It seems like every time I turn around these days there is another amazing tunnel project in the news. The level of engineering brought to bear on these challenges is phenomenal, whether it’s in the tunnel alignment or the TBM design and fabrication, or shoring and ground improvement in advance of the tunneling. This article highlights 7 record-breaking tunnels from around the world. Check back in another year or two and I’m sure there will be some new accomplishments to add to this list! [Source: Check out the Record Breaking Tunnels on Fox News! via ASCE SmartBrief. Image: Fox News]
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Cologne Tunnel Collapse: Investigations Focus on Tiebacks and Groundwater
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)