Environmental Engineering Reference
In-Depth Information
(a)
(b)
Gamma probe
Insulation
Triaxial geophones
or accelerometer
(
V
p
&
V
s
)
Electrodes
Photo
multiplier
tube
Gamma ray
excitation
Csl crystal
Triaxial geophones
or accelerometer
(
V
p
&
V
s
)
Inclinometer (
I
)
Thermistor (
T
)
Friction sleeve
(
F
s
)
Inclinometer
(
l
x
&
l
y
)
Thermistor (
T
)
Load cells
Friction sleeve (
F
s
)
Load cells
Pore pressure
transducer (
U
)
Pore pressure
transducer (
U
)
Active source
Porous filter
element
Porous filter
element
Cone tip (
Q
c
)
Cone tip (
Q
c
)
FIGURE 2.39
Various types of cone penetrometers. (a) Piezo cone penetrometer (CPTU): measures tip resistance, shaft
friction, pore pressures, temperature, inclination, and shear wave velocities. (b) Active gamma penetrometer:
GCPT measures
in situ
soil density, particularly useful in sands which are difficult to sample undisturbed.
(c) Electrical resistivity cone (RCPT): provides measures of relative soil resistivity. (Courtesy of ConeTec.)
Cone: 10TONAD 010
Date: 12:08:9411:53
Site: 2001 CPTBT
Location: Test site
Qt bar
Fs bar
Rf%
U metres
SBT
0
250
0.0
2.5
0.0
5.0
0
120
0
12
−
0.0
Drilled Out
Drilled Out
Drilled Out
Sensitive fines
Clay
Clayey silt
Sample 1
−
5.0
Silt
Clayey silt
Clayey silt
Silt
Sample 2
Silt
−
10.0
Silty sand/sand
Sample 3
Sand
Silty sand/sand
Silty sand/sand
Sand
−
15.0
Silty sand/sand
Sand
Silty sand/sand
Silty sand/sand
Sample 4
Silty sand/sand
−
20.0
Silty sand/sand
Sand
Sample 5
−
25.0
Sand
Sand
Sample 6
Sand
−
30.0
Max. depth: 45.75 m
Depth Inc: 0.05 m
SBT: Soil behavior type (Robertson et al., 1990)
Estimated phreatic surface
FIGURE 2.40
Sample of CPTU log. Data plots are provided in real time. (Courtesy of ConeTec.)
A
vision cone penetrometer
(VisCPT) has been developed recently to overcome the prob-
lem of no recovered samples (Hryciw et al., 2002). Miniature cameras are installed in the
CPT probe, and continuous images of the soil's stratigraphy are obtained through syn-
thetic sapphire windows mounted in the side of the probe.
