Project Related

Basement Excavation for Seattle High-Rise

Last week I attended the AEG 2013 conference in Seattle, Washington. The conference was excellent, with many great presentations and networking opportunities. I have been playing catch-up since I returned, but I have some very […]


Cologne Tunnel Collapse: Investigations Focus on Tiebacks and Groundwater

image 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)