Civil Engineering Reference
In-Depth Information
10.6.3 Ultimate compressive resistance from ground tests results
The design compressive resistance can be determined from ground tests results. Here the characteristic
compressive resistance, R
c;k
, is taken as the lesser value of:
(
R
+
R
)
(
R
+
R
)
b cal
;
s cal mean
;
b cal
;
s cal
;
min
R
c k
and R
=
=
;
c k
;
ξ
ξ
3
4
Where
(R
b;cal
)
mean
=
the mean calculated base resistance
(R
s;cal
)
mean
=
the mean calculated shaft resistance
(R
b;cal
)
min
=
the minimum calculated base resistance
(R
s;cal
)
min
=
the minimum calculated shaft resistance
ξ
3
,
ξ
4
Annex).
The calculated base and shaft resistances are determined using the equations set out in Section
10.5.
Table 10.4A
Correlation factors - ground tests results (from EN1997-1:2004,
Table A10).
Number of test profiles
1
2
3
4
5
7
10
1.4
1.35
1.33
1.31
1.29
1.27
1.25
ξ
3
1.4
1.27
1.23
1.20
1.15
1.12
1.08
ξ
4
Table 10.4B
Correlation factors - ground tests results (from NA to BS EN1997-
1:2004, Table A.NA.10).
Number of test profiles
1
2
3
4
5
7
10
ξ
3
1.55
1.47
1.42
1.38
1.36
1.33
1.30
ξ
4
1.55
1.39
1.33
1.29
1.26
1.20
1.15
Example 10.6:
Ground tests results
A 10 m long by 0.7 m diameter CFA pile is to be founded in a uniform soft clay. The
following test results were established in a geotechnical laboratory as part of a site
investigation:
Borehole no.
1
2
3
4
Mean undrained strength along
shaft, c
u;shaft
(kPa)
65
62
70
73
Mean undrained strength at base,
c
u;base
(kPa)
90
79
96
100
