Environmental Engineering Reference
In-Depth Information
TABLE 3.4
(
Continued
)
Category — Tool or Method
Applications
Limitations
Section
Pressure testing
Measures
k
h
in vertical borehole
Requires clean borehole
3.3.4
walls Pressures can cause
joints to open or to clog
from migration of fines
Shear Strength
Direct shear box
Measures strength parameters
Sawing block specimen
3.4.3
along weakness planes of
and test setup costly.
rock block
A surface test. Several
tests required for Mohr's
envelope
Triaxial or uniaxial
Measures triaxial or uniaxial
Same as for direct shear box
3.4.3
compression
compressive strength of
rock block
Borehole shear device
Measures
φ
and
c
c
in borehole
3.4.3
Dilatometer or Goodman
Measures limiting pressure
See Dilatometer under
3.5.3
jack
P
L
in borehole
Deformation. Limited by
rock-mass strength
Deformation Moduli (Static)
Dilatometer or Goodman
Measures
E
in lateral direction
Modulus values valid for
3.5.3
jack
linear portion of load-
deformation curve. Results
affected by borehole roughness
and layering
Large-scale foundation-
Measures
E
under footings or
Costly and time-consuming
3.5.4
load test
bored piles. Measures shaft
friction of bored piles
Plate-jack test
Measures
E
: primarily used for
Requires excavation and
3.5.3
tunnels and heavy structures
heavy reaction or adit.
Stressed zone limited by plate
diameter and disturbed by
test preparation
Flat-jack test
Measures
E
or residual stresses
Stressed zone limited by
3.5.3
in a slot cut into the rock
plate diameter. Test area
disturbed in preparation.
Requires orientation in
same direction as applied
construction stresses
Radial jacking tests
Measures
E
for tunnels.
Very costly and time-
3.5.3
(pressure tunnels)
Data most representative of
consuming and data
in situ
rock tests and
difficult to interpret.
usually yields the
Preparation disturbs
highest values for
E
rock mass
Triaxial compression test
Measures
E
of rock block
Costly and difficult to set up.
3.5.3
Disturbs rock mass during
preparation
Dynamic Properties
Seismic direct methods
Obtain dynamic elastic moduli
Very low strain levels yield
3.5.3
E
,
G
,
K
, and v in boreholes
values higher than static
moduli
(
Continued
)
