Paul,
The problem with peat is that it is very variable but can be classified into
two types amorphous or fibrous. As an example the voids ratio can vary from
8 to 25 respectively, more importantly the drainage characteristics vary
greatly even amongst the fibrous type depending on its composition. Loading
the peat can change the permability by several orders of magnitude making
predictions of settlement a crystal ball job. Added to the fact that in an
undrained bog it will have negligible undrained shear strength at near the
surface.
However, it is not all bad news particularly if you do not disturb the top
surface. Geosynthetics provide a good filter and provided you are prepared
to accept long term settlement, i.e. secondery consolidation. Flexible
structures can be constructed. A word of warning if you change the drainage
then shrinkage of the peat occurs, i.e the level of Chat Moss between
Warrington and Manchester has reduced by over 1 metre after the M62 was
constructed due to changes in the drainage patterns of the area (not all
caused by the motorway). I have seen similar effects when a pipe line has
been installed because the trench has provided a new drainage path out of
the bog.
As for general parameters, I refer to the Ground Engineer's Handbook but it
only reports general ranges of parameters.
Alex Carson
Principal Engineer
Atkins
3 Rutherford Court
Staffordshire Technology Park
Stafford ST18 0AR
Tel: 01785 218254
Fax: 01785 218251
email [log in to unmask]
www.atkinsglobal.com
-----Original Message-----
From: Geotechnical Engineering Email List
[mailto:[log in to unmask]] On Behalf Of Ng, Paul
Sent: 05 September 2005 15:42
To: [log in to unmask]
Subject: Engineering properties of peat bogs
Dear colleagues,
Could you point me to any published engineering properties of peat bogs
please. Properties for Irish peat would be particularly useful.
Thanks in advance
Paul
----------------------------------
Dr Paul C. F. Ng
Senior Geotechnical Engineer
Advantica
Ashby Road
Loughborough
Leicestershire
LE11 3GR
UK
Tel: +44 (0)1509 282032
Fax: +44 (0)1509 283119
Mobile: +44 (0)7789 480904
E-mail: [log in to unmask]
http://www.advantica.biz
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