Friday, February 19, 2010
Our new tunnel will shorten our drive down the river to Gotsu by a little more than 200 meters. Being straight the tunnel will also be more fuel efficient to drive. A rough calculation says that with present traffic density the fuel savings will have paid for the tunnel in only a few million years. Incidentally, that is my village to the left of the tunnel.
This is the machine that actually drills its way through the mountain. I was expecting to see a huge machine almost as big as the tunnel.... watched too many movies I guess! These smaller drill splay out at any angle.
The next stage is to put up steel arches and then a series of steel beams are driven into the mountain radiating out from the tunnel. Then the tunnel is coated in a thin layer of concrete.
The purpose of the steel beams is to stop the tunnel collapsing under the weight of the mountain, represented here in this demonstration by steel nuts.
Next a thick, waterproof, plastic membrane covers the inside of the tunnel followed by a frame of reinforcing rebar,
The final stage involves this huge machine on rails which is a movable form. Its used to pour the final inner walls of the tunnel.