Geoscience Reference
In-Depth Information
Table 1.3. Recommended values of
q
c1
N
-
Sr
Finescontent, FC (%passingNo. 200 sieve)
q
c1
N
-
Sr
10
10
25
25
50
45
75
55
fromTable1.1withtheappropriateq
cN
/(
)
60
ratiosdevelopedfromFigure1.11.Insome
cases,Seed(1987)orSeedandHarder(1990)reported
N
(
N
1
)
60cs
-
Sr
valuesandnot
(
N
1
)
60
values. In those cases,
(
N
1
)
60
values were estimated by subtracting the fines content
adjustment
N
1
)
60cs
-
Sr
. This process was applied
separatelytothedatafromeachoftheinvestigatorslistedinTable1.1,withtheresulting
(
(
N
1
)
60
from their reported values of
(
N
1
)
60
and q
c1N
values summarized in Table 1.4. The exceptions were for Cases 2 and 5
by Olson and Stark (2002), for which the table lists their reported measured q
c1N
values
of 47 and 30, respectively. For comparison, applying the above procedure to the
N
1
)
60
valuesbyOlsonandStarkproducesestimatedq
c1N
valuesof55.2and29.5forthesetwo
cases, respectively.
(
Fines content adjustments based on Table 1.3 were then added to the values of q
c1N
to arrive at the corresponding values of q
c1Ncs
-
Sr
. These q
c1Ncs
-
Sr
values are listed in
Table 1.5 along with the S
r
/
σ
vo
values computed for each case history and each inves-
tigator. These data are plotted in Figure 1.12 together with the S
r
/
σ
vo
-q
c1Ncs
-
Sr
curves
representedbyequations(1.9)and(1.10).ComparisonoftheCPT-basedresultspresented
in this figure with those shown in Figure 1.5 for the SPT-based results indicate a reason-
ably good consistency and correlation between the two approaches.
5. Concluding remarks
SPT-andCPT-basedrelationshipsforestimatingtheresidualshearstrengthratio,S
r
/
σ
vo
,
ofliquefiednonplasticsoilsinthefieldarerecommendedinthispaperbasedonareview
of prior case history studies, laboratory studies, and recent findings regarding void redis-
tribution mechanisms. The recommended relationships are comparable with values rec-
ommendedbyotherinvestigatorsforvaluesofequivalentcleansandSPTcorrectedblow
counts,
N
1
)
60cs
-
Sr
,lessthanabout13orequivalentcleansandCPTnormalizedcorrected
penetration resistances, q
c1Ncs
-
Sr
, less than about 75, which is where the majority of the
available case history data are. The recommended relationships provide new guidance,
however, regarding the unavoidable task of having to extrapolate beyond the available
casehistorydataintheprocessofestimatingresidualstrengthsofsoilshaving
(
(
N
1
)
60cs
-
Sr
values greater than about 14or q
c1Ncs
-
Sr
values greater than about 80.
The development of the recommended design relationships, and particularly their extra-
polationtopenetrationsresistancesthataregreaterthanrepresentedbyavailablecasehis-
tory data, has been guided by the results of undrained laboratory test studies and recent
