USING GROUTING WHEN TUNNELLING

Grouting is used to assist tunnelling or mining by reducing water inflow or strengthening the foundation ahead of a drive. An example is shown below where a ring of grout holes is used for grouting the area about to be excavated.

This tunnel or mine drive is advancing from the left. Before it can safely proceed grouting is needed to strengthen the rock ahead so that it will not collapse when excavated,....or maybe grouting is needed to reduce excessive quantities of groundwater inflow.

Start Over

If the excavation is carried out by blasting this can loosen the grouted area; the grouting may then have to be repeated in bad areas.

...AND SOME OTHER USAGES

Grouting can assist when

• sinking shafts
• filling voids behind tunnel liners
• filling gaps at contraction joints in massive concrete structures
• strengthening foundations, raising settled structures, etc by use of 'compaction grout'
• making concrete by the intrusion process where the coarse aggregate is placed in position and a sand grout is then injected through it.

And there are many other lesser known usages. For full treatment of all the types of grouting consult PRACTICAL HANDBOOK OF GROUTING by James Warner.