PIERCING BLAST

[civinco01]

I have a case of a water outfall Tunel in Phillyte rock to be excavated to be able to connect to an existing water outfall tunnel which is generally full of water and cannot be dried due to operatibility of another process. Our consultant is recommending to build a tunnel just 5 meters before connecting to the existing tunnel and then through piercing blast do the rest. If someone could assist me I would like to know:
1- What is a piercing blast?
2- Has anybody had such an experience to connect to an operating tunnel of water that cannot be shut down.

Thanks for your feedback

 

[exploengineer]

This is the same type of blast as shooting a plug from a tunnel to a lake, used when building dams, etc.

I've done a few of them in South America.

Frank Lucca M.I.Exp.E.

http://www.terradinamica.com