In order to prevent water leakage into tunnels and rock caverns when these are built, as well as to maintain groundwater levels in the surroundings, pre-injection (pre-grouting) and, if necessary, post-injection* (post-grouting) take place. The pre-injection involves drilling approximately 20-25 meter long holes diagonally forward in the rock in a circle around the future tunnel profile, after which a mixture of cement and water is pressed under high pressure into the boreholes and further out into the rock's natural cracks. When the cement hardens, the rock is sealed around the future tunnel.
In order to be able to pump the cement mixture into the boreholes and the cracks in the rock, the boreholes must be plugged again so that a high pressure can build up and this is done by putting a so-called Packer in the borehole and expanding it so that it becomes tight. This packer must in most cases be attached to an Injection Pipe to be tensioned and for the cement mixture to be pumped in.
This equipment, packers and injection pipes, and related accessories, are developed, manufactured and sold by GMA AB. Packers and injection pipes are available in a variety of variations and designs as shown under the Injection section (scroll down).
If you want to know more about Injection, please watch the video below. There is also a downloadable flow chart which can be helpful when choosing the type of packers and model of injection pipe/hose.
Lastly, you do find more information in our brochure: "Grouting equipment for proffesional sealing" that you can download below, or use the link here to a scrollable version of it.
*Post-injection takes place in the same way as pre-injection, but with the difference that then the holes are drilled in and injection takes place after the tunnel/rock cavern profile has been mined, not in advance.
