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 conference as a seminal paper was by Dr. G. Wayne Clough and Thomas D. O’Rourke entitled ‘Construction induced movement of insitu walls‘. I found it somewhat poetic that a recent issue of Geocomp’s newsletter described the monitoring of deformations of the temporary shoring for the Clough Undergraduate Learning Commons at the Georgia Institute of Technology (Georgia Tech). Geocomp performed the monitoring using multiple Leica automated motorized total stations (AMTS) with reflective prism targets along with their iSiteCentral software to ensure no deformation-induced damage to the adjacent historic library structure. [Source: Geocomp Newsletter. Image: Geocomp]
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Theme from ER2010 Day 1 – Advancements in Earth Retention and Future Trends
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)
Shoring retaining wall failure in Virginia prompts apartment building evacuation
On Sunday evening, a soldier pile lagging wall shoring system failed at the Sedona & Slate residential development construction site in Rosslyn, Virginia (Arlington County). There were no reported injuries, but an adjacent apartment building was evacuated as a precaution and a nearby street is closed to traffic. Click through for a video that shows some additional views of the damage. The scale of the wall is apparent when you see the shots with workers putting braces near the bottom of the wall. I’m guessing the rakers shown in this image were added monday to attempt to stabilize the wall, but that’s just speculation at this point. Image: MyFoxDC.com