In 1947, in Ireland, 150 men began digging a tunnel, through solid granite, two and a half miles long, 800 metres under the Mountains of Mourne. Starting from each side of the mountain, with only candles and string, four years later the two teams met in the middle only inches out of line.
Oh, I forgot to mention they also had explosives, and this was the trick.
Now tunnelling with explosives is not a simple process, it’s not just a case of stuffing a stick dynamite in a crack, lighting the fuse and running away, as many a Western or James Bond movie would have us believe. Oh no.
First you’ve got to drill holes. Again this ain’t about setting the Black and Decker to hammer and getting it in the ear from your mum for all the dust on the carpet. These holes are nine feet deep. So you drill a series of holes in concentric circles, pack the explosives down the end of the holes and wad the whole thing up tight.
The charges are detonated in sequence a few seconds apart. The first explosion is the Burn Cut, a ring of holes in the centre which smashes up the rock and creates a space for the rest of the rock to fall into. Then the Shoulder Holes and Side Holes are detonated to ease the rock away and finally the Floor Lifters to, well, lift the rock off the floor.
Warning; DON’T TRY THIS AT HOME
1 comment:
Judging by the cracks in the walls, somebody HAS already tried this in our house.
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