London Crossrail Project at ENR.
Press Releases
Nicholson Awarded a Contract on the MTA’s Second Avenue Subway Project
PITTSBURGH, PA – January 18, 2010 – Nicholson was recently awarded a subcontract by E.E. Cruz and Tully Construction Co., a Joint Venture that includes approximately 200,000 SF of diaphragm walls for the construction of the 96th Street station box as part of New York City’s Second Avenue Subway project. Nicholson’s contract also includes jet grouting for a subgrade strut, water cutoff, and temporary support of excavation; compensation grouting for two buildings at excavations for ancillary structures; micropiles within an existing building; and curtain grouting in rock. The project owner is the Metropolitan Transit Authority. [Editor] Click through for the entire press release from GeoPrac.net sponsor Nicholson Construction. [/Editor] […]
Failures
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)
Project Related
The Claremont Tunnel – Designed to Survive Fault Rupture on the Hayward Fault
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 you’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).