Work had been disrupted since Sept. 11 when there was a collapse of rock from a 25-metre section of the tunnel's ceiling. It occurred about two kilometres into the tunnel, more than three kilometres behind the spot where the tunnel-boring machine, nicknamed Big Becky, is cutting into the rock face.
This is all from a local news outlet, and is directly from the official mouthpiece. However, we learn that the collapse was much worse than I thought, with 25 m of lining taken out. That must be at least 500 tons of rock! I'd love to know how much extra overbreak there is now! And it's all been fixed with mesh and shotcrete.
We also learn that it completely blocked access to the TBM so I wonder how much 'scheduled maintenance' they got done. As well, we find out the Ministry of Silly Walks and Rock got involved, which is interesting.
So, do we think the tunnel is better off for having barfed up all this rock? Surely we must go with all those silly earthquake scientists who think that once rock fails, it will never fail again? (latest ENA earthquake theory). Sadly, the new configuration with the steep vertical arch is even more unstable under high horizontal compressive stresses. The rock failure will just want to work its way to the surface. And all the other rock will want to join in on the party!
After the rock failure in Scotland, and the recession, I can't believe these guys can get credit, investment, and insurance. Most amazing...
Where are those dang Tunnel News people anyway?