Geoscience Reference
In-Depth Information
•
Group 3
: Case histories with only estimated in-situ measurements (e.g., SPT, CPT)
but the geometric details are reasonably complete. Five case histories (Cases No.
14-18) fit this category.
Ofthe13 casehistoriesinTable 1.1 within-situmeasurements (Groups 1and2), allhad
data on SPT blow counts while only four had data on CPT penetration resistances. For
this reason, the correlation between residual strength and SPT blow counts is developed
first, using the SPT blow counts that were reported or estimated by the researchers listed
in Table 1.1.
N
1
)
60cs
-
Sr
, for each case
history are listed in Table 1.1. The equivalent clean sand SPT corrected blow count,
(
(
Values of equivalent clean sand corrected SPT blow count,
N
1
)
60cs
-
Sr
, is obtained from the corrected SPT blow count,
(
N
1
)
60
, by the addition of
(
N
1
)
60
-
Sr
, which is afunction offines content, FC. Thus,
(
N
1
)
60cs
-
Sr
=
(
N
1
)
60
+
(
N
1
)
60
-
Sr
(1.1)
The values of
N
1
)
60
-
Sr
initially proposed by Seed (1987) are listed in Table 1.2. Seed
andHarder(1990)usedthese
(
N
1
)
60
-
Sr
values,whereasOlsonandStark(2002)didnot
include any adjustments for FC in their studies. There are insufficient data to constrain
any derivation of
(
N
1
)
60
-
Sr
, but the values recommended by Seed (1987) continue to
appear reasonable. Consequently, the values of
(
N
1
)
60cs
-
Sr
listed in Table 1.1 are those
reported by the respective investigators, with the addition of
(
(
N
1
)
60
-
Sr
for the values
published by Olson and Stark (2002) asnecessary.
Several other investigators have contributed to the analysis of case histories, including
thosereferencedinthefootnotestoTable1.1.Wrideetal.(1999)back-calculatedvalues
of S
r
for most of the cases listed in Table 1.1, but chose to use the minimum value of
(
N
1
)
60
creates two
difficulties, namely: (1) it is not certain that the data available for a given case history
included the “minimum” value of
N
1
)
60
for correlating to S
r
. The choice of the minimum value of
(
N
1
)
60
; and (2) an inordinate amount of drilling and
samplingwouldberequiredinforwardapplicationsforasitetoensurethattheminimum
value of
(
N
1
)
60
has been obtained. For these reasons, the results by Wride et al. are not
includedinTable1.1.Itisnoted,however,thatthevaluesofS
r
back-calculatedbyWride
et al. arenot materiallydifferent fromthose listedin Table 1.1.
(
Table 1.2. Values of
(
N
1
)
60
-
Sr
recommended by Seed (1987
)
Finescontent, FC(%passing No. 200 sieve)
(
N
1
)
60
-Sr
10
1
25
2
50
4
75
5
