Grouting is performed using a dedicated integrated grout preparation and injection machine. The grouting material features micro-expansion, high fluidity, early strength, no bleeding, and extended operability. It not only fills voids but also compensates for or repairs defects in the secondary lining concrete, thereby enhancing the overall quality of the lining concrete.

II. Characteristics of the Tunnel Arch Crown Grouting Process with Formwork:

1. The top of the secondary lining formwork is pre-embedded with grouting pipes and grout vent holes, which also serve as inspection holes to check the fullness of the arch crown concrete.

2. The grouting equipment includes WX-RPC grouting pipes (hereinafter referred to as RPC pipes), micro-expansion slow-setting early-strength filling mortar, and an integrated grout preparation and injection machine. The equipment is simple, easy to move, and operate.

3. The operation is straightforward; grouting for one section of the secondary lining takes only about 2 hours and does not interfere with the normal secondary lining construction schedule.

4. Grouting with formwork can begin when the concrete initially sets. The grouting pressure is significantly higher than that applied after formwork removal, improving the integrity between the lining concrete and the grout, and repairing various concrete defects.

5. During grouting with formwork, the secondary lining concrete is protected by the trolley formwork and remains undamaged. Typically, the concrete pouring pressure exceeds 6 MPa, while the grouting pressure generally does not exceed 1.0 MPa.

III. Key Points of the Tunnel Arch Crown Grouting Process with Formwork:

1. The construction process involves pre-embedding radial grouting pipes in the trolley. Grouting is performed through these pipes promptly 2 hours after the secondary lining construction is completed. The operation can be carried out using a dedicated integrated grout preparation and injection machine. The grouting material exhibits micro-expansion, high fluidity, early strength, no bleeding, and slow-setting properties. It not only serves to fill voids but also compensates for or repairs defects in the secondary lining concrete.