This 57-km tunnel under the Swiss Alps has nearly broken through after 11-years of work. This tunnel will create a ‘flat’ rail path through the Alps and become the world’s longest rail tunnel. [Source: World Tunnelling. Image: Alp Transit]
The century-old PATH subway tunnels underneath the Hudson River were not excavated through bedrock, but rather under a thick layer of silt and clay. Apparently there is a a sufficient security concern to warrant protecting […]
The latest information to come out of the collapse of a subway tunnel excavation in Cologne, Germany is that investigators are evaluating the ground anchors or tiebacks that were holding open the subway tunnel excavation. There doesn’t appear to be much information available to the public yet, and the New Civil Engineer article mostly quoted academics saying an anchor failure “could” have caused the collapse. Apparently at the time of the collapse, the excavation had reached the bottom depth after the slurry walls had been constructed along with the ground anchor system. Crews were supposedly working on the base slab which would have undoubtedly stiffened up the whole system. For what its worth, an anonymous comment left at the bottom of that article indicated that after half of the debris had been excavated, the diaphragm walls were still intact and without apparent displacement. So what other theories have been floated? Read on for more info. (Image Credit: New Civil Engineer)
[Updated November 17, 2009] A few new posts from Ontario-geofish [/Updated]
Those with interest in rock mechanics and tunneling might be interested in this project. The Ontario Power Generation (OPG) company is the owner of a $600M (Canadian) construction project to create a third hydro power tunnel under Niagara Falls. Apparently the project is having all kinds of problems with overbreak in some very difficult tunneling conditions which means very slow progress and big $$ overruns. (Photo from niagarafrontier.com)
I’ve been meaning to post something on this project for some time. I admit that my perspective is biased by the viewpoint you can find on the Ontario-geofish blog. I’ve mentioned Harold Asmis before, he’s the owner of the OG blog, and a former OPG employee if I understand correctly. He left OPG for a career doing geophysics and earthquake engineering for the Nuclear Power industry in Canada. I highly recommend his blog, he has great insight into tunneling, earthquakes, siting of nuclear power plants not to mention opinions on all kinds of other things. His writing style is very colorful and entertaining as well.
So, Harold has written a whole series of blog posts on the Niagra Tunnel project, including a 5-part series entitled "The Disaster of the Niagara Tunnel" and a 4-part series called "Niagara Tunnel: doing it Right". He is not directly involved with the project, but his long career with OPG and related disciplines gives him some great insights. I’ve collected a list of some of his blog posts on the Niagara Tunnel project as well as a few other links about the project. Click through for the good stuff.