If an underground tunnel needs repair, geotechnical construction techniques often are the best methods to solve those problems. The following are common pressure grouting techniques used in tunnel improvement or repair:
- Cement grouting stabilizes soil beneath or around tunnels to prevent sinking, and also provides support for the creation or drilling of new tunnels.
- Permeation grouting stabilizes soil for settlement control.
- Chemical grouting allow for the groundwater control, preventing unwanted water from leaching in to the tunnel over time.
- Compaction grouting stabilizes potential sinkholes which may impair the integrity of the tunnel.
- Void fill/Cellular grouting provides a cost effective solution to fill voids and decommission tunnels.
- Contact grouting fills voids between concrete linings, cast in place or precast, and the host geological materials. Additionally, it is used to fill similar voids between steel penstock lining backfill concrete and the host rock support.