Grouting Tunnels and Penstocks

The main purpose of grouting in tunnel construction is to prevent water inflow at the shaft and to strengthen and solidify the ring shape of the tunnel by stabilizing the material above and behind the concrete rings of the tunnel. The grouting method and technique varies according to the structure of the tunnel, the soil and other material surrounding and supporting the tunnel. In the case of shallow tunnels, the majority of grouting works takes place from the ground surface as opposed to deep tunnels where grouting is performed from the inside of the tunnel. As a result, different patterns of grout are established for both cases. However, when grouting is to be performed inside the tunnel, additional safety measurements and precautions are considered primarily due to zone conflict with other running activities. These activities include water blasting, lining and installing concrete rings.

PCiRoads focuses on safety assessment of tunnel grouting. The basic operations depend on four main factors:

1. Machine and equipment: Site conditions including accessibility and material type are key factors in determining the types machine and equipment employed.
2. Grouting materials: The grout material contains chemical products that are classified as toxic or hazardous that can adversely affect workers' general health. These materials should be handled with special care.
3. Grout location: Grout holes can be drilled from the inside or outside of the tunnel. However, grouting from the inside of the tunnel requires more movement restriction and tighter health considerations.
4. Housekeeping: Housekeeping is required to maintain a safe and clean environment for the workers. In so doing, the number of enabling or triggering causes can be reduced.