PSN-L Email List Message
Subject: Re: concrete piers
From: John Hernlund hernlund@............
Date: Tue, 5 Nov 2002 10:51:08 -0800
At Arizona State we had a concrete pier in the basement of the Physical
Sciences building that apparently reached ten feet depth beneath the
foundation...quite expensive I imagine. The pier was about 6 foot
square and was raised two feet above the floor and had a 4 inch gap
around the edge that was filled with a very rubbery type of substance.
The filling was important for keeping water from inundating the
building, since this was a basement. The building was on top of
alluvial fan and river bed deposits, so very coarse grained material.
This did a pretty good job for long period recordings, but was not
ideal since it did not touch bed rock. A few faculty petitioned the
maintainers of Sun Devil stadium some years ago to see if they could
put one there since it was on a bedrock outcrop ("A" mountain), however
the stadium was being prepared to host Super Bowl XXX at the time, and
they didn't like the idea of putting holes in their foundation.
I would recommend that you check out the type of clay to make sure it
doesn't swell a great deal when saturated with water...
On Tuesday, November 5, 2002, at 04:19 AM, ian@........... wrote:
> having read the article on installing seismometers,
> guidelines.html ,
> I'm a little unclear on one aspect and would appreciate some advice.
> The article states that a 4 inch gap should be left around the base of
> pier. What about the rest of the pier?
> Also, the 4 inch gap seems to be filled with insulation. Won't this
> cause the
> pier to move with the insulation/surrounding ground?
> I'll be building on clay soil. How deep should I go (within reason!)
> and are
> there any other tips for clay?
> Ian Smith
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