# Model Test Study on a Shield Tunnel Adjacent to Pile in the Sub-Clay of a Coastal Area
## 4 Test Results
### Model of the Zonal Blockization of Surrounding Rock  
Combined with the influence of shielding on the deformation and stress field of the weak surrounding rock, the bending moment and displacement of the adjacent pile were analyzed. The zonal block model of the shallow tunnel surrounding rock had a regional division, which is shown in Figure 27.  
The weak surrounding area around the pile side was divided into five parts: the coordinated movement of surrounding rock and pile in zone I was the most intense, with the largest settlement and horizontal displacement. Safety construction measures such as reinforcement and underpinning piles to prevent over-settlement of buildings and structures in this area should be taken. It is recommended that the short piles in this area should be densely distributed. Zone III will be affected by shielding construction, but generally it would not pose a great threat to the normal use and the safety of buildings and  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**H/D**} & \multicolumn{2}{c}{**Horizontal**} & \multicolumn{2}{c}{**Vertical**} \\ \cline{2-5}  & **2D\(\rightarrow\)1D** & **2D\(\rightarrow\)3D** & **0.5D\(\rightarrow\)0D** & **-0.5D\(\rightarrow\)0.5D** \\ \hline
1 & 40.10 & 14.79 & 4.41 & 19.55 \\
2 & 39.62 & 12.34 & 6.16 & 19.78 \\
3 & 42.09 & 14.23 & 6.42 & 19.32 \\ \hline \hline \end{tabular}
\end{table}
Table 12: The reduction percent of horizontal displacement at different position of pile (%).  
Figure 27: Region division of rock with pile when shield.  
structures. Real-time monitoring should be carried out during construction. If piles were driven in this area, it is recommended to use sparse piles and keep them deeply buried. engineering accidents such as pile over-displacement or inclination are expected. When the shield jacking force acts on the tunnel face, the jacking can easily cause the pile to bend back or forth along the jacking direction, and the pressure change in shield tail grouting can cause the pile to bend left or right perpendicular to the tunnel axis. In the actual shield construction process, isolation and reinforcement measurements should be constructed to prevent the pile from excessive settlement and inclination and prevent the internal force and deformation of the pile from reaching a limited state. The settlement of piles in Zone IV was small, but due to the stress release of surrounding rock near the arched camber line, the piles bear negative bending moments. The uneven stress effect of the piles would pose a threat due to different shield friction and grouting parameters at the same time. The main factors considered in this area were the limit state of the normal use of piles and the according safety issues. This area could be considered the best zone for an isolation pile driving area. Zone V could be considered as the safe area for the pile-shielding system. Shield excavation has little impact on these surrounding layers, which neither cause the large displacement nor the ultimate bending moment of the pile.  
Similar conclusions or laws can be compared according to the references [15; 16; 17; 18].