# Key Technology of TBM Excavation in Soft and Broken Surrounding Rock
## Appendix C Verification of matching relationship between blade spacing and vertical force
### Grouting Equipment
#### 4.4.2 Advanced Grouting Reinforcement Method for Non-Expanding Excavation Pipe Shed  
Starting Conditions  
TBM is tunneling in soft and broken stratum. When TBM is difficult to drive but the machine is not jammed, the nonexpanding pipe shed grouting advance reinforcement method can be used to treat the soft and broken stratum without excavating a small pilot tunnel. Generally, the nonexpanding pipe shed grouting advance reinforcement method is started when RQD < 40. This method reduces the downtime of TBM and improves the tunneling efficiency. Figure 19: Chemical grouting equipment. Figure 18: Schematic and physical drawing of steel grouting pipe. Pipe Shed Materials and Equipment  
The diameter of the pipe shed is \(\oslash\)76, and the pipe shed is divided into sections with a length of 1.5 m, which are connected and lengthened by threading. The joints of adjacent pipe sheds are staggered. A 3 m slurry stop section is set at the end of the pipe shed. The slurry overflow holes of the pipe shed are arranged in a quincunx pattern, with a row spacing of 50 cm and a hole diameter of 6-8 mm. The drilling rig can be equipped with an Atlas 1838 drilling rig. The main tunnel TBM is installed on the track of the special advance drilling rig, and the horizontal guide TBM is installed on the temporary support, as shown in Figure 21.  
Pipe Shed Construction  
An advance pipe shed shall be constructed to pre-reinforce the surrounding rock in front of the tunnel. The pipe shed passes through the reserved hole of the steel arch. After  
Figure 21: Pipe shed construction equipment. Figure 20: Strengthening effect of chemical grouting on broken surrounding rock. the drilling is completed, withdraw the drill pipe and observe whether the hole is complete and installed \(\oslash\)76 conditions of pipe shed if it cannot be constructed. For the pipe shed, the drill pipe of the drilling rig shall be used as the leading pipe shed. The specific operation steps are to drill the hole to the set depth before exiting the drill pipe, and after the slurry overflow hole is processed on the drill pipe, the drill pipe shall be driven again to serve as the leading pipe shed. The length of the pipe shed is 15-25 m, which is determined according to the degree of surrounding rock fragmentation. The drilling rig can be used as the minimum insertion angle. Pipe sheds are set obliquely forward through the tail of the shield according to the circumferential spacing of 0.4 m (the spacing is adjusted appropriately according to the drilling conditions). The setting range is 90\({}^{\circ}\) of the arch; there are 14 pipe sheds in each ring. The schematic diagram of the pipe shed setting is shown in Figure 22, and the pipe shed shooting site is shown in Figure 22. During the construction of the advanced pipe shed, the method of the jumping sequence shall be adopted for setting. The odd-numbered holes shall be marked first, and then the even-numbered holes shall be marked. The grouting materials used for the advanced reinforcement of the surrounding pipe shed include cement double-liquid slurry and polyurethane chemical slurry. When the drilling depth of the pipe shed is less than 15 m, polyurethane chemical slurry is generally used to prevent the slurry from flowing and causing the shield to be solidified. When the drilling depth of the pipe shed is more than 15 m, double-cement slurry shall be used. In addition, when the water yield of surrounding rock is large and water plugging is required, polyurethane chemical slurry is used. The grouting completion standard is determined by the combination of constant pressure and quantitative. The constant pressure standard is designed according to the geological conditions, the final grouting pressure is 1.5-3 MPa (which can be adjusted according to the grouting situation on site). The single hole grouting pressure reaches 3 MPa. The quantitative standard is determined according to the porosity of the stratum, the geological conditions, and the slurry absorption of the stratum.