Geoscience Reference
In-Depth Information
Table 4.10
Cone penetration tests.
Symbol
Test
q
c
Measured cone resistance (MPa)
q
T
Corrected cone tip resistance (MPa): q
T
=
q
c
+
−
a
N
)
u
b
(1
a
N
Net area ratio provided by manufacturer
0.75
a
N
0.82 for most 10 cm
2
penetrometers
<
<
0.65
a
N
0.8 for most 15 cm
2
penetrometers
<
<
F
s
Sleeve frictional resistance
FR
Friction ratio
F
s
/q
c
=
u
0
In - situ pore pressure
B
q
Pore pressure parameter - excess pore pressure ratio
B
q
(u
d
u
0
)
/(q
T
P
o
)
=
−
−
P
o
Effective overburden pressure
u
d
Measured pore pressure (kPa)
u
u
u
d
u
0
=
−
T
Time for pore pressure dissipation (sec)
t
50
Time for 50% dissipation (minutes)
•
The dissipation tests which can take a few minutes to a few hours has proven
more reliable in determining the coefficient of consolidation, than obtaining that
parameter from a consolidation test.
Figure 4.2
Cone penetration test.
4.11 Dilatometer
•
A Dilatometer test is most useful when used with a CPT.
•
It has a very high production rate, but below that of the CPT.
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