how to do contact grouting in tunnel  - a complete process
Channel: Pusker
Date: 2021-01-01

Contact grouting is the process of injecting grout into voids between a tunnel liner and surrounding rock, within the process additonal consolidation of the rock formations is also achieved.Contact grouting involves the filling of void space between a cast-in-place (CIP) structure and the in-situ geo-material or another structure. It may be similar to annular space grouting, however, when contact grouting, normally the extent of the void space is not known. Generally, the intent of contact grouting is to increase the structural integrity of the structure. Contact grouting is often done in association with CIP liners for tunnels, shafts, mine plugs, etc.

Contact grouting may be necessary for numerous reasons, but the primary function is to ensure intimate contact of a CIP structure and the host material. Examples of where contact grouting may be used include the following:

Within pressure tunnels to prevent expansion of the tunnel liner under pressure
Around bulkheads and mine plugs to ensure contact with the surrounding rock
To ensure a minimum thickness of liner is achieved in any cast in place liner system
Within sewer tunnels to prevent sulfate attack of concrete liners from behind the liner
The term contact grouting does not define the type of grout used. Many contact grouting programs are accomplished using ordinary Portland cement grouts; however, based on the void characteristics and the intent of the grouting program, microfine cements or chemical grouts may be utilized.