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RE: Using shoring as structural member

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Greg,

The runoff is collected in ponds.  And trucked off when the project is
complete.

The secant wall or tangent walls can be cantilevered or they can be tied
back just like a sheet pile wall.

The brochure from Intrusion Prepakt has a good picture of a tangent augered
cast pile wall.  The system is similar for a caisson wall.

Regards,
Harold Sprague


-----Original Message-----
From: Greg Leyh [mailto:lod(--nospam--at)pacbell.net]
Sent: Saturday, February 20, 1999 2:30 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Using shoring as structural member


Harold Sprague wrote:

[snip]
>Another consideration for the elimination of tiebacks might be a
>cantilevered wall such as a slurry wall, tangent wall, or a secant pile
>wall.  These walls are top installed.  Once they are installed you excavate
>without having to install lagging or tiebacks.
>
>Tangent walls are constructed by drilling caissons or auger cast piles at a
>given spacing and then installing caissons or auger cast piles in between
to
>seal off the excavation.  
>
>The secant wall is similar except the first caissons are placed and the
>infill caissons actually cut into the prior installed spaced caissons.  The
>first caissons are placed with no rebar.
>
>I have done walls as tall as 30 feet with no tiebacks using a tangent wall.
>
>Slurry walls are another possibility or slurried precast walls.  Sometimes
>the traditional shores, whalers, lagging, cribbing and tiebacks are more
>expensive.

The lot is uphill from the street and quite steep, between 1:1 and 2:1,
so placing drilling equipment may be difficult.  I was curious about how
the runoff on a slurry wall is policed; the city probably wouldn't want
all that bentonite going into the storm drain.  
How is a tangent wall or a secant pile wall normally supported?  
Does it act as a sheet pile wall as it is unearthed?
-- 


-GL
www.lod.org