# Synchronous Grouting Analysis of Shield Tunneling through High Water Pressure Fault Fracture Zone
## 2 Fault Fracture Zone Model
### Establishment of Fault Fracture Zone Model  
Due to the formation process of fault fracture zones leading to their structural diversity, in order to better study the synchronous grouting law of fault fracture zone strata, the fault fracture zone structure adopts a symmetrical and complete structure, including upper and lower wall induced crack zones and sliding fracture zones. A three-dimensional numerical model of shield tunneling machine passing through the complete fault fracture zone is established. At the same time, it is assumed that the calculation domain of the strata is symmetrical about the tunnel axis, and half of the strata are taken for modeling and calculation. Based on the study of the B3 section of the Pearl River Delta Water Resource Allocation Project, the water conveyance tunnel in this section runs from Dongyong Town to Shatian Town, Dongguan City. Two shield tunneling machines are used to enter Haiou Island 6 well in Panyu District, Guangzhou from Shagongbao location 5 to the east, and from Shatian Town 7 underground to Haiou Island 6 well, forming a single line shield tunnel with a total length of approximately 6.62 km. Using on-site shield machine data, as shown in Table 2. According to the Saint Venant principle and boundary effects, the following issues should be noted: \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Location** & **Pile Bearing Layer** & **Relativeness** & **Spacing** \\ \hline Hongling Interchange & Moderately weathered granite & Passing through the middle & Plane spacing of 4.3 m and 2.4 m \\ \hline Hongling Ramp Bridge & Moderately weathered granite & Passing through the middle & Plane spacing of 6.6 m and 1.3 m \\ \hline Bao’an Interchange & Strongly weathered fragmented rock & Vertically underpass & Vertical distance 3.7 m \\ \hline Bujie Bridge & Strong–weathered fractured rock & Vertically underpass & Vertical distance 3.8–9.3 m \\ \hline Chunfeng Viaduct & Strongly weathered & Vertically underpass & Vertical distance 8.7–9.0 m \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Underpass situation of Chunfeng Tunnel. (1) The distance from the bottom of the tunnel to the bottom of the soil layer should be controlled at three times the tunnel diameter;  
(2) The width of the soil on the side of the tunnel is generally controlled at six times the tunnel diameter. Therefore, the cross-sectional size of the model is taken as 40 m \(\times\) 56 m \(\times\) 60 m, the distance from the top to the bottom of the model is 60 m, and the buried depth at the top of the tunnel is 25 m. The numerical model is shown in Figure 1. And the schematic diagram of model components is shown in Figure 2.  
(1) Excavation construction simulation method:  
The model is based on the stiffness transfer method and uses the \"Model Change\" command in ABAQUS to kill and activate elements, simulating the excavation of soil by shield tunneling. Each time the shield machine advances a ring (with a width of 1.6 m), a grouting unit is activated behind the shield tail. As the excavation surface advances, the shield machine gradually pushes in and the shield tail gradually pushes out. The shield tunneling is studied as a discontinuous process, and the disturbance changes of soil and water pressure during the excavation process are obtained through finite element calculation. (2) Boundary conditions:  
The axisymmetric plane of the model limits its displacement in the X direction and is set to be impermeable to the water surface; both sides of the soil calculation domain restrict their displacement degrees of freedom perpendicular to the surface, and apply the pore \begin{table}
\begin{tabular}{c c c c} \hline
**Cutter Disc Excavation Diameter** & **Outer Diameter of Pipe Segment** & **Inner Diameter of Pipe Segment** & **Tail Gap of Shield** \\ \hline
8.65 m & 8.3 m & 7.5 m & 0.35 m \\ \hline \end{tabular}
\end{table} 
Table 2: Basic dimensions of tunnel model. Figure 1: Model size diagram. Figure 2: Schematic diagram of model components.