Thursday, July 7, 2011

Geotechnical: Ottawa Tunnel Going Shallow


Ah, they cheapen the project by going for shallower rock.  And they are relying on boreholes for this.

The only problem is that the vertical fractures have been disturbed by ancient glaciation.  We found that rock can be disturbed up to 60 m deep.  Obviously, there is less of that the deeper you go.  Now, maybe the rock is all gunked up with Leda clay, so that everything is breezin'.  Or maybe there's sand!

I'm making a prediction that shallow isn't cheaper.  But, then, I thought this whole project would be a rock disaster, even at the deeper depths.  Vertical boreholes are a bitch with vertical fractures!  Have fun!  :)

ps. I would be less gloomy with rock stress measurements!

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