605
Technical Committee 102 /
Comité technique 102
0
5
10
15
20
5
6
7
8
9
10
11
q
t
(MPa)
Depth (m)
60 mm/s
0.5 mm/s
Figure 3 Comparison of the smoothed cone resistance conducted with a
penetration rate of 60 and 0.5 mm/s. The figure contains results from 3
CPTs test for each penetration rate.
0 20 40 60 80 100 120 140 160 180
5
6
7
8
9
10
11
f
s
(kPa)
Depth (m)
60 mm/s
0.5 mm/s
Figure 4. Comparison of the smoothed sleeve friction conducted with a
penetration rate of 60 and 0.5 mm/s. The figure contains results from 3
CPTs test for each penetration rate.
4 CORRELATION BETWEEN PENETRATION RATE
AND MEASURED PARAMETERS
The order of the change in the cone penetrations parameters that
can be anticipated is however difficult to read from Figure 2,
Figure 3 and Figure 4. As a result, the mean value of the entire
silt layer from all CPTs (CPTs with penetration rate of 60, 20, 5,
1 and 0.5 mm/s) can be plotted in a semi logarithmic plot. This
has been done for the sleeve friction in Figure 5.
Just as Figure 4, Figure 5 does not show any correlation
between the mean sleeve friction and the mean penetration rate.
According to Lunne et al. (1997) the sleeve friction does not
give consistent results during cone penetration. The results
shown in Figure 4 and Figure 5 substantiate this, for which
reason caution must be taken when using the sleeve friction to
analyse CPT data.
The mean value for the pore pressure and cone resistance
plotted against the mean penetration rate in a semi logarithmic
plot is seen in Figure 6 and Figure 7. It can be seen that a
correlation between the pore pressure and the penetration rate
(Figure 6) and cone resistance and the penetration rate (Figure
7) exist.
0.1
1
10
100
70
80
90
100
110
120
130
140
Penetration rate (mm/s)
f
s
(kPa)
Mean values
Figure 5. The mean sleeve friction plotted against the mean penetration
rate from 4.5 to 11.4 m below ground level. No correlation seems to
exist. The standard rate of penetration of 20 mm/s has been marked with
a dotted line.
0.1
1
10
100
0
50
100
150
200
250
300
350
Penetration rate (mm/s)
u
2
(kPa)
Fitting curve
Mean values
Figure 6. Correlation between the mean pore pressure and the mean
penetration rate from 4.5 to 11.4 m below ground level. The standard
rate of penetration of 20 mm/s has been marked with a dotted line.
0.1
1
10
100
0
2
4
6
8
10
12
Penetration rate (mm/s)
q
t
(MPa)
Fitting curve
Mean values
Figure 7. Correlation between the mean cone resistance and the mean
penetration rate from 4.5 to 11.4 m below ground level. The standard
rate of penetration of 20 mm/s has been marked with a dotted line.
