Wednesday, April 25, 2007

Open-cut & Bottom-up Secant Walls, Brooklyn Style.

The Brooklyn Engineering Design and Build question of the day. Concerning our beloved Armory Plaza; "What is the construction sequence when building a secant piling wall foundation using the "Open-cut and Bottom-up method and how is or isn't it being applied in this specific case?" You can Email your answers to: Members of the NYC Forensic Engineering Unit of the Buildings Department are encouraged to submit their answers as well. All answers will be published at a later date.

Lesson of the day.

Using these excellent graphics, (courtesy of Singapore's Land Transport Authority L.T.A.) we can see exactly the steps involved when using the "open-cut and bottom-up" excavation techniques. Before we begin I would just like to mention that these techniques were used, for example, in the construction of Singapore's Rapid Transit Systems Northeast Line or (NEL).
"Construction of NEL spanned six years, from 1997 to 2002. During this period, LTA overcame many challenges. It constructed stations in heavily built-up areas like Chinatown, safeguarded some of Singapore's oldest buildings along Race Course Road - under which tunnelling works were carried out, and executed complex traffic diversion plans along the heavily used northeast corridor."

Sounds a little like bragging to me.

But, I'm getting ahead of myself. Please keep in mind before attempting to make any comparisons, that building a simple subway tunnel is no where near as challenging an engineering feat as say, building The Armory Plaza- a complex five story condo with parking garage in NYC. This is Brooklyn USA after all. Not some muggy provincial, backwater town in some Far Eastern corner of the equatorial third world.
Well then, let's plug in the opaque projector, take our seats and turn out those lights. Can someone get the window blinds please? Thank you Mr. Barbarino.

HINT: The six stages of construction

• Denial and isolation: "This is not happening to me."

• Anger: "How dare God do this to me."

• Bargaining: "Just let my house stand long enough to see my son graduate."

• Depression: "I can't bear to face going through this, putting my family through this."

. Anger again: "Why won't Allstate cover these damages?" "How much does the lawyer want?"

• Acceptance: Bend over and grab your ankles. "I'm ready, I don't want to struggle anymore."

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