Annulus grouting

Annulus grouting in tunnels is the filling of the void that is created between the soil or rock and the segmental lining. In tunnelling it helps stabilise the tunnel and ensure forces are transmitted between the tunnel and surrounding ground evenly. It is required as when a shielded TBM machine cuts into the rock there is a small overcutting so that tunnel segments can be efficiently placed as the machine advances.

Generally, either inert, cementitious or accelerated grouts can be used. Two-component silicate accelerated annulus grouts are mostly used.

Efficient and trouble-free annulus grouting is essential to maximise TBM uptime, reduce settlement risk, fully embed the lining to transmit forces around the ring and, last but not least, protect the lining and gaskets. No matter whether job sites have chosen to use two component mortar or pea gravel grout, Normet can provide guidance and support to reduce the learning curve and build confidence in the team