# Synchronous Grouting Analysis of Shield Tunneling through High Water Pressure Fault Fracture Zone
## 2 Fault Fracture Zone Model
### Establishment of Fault Fracture Zone Model
pressure corresponding to the hydrostatic pressure; the groundwater level is located on the surface of the soil layer and the pore water pressure is set to 0; the direction of gravity load is downward along the Z direction. (3) Grouting simulation:  
Existing research has shown that the distribution of grouting pressure is related to the grouting method. This article relies on the shield tunneling machine equipped with six grouting holes. During the construction process, only the upper and middle four grouting holes are often used for simultaneous grouting. According to the on-site measurement of synchronous grouting pressure in the literature, it is shown that the distribution pattern of grouting pressure is mostly small in the upper part and large in the lower part, and the pressure distribution is symmetrical and relatively uniform, as shown in Figure 3. And the model construction load is shown in Figure 4.  
Therefore, this article applies a uniformly distributed grouting pressure on the contact surface between the grouting layer unit and the soil within a range of 3.2 m (2 rings) behind the shield tail, which deviates from the tunnel axis. As the shield tunneling and slurry hardening, the grouting pressure decreases. Considering the self-weight of the slurry, the pressure increases along the depth of 10 kN/m\({}^{3}\), and the same grouting pressure is also applied on the contact surface between the grouting layer and the pipe segment; during synchronous grouting of shield tunneling, pore pressure boundary conditions are applied at the interface between the grouting layer and the soil. According to literature, it takes a  
Figure 4: Model construction load. Figure 3: Actual measurement results of synchronous grouting pipe segment grouting pressure. long time for pore water pressure to dissipate in weakly permeable formations. However, in reality, the pressure of the shield tail slurry will dissipate quickly due to hydration and hardening. Therefore, transient analysis is used in the analysis step to consider the process of pore pressure change. (4) Complete construction steps:  
Firstly, the stress balance of the fault fracture zone model is analyzed to restore the true stress state; in the first analysis step, the element life and death function in ABAQUS is used to remove the excavated soil element at the first ring, simulate shield tunneling, and apply mud pressure and pore pressure boundary to the tunnel face to simulate shield tunneling mud; in the second analysis step, the next ring of soil unit is excavated, and the next ring of shield machine unit is activated. The mud pressure and pore pressure boundary move forward by a distance of one ring and are applied to the position of the palm face during the excavation of the second ring to simulate the propulsion of the second ring of shield machine. When the previous ring of shield machine is removed, the grouting layer unit and segment unit inside the ring are activated to form support. At the same time, radial grouting pressure and pore pressure boundary are applied to the ring to simulate the grouting process at the shield tail, In the subsequent analysis steps, the grouting pressure gradually decreases and the grouting layer material is strengthened to simulate the solidification of the slurry and the dissipation of grouting pressure; in the following analysis steps, repeat the above process to simulate the continuous advancement of the shield machine. In order to simulate the grouting process at the tail of the shield, the shield unit is killed at the initial position, the first ring lining unit and the grouting layer unit are activated, and radial grouting pressure and pore pressure boundary are applied to the grouting layer unit. In the second and third analysis steps, gradually reduce the grouting pressure and pore pressure boundary of the ring, and then strengthen the material modulus of the grouting layer unit to simulate the dissipation of grouting pressure and slurry hardening.