Curtain grouting: Curtain grouting is mainly used for advanced grouting, so its accurate name is "advanced curtain grouting", which refers to an auxiliary construction measure to comprehensively strengthen (or block water) the soil in a certain range in front of the tunnel and form a waterproof curtain around the excavation area to prevent the leakage of groundwater from bringing greater risks to tunnel construction. -Detailed Rules for the Design of Highway Tunnels

Post-tunnel grouting: Post-tunnel grouting can be divided into two types: secondary lining post-backfill grouting and initial support post-backfill grouting.

Backfilling and grouting after initial support: there is a large area of water leakage on the surface of completed initial support, or there is an impermissible gap between initial support and majesty, which may lead to induced surface settlement, deformation or frost damage. At this time, backfill grouting is carried out behind the initial support.

Backfilling grouting behind the secondary lining: Backfilling grouting is carried out behind the secondary lining to fill the gap between the arch waterproof board and the secondary lining.