Dear Max,
I agree that the BS5930 soil classification system is only one way of
classifying soil materals and that much of the literature on typical values
is based on geological descriptions.
The way we handled this in our knowledge-based system was to provide a basic
hierarchy of soil groups but we allowed alternative groups to be attached at
any level. The basic heirarchy was as indicated below (not complete - just
to indicate the levels). However a user could identify a new group eg
"London Clay" and attach that to the "Clay" object in the hierarchy - or
alternatively it could be attached to "Silty Clay" if the entire group
fitted into that category.
Soil
/ | \
/ | \
Inorganic Organic Artificial
/ | \
/ | \
V. Coarse Coarse Fine
/ \ / \
Gravel Sand Silt Clay
/| |\
/ | | \
/ / \ \
/ / \ \
/ / \ \
Pure Silty Sandy Gravelly
Clay Clay Clay Clay
An alternative scheme would be to store a full soil description in the
database instead of a classification.(See: Toll, D.G. and Oliver A.J. (1995)
Structuring Soil and Rock Descriptions for Storage in Geotechnical
Databases, in Geological Data Management (ed. J.R.A. Giles), Geol. Soc.
Special Publ. No. 97, Bath: Geological Society Publishing House, pp 65-71.)
Regards
David
*******************************************
Dr David Toll
Nanyang Technological University
School of Civil & Structural Engineering
Blk N1, #1A-37, Nanyang Avenue
Singapore 639798
Tel: +65-790 6429/791 1744
Fax: +65-791 0676
e-mail: [log in to unmask]
WWW: http://www.ntu.edu.sg/home/cdtoll/
-----Original Message-----
From: Dr M.E. Barton [mailto:[log in to unmask]]
Sent: 06 January, 1999 12:02 AM
To: [log in to unmask]
Subject: RE: Request for Soil FE Data
Dear Karl,
In response to your request may I suggest that you compile FE data
for soils classified on a geological basis rather than using a soil
classification system (such as that of BS 5930). The latter give an
over-emphasis to the properties of the disaggregated materials to the
detriment of the properties and fabric of the in-situ soil. The
disaggregated grain sizes and plasticity characteristics can be common to a
wide variety of essentially very disparate materials and are inadequate as a
classification system until one brings in the geological history.
A geological classification (bringing in all the geological
factors, including statigraphy, facies type, state of weathering and
discontinuities) provides an immediate appreciation of the likely
geotechnical properties. It is also more natural in that this is the way
that much of the geotechnical literature is organised (e.g. studies of
London clay, Leda Clay, Mercia Mudstone & etc).
Best regards and a happy new year,
Max Barton.
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