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Re: "Hydrovac" for pier construction

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Daryl,

It appears that you have designed hydrovac constructed piers. Do you have any insight in to the formulas for determining vertical and lateral load capacities of such piers. Intuitively, these piers should have lower capacities than traditionally drilled peirs.

Rajendran

Daryl Richardson <h.d.richardson(--nospam--at)shaw.ca> wrote:
Gentlemen,
 
        One feature of refinery sites is that the people operating them sometimes loose, misplace, forget or otherwise do not know what underground pipe and electrical lines they may have in the vicinity of pile excavations.  One of the reasons they like to hydravac (the top few feet, if not all of) their pile excavations is that it provides a much lower risk of having an inconvenient, serious, or even catastrophic accident involving buried lines.
 
        Otherwise, auger drilling could be a good idea.
 
Regards,
 
H. Daryl Richardson
 
       
----- Original Message -----
From: Tripp Howard
To: seaint(--nospam--at)seaint.org
Sent: Tuesday, May 23, 2006 3:27 PM
Subject: RE: "Hydrovac" for pier construction

Have you considered using auger cast displacement piles?  Berkel and Morris-Shea Bridge both have a version.  Basically the auger has a blocking section on it that pushes the soil coming up the auger flights out into the surrounding soils so there's no waste to haul off or deal with.  Sounds like it would be a great idea for contaminated sites. 

"Garner, Robert" <rgarner(--nospam--at)moffattnichol.com> wrote:
This is not totally relevant but we recently used a hydrovac truck to assist us in removing saturated, runny soils in an exploratory pit alongside the bay.  A backhoe loosened the soils and the hydrovac sucked them out and stored them in the rear tank of the truck.  This was an ordinary vacuum truck like you would use to clean out manholes, etc.  We had a rental Baker water tank on site so the hydrovac could empty its contents into the tank for segragating the water from the soils and later disposal of the soils (contaminated also).  The remaining soils in our pit remained saturated with significant pore water pressure so our little pit would not be good for supporting much.  Those hydrovacs can sure remove a lot of material in a short time, though.  And keep your feet away from that hose - it'll take your boot right off and turn your ankle a quick 90 degrees with a loud "snap"!
 
Bob Garner, S.E.
 

From: Padmanabhan Rajendran [mailto:rakamaka(--nospam--at)yahoo.com]
Sent: Tuesday, May 23, 2006 1:13 PM
To: seaint(--nospam--at)seaint.org
Subject: "Hydrovac" for pier construction
 
In the refineries, it is becoming common to use the "hydrovac" technique for creating hole for a concrete pier construction. In essence it is water jetting method with high pressure water jet.  As the hole excavation progresses, a vacuum hose removes the loosened debris. The method is preferred because it is fast, requires minimum labor, does not create a mess and the excavated material,  which is usually defined hazardous, is removed in a compact way for suitable disposal.

Commonly used formulas for determining the vertical and lateral load bearing capacities for the concrete pier assume undisturbed soil. Are there any modified formulas for use with methods similar to "hydrovac"?

Any additional input from list members?

Thanks.

Rajendran 

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