Environmental Engineering Reference
In-Depth Information
TABLE 3.28
Laboratory Tests to Determine Deformation Moduli of Intact Rock
Test Method
Parameters Measured
Apparatus
Performance
Comments
Static Moduli
Triaxial compression
E
i
,
E
se
,
E
t
See
Figure 3.49
and
Specimen subjected to
Modulus values controlled by
apparatus
Section 3.4.4. Rock
confining pressure and
orientation of applied load in
testing equipment
loaded axially to failure to
rocks with bedding planes,
similar but larger. USBR
obtain a stress-strain curve.
foliations, schistosity, as well as
machine can test cores of
Test repeated at various
major joints
D
15 cm and
L
30 cm
confining pressures to
under 800 tons axial
bracket
in situ
lateral
load and 6000 kg/cm
2
pressure. Strain rate can be
lateral pressure
varied to suit field loading
conditions
Unconfined compression
E
i
,
E
se
,
E
t
See
Section 3.4.4.
Can use
Specimen loaded to failure
Yields very conservative values
concrete testing
as stress-strain curve is
for most practical uses. Often
apparatus
recorded
directly applicable for mine
pillars
Dynamic Moduli
Resonant column device
E
d
,
G
d
Core specimen held
Specimen subjected first to
From specimen length and end
(sonic column)
fixed at the ends and
vibrations in the torsional
displacement as a function of
subjected to vibrations
mode, then in the
frequency.
V
s
is computed from
while axial load applied
longitudinal mode. End
the torsional test, and
V
p
(“rod”
equivalent to
displacement is monitored
compression-wave velocity)
overburden (see also
for various frequencies
from the longitudinal test
ASTM D2845)
