From: Roger Turk <73527.1356(--nospam--at)compuserve.com>
Date: Thu, 26 Apr 2001 13:25:34 -0400
Eric Green wrote:
. > Depends on the specifics of the soil. In general, in our local highly
. > expansive soils (Texas gulf coast), a two story building does not have
. > enough weight to stop expansion. OTOH, if you building is very heavy, it
. > might.
This reinforces a point that I have been trying to make for some time now.
The geotechs do not give us the confinement pressure, i.e., the pressure that
is necessary to prevent the soil from expanding. Once geotechs start giving
us confinement pressure, I think that we will find that non-plastic soil,
e.g., clayey sand, that has expansive clay particles will also expand and
will exert about the same pressure as a highly plastic soil containing the
same expansive clay.
The nebulous expansion index and "potential for expansion" quantification
does not give us, as structural engineers, any information on which we can
base our structural design.
It is my understanding that confinement pressure can easily run several tons
per square foot. While the weight of a building may exert similar pressures
on the footings, not too many floor slabs are designed to resist these force
A. Roger Turk, P.E.(Structural)
* This email was sent to you via Structural Engineers
* Association of Southern California (SEAOSC) server. To
* subscribe (no fee) or UnSubscribe, please go to:
* Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
* send to the list is public domain and may be re-posted
* without your permission. Make sure you visit our web
* site at: http://www.seaint.org