Environmental Engineering Reference
In-Depth Information
TABLE 3.25
Typical Ranges for Elastic Constants of Various Materials
a
Material
Young's Modulus Es,
b
(tsf)
Poisson's Ratio
ν
c
Soils
Clay
Soft sensitive
25-150
Firm to stiff
150-500
0.4-0.5
Very stiff
500-1000
(undrained)
Loess
150-600
0.1-0.3
Silt
20-200
0.3-0.35
Fine sand:
Loose
80-120
Medium dense
120-200
0.25
Dense
200-300
Sand
Loose
100-300
0.2-0.35
Medium dense
300-500
Dense
500-800
0.3-0.4
Gravel
Loose
300-800
Medium dense
800-1000
Dense
1000-2000
Rocks
Sound, intact igneous and metamorphics
6-10
10
5
0.25-0.33
Sound, intact sandstone and limestone
4-8
10
5
0.25-0.33
Sound, intact shale
1-4
10
5
0.25-0.30
Coal
1-2
10
5
Other Materials
Wood
1.2-1.5
10
5
Concrete
2-3 3
10
5
0.15-0.25
Ice
7
10
5
0.36
Steel
21
10
5
0.28-0.29
a
Lambe and Whitman (1969).
b
E
s
(soil) usually taken as secant modulus between a deviator stress of 0 and ½ to 1/3 peak deviator stress in
the triaxial test
(
Figure 3.70)
(Lambe and Whitman, 1969).
E
r
(rock) usually taken as the initial tangent modu-
lus (Farmer, 1968)
(
Section 3.5.2
).
E
s
(clays) is the slope of the consolidation curve when plotted on a linear
∆
h
/
h
vs.
p
plot (CGS, 1978).
c
Poisson's ratio for soils is evaluated from the ratio of lateral strain to axial strain during a triaxial compres-
sion test with axial loading. Its value varies with the strain level and becomes constant only at large strains in
the failure range (Lambe and Whitman, 1969). It is generally more constant under cyclic loading; cohesion less
soils range from 0.25 to 0.35 and cohesive soils from 0.4 to 0.5.
Note
:
kPa
100 tsf.
Source
:
From Lambe, T.W. and Whitman, R.V., Soil Mechanics, Wiley, New York, 1969. Reprinted with permis-
sion of Wiley.
0.35 and in incohesive soils from 0.4 to 0.5. Values above 0.5 can indicate dilatant material,
i.e., the lateral strain under applied vertical stress can exceed one half the vertical strain.
Induced Stresses
Evaluation of deformation under imposed loads requires the determination of the magnitude
of stress increase (or decrease) at some depth below a loaded (or unloaded) area with respect
to the existing
in situ
stress conditions. The determination of these stresses is based on elastic
theory.
