A stretch of tunnel on Eastbound I-70 in scenic Glenwood Canyon Colorado was closed last March because of a 70-foot long crack in the ceiling. Since then the two-lane westbound bore has been handling both eastbound and westbound traffic while repairs to the damaged segment were undertaken. This project has a little of everything: heavy excavation, rockfall, slab reinforcing, geofoam, and even geogrid! Read on for more details, a map and photos. (Photo by Concrete Works Of Colorado)
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)
The Claremont tunnel beneath the Berkeley Hills on the east side of Oakland is a water supply tunnel that serves over 800,000 customers in Richmond, Oakland, San Leandro and neighboring communities. One of the unique things about the tunnel is that it crosses the active Hayward Fault. Most of the time when you talk about designing for earthquakes youâ€™re talking about designing to withstand the seismic forces. In this case, the designers needed the water transmission tunnel to withstand up to 7.5-ft of offset due to fault slip and still maintain a minimum level of service. (Photo credit: Sue Bednarz, Jacobs Associates, Inc. by way of Civil Engineering Magazine)
This post describes the relatively recent Claremont Tunnel Seismic Upgrade Project as reported in Civil Engineering Magazine (May 2008, v. 78, no. 5, pp 58-63, 96-97).