Leica automated motorized total station excavation support deformations
Project Related

The Cycles of Clough

At last month’s Earth Retention Conference, ER2010, there were many references to the second ER conference in 1990. One paper from that proceedings that garnered many mentions and was referenced by several at this year’s […]

Nicholson Construction Company
Press Releases

Nicholson Awarded Earth Retention Contract for Seattle Light Rail Project

Nicholson Construction CompanyPITTSBURGH, PA – January 15, 2010 – Nicholson was awarded a subcontract by Traylor Bros./Frontier-Kemper JV that includes temporary shoring and the construction of the permanent reinforced concrete diaphragm walls for the a new light rail station near the University of Washington’s Husky Stadium in Seattle. The project owner is Sound Transit and the work will be completed in a joint venture with Condon-Johnson & Associates. [Editor] Click through for the entire press release from GeoPrac.net sponsor Nicholson Construction. [/Editor] […]

Miscellaneous

World Trade Center Slurry Wall to Become Part of Museum

The only portions of the World Trade Center towers that survived the attack on 9/11 were the basement slurry walls, part of the original shoring and foundation system. The National September 11 Memorial and Museum at the World Trade Center that is currently under construction will preserve a portion of that wall making it the largest exhibit the museum will offer. The wall section displayed will be 62-ft by 64-ft.

The existing slurry walls are being incorporated into the foundation system of the new facility but not without some improvements. The are adding some kind of foundations improvements to stabilize the toe of the walls, the New York Times article calls them caissons, but I don’t know if its a tangent or secant wall or something else. They are also lining them with additional concrete and reinforcement in front of the walls along with additional tiebacks to stabilize them. In the portion of the wall that will be displayed, a counterfort wall will be constructed behind it and new tiebacks will be installed on the front. Work for the counterfort wall will be done by hand in order to avoid the existing tieback cables. All of the existing tiebacks will be left intact. Check out the NY Times article for a great graphic showing the system. (Illustration by New York Times)

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Failures

City of Vancouver sues over failed shoring

The City of Vancouver is suing a developer, excavation contractor and their consulting engineer for the costs of repairs, overtime for city employees and lost revenue from parking meters etc stemming from an apparent failure of a shoring system that formed a 30-meter sinkhole. No mention of the developer’s name or the engineer, but the contractor was Matcon Excavation and Shoring. The site will be the future home of high-rise condominiums…if the City lifts it’s stop work order.

The failure of the shoring caused a break inf a 20-cm water main ultimately flooding the site. It also necessitated the closure of the adjacent street. Of course this invites the whole chicken or the egg scenario. The defendants will probably argue that the water line failed first causing the failure of the shoring, but of course the City Engineer, Tom Timm was not shy about fingering the shoring as being deficient.

"It’s some kind of a failure of the shoring system . . . either a design issue or the way it was put in place."

 

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