Mallickarjun,
Phhysical property data are best obtained from testing the actual unit in
question, usually not a very expensive undertaking, geotechnical engineers do
this sort of testing, at least for Young's Modulus all the time. For
back-of-the-envelope-calculation purposes, both rocktypes, when unweathered,
are both very strong and very stiff as rock goes.
A data set for gneisses and gabbroic gneisses in southern New England, USA I
have has an average Young's modulus of 54 GPa, a standard deviation of 17 GPa
and a sample size of 106 samples.
By percentiles, the distribution looks like this
min = 21.2 GPa
10% = 31.3 GPa
50% = 54.4 GPa
90% = 76.9 GPa
max = 90.7 GPa
This might give you a very rough range to work with, though it should also
indicate the variability from sample to sample, and perhaps the need to test
your own rocks.
These are for room temperature only, the physical properties will vary
considerably as the rock is heated to geological conditions.
The effect of fabric on the physical properties matters, not so much with
gabbros, but the more foliated and schistose your gneisses are, the more
anisotropic the rock will be. Generally, schists are stiffer (higher Young's
modulus) when tested perpendicular to the foliation than when tested parallel
to the foliation. In planning any testing programme, it is best to test both
perpendicular to foliation, and parallel to foliation.
As to coefficent of expansion, I don't know much.
Hope this helps.
best,
Sam
--
Samuel H. Haines
PhD candidate
Dept. of Geological Sciences
University of Michigan
Rm 2534, C.C. Little Building
425 E. University Ave
Ann Arbor, MI, 48109-1063
USA
+1 (734) 647-2157 (W)
+1 (734) 646-0512 (H)
...quod scripsi, scripsi
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