 kPa, the jack pressure was still set to 150 kPa. The slurry solidified and hardened after five rings of grouting. The radius of grouting reinforcement was taken as 3 m. The soil within the range of rings of 0, 2, 4, 6, and 8 in front and behind the building was reinforced. The ring of 0 was only used to reinforce the soil around the segments under the building. During the shield tunneling process, the maximum subsidence of the building and the maximum lateral displacement of the pile with the excavation of the shield tunnels under different reinforcement ranges were shown in Figures 33 and 34, respectively. Figure 35 shows the histogram of the maximum subsidence of the building and the maximum lateral displacement of the pile under the different reinforcement ranges during shield tunneling. Figure 33: Relation between the subsidence of building and reinforcement range before and after the building. Figure 32: Maximum subsidence of building and maximum lateral displacement of pile under different reinforcement radii. From Figure 33, it can be found that the variety rule of the subsidence of building with different reinforcement ranges was basically the same during the process of shield tunneling. Compared with no grouting reinforcement measures, the use of grouting reinforcement measures for deep holes in the tunnels can evidently abate the subsidence of the building. When the reinforcement range was 0-6 rings, the subsidence of the building reduced with the increase of the reinforcement range, while the building subsidence increased when the reinforcement range increased to eight rings. Figure 35 shows that the maximum subsidence of the building was 7.37 mm without grouting reinforcement, while the maximum subsidence of the building was 4.59 mm for the reinforcement range of 6 rings, with a reduction of 37.72%. From Figure 34, it can be found that the variety rule of the lateral displacement of the pile with the different reinforcement ranges was basically the same during the process of shield tunneling. Compared with no grouting reinforcement measures, the use of grouting reinforcement measures for deep holes in the tunnels can evidently abate the lateral displacement of the pile. When the reinforcement range was approximately zero to six rings, with an increase in the reinforcement range, the pile's lateral displacement increased, while the lateral displacement of the pile reduced when the reinforcement range was eight rings. Figure 35 shows that the maximum lateral displacement of the pile was 3.83 mm without grouting reinforcement, while the maximum maximum  
Figure 34: Relation between the lateral displacement of pile and reinforcement range before and after building. Figure 35: Maximum subsidence of building and lateral displacement of pile under different reinforcement ranges. lateral displacement of 2.18 mm of the pile was the minimum for the reinforcement range of zero rings, with a reduction of 43.08%.