Geoscience Reference
In-Depth Information
Table 4.11
Dilatometer testing.
Symbol
Test
p
o
(MPa)
Lift - off pressure (corrected A - reading)
p
1
(MPa)
Expansion pressure (correctedB-reading)
I
D
Material index (I
D
)
(p
1
p
o
)
/(p
o
u
0
)
=
−
−
u
0
Hydrostatic pore water pressure
E
D
Dilatometer modulus (E
D
)
=
34.7 (p
1
−
p
o
)
K
D
Horizontal stress index (K
D
)
(p
o
u
0
)
/
σ
vo
=
−
σ
vo
Effective vertical overburden stress
4.12 Pressuremeter test
•
The Pressuremeter test should be carried out with the appropriate stress range.
•
It is useful for in situ measurement of deformation.
Table 4.12
Pressuremeter testing.
Symbol
Test
P
o
(MPa)
Lift - off pressure
P
L
(MPa)
Limit pressure
P
0
Total horizontal stress
P
0
σ
=
ho
E
PMT
Young's modulus (E
PMT
)
)
(V/
V)
P
=
2(1
+
ν
Poisson's ratio
ν
V
Current volume of probe
=
V
0
+
V
V
0
Initial probe volume
V
0
=
V
Measured change in volume
P
Change in pressure in elastic region
4.13 Vane shear
•
Some shear vanes have a direct read - out (kPa). These are usually limited to
shallow depth testing.
•
Values change depending on shape of vane.
Table 4.13
Vane shear testing.
Symbol
Test
s
uv
(kPa)
Vane strength (s
uv
6T
max
/(7
D
3
)
for H/D
2
=
π
=
D
Blade diameter
H
Blade height
T
max
Maximum recorded torque
s
uv
(peak)
Maximum strength
s
uv
(remoulded)
Remoulded strength (residual value) -
vane is rotated through 10 revolutions)
Vane shear correction factor
µ
s
uv
(corr)
s
uv
(corr)
s
uv
= µ
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