tunnels and galleries

The following method can be used to extend the sides of a tunnel:

First, the outer shell of the rock face must be “ripped” by drilling holes lopsided, rather than at right angles to
the tunnel wall. This situation is one of the few exceptions where the holes are made at an angle other than 90º.

The set of wedges is inserted into the hole in such a way that
the break is oriented towards the free face, that is, towards the interior of the
tunnel.

After a few puncture and tear tests, it was soon
You will see how many holes are needed, where they need to be drilled, and how the break can be done to get the best result.