Geoscience Reference
In-Depth Information
Fig. 1.3. Back-calculation ofthe residual shear strength for the liquefied shell materials
of Lower San Fernando Dam usinglimitequilibrium analyses (from Seed, 1987)
significant and uncertain step in the interpretation of the case histories, which adds con-
siderably tothealreadylarge uncertainty inestimatedS
r
values. Itshould alsobekept in
mind that what is needed for forward applications is the estimate of S
r
during the early
stages of instability rather than at some later stage (e.g., after significant intermixing has
occurred).
EighteencasehistoriesarelistedinTable1.1usingthevaluespublishedbySeed(1987),
Seed and Harder (1990), and Olson and Stark (2002). Seed (1987) evaluated 12 case
histories;tenofthesearelistedinTable1.1,whiletwocasehistoriesoflateralspreading
were omitted. Seed and Harder (1990) reevaluated the 12 cases originally investigated
by Seed (1987) plus an additional five cases; 13 of their cases are listed in Table 1.1,
while three cases of lateral spreading and one case of limited embankment slumping
were omitted. Olson and Stark (2002) evaluated 33 case histories, which included 15 of
the cases investigated by Seed and Harder. Olson and Stark (2002) utilized a number of
procedures to back-calculate S
r
. Among these procedures is the kinetic analysis, which
theyconsideredtoprovidethemoreaccurateestimationofS
r
.Onlytencaseshadenough
subsurface and geometric information for them to complete the kinetic analysis. They
note that the procedures they used for the other cases were likely to underestimate S
r
.
Accordingly, onlytheir resultsbased onkinetics are included in Table 1.1.
The18publishedcasehistorieslistedinTable1.1canbecategorizedintothreegroupsas
follows:
•
Group 1
: Case histories with an adequate amount of in-situ measurements (e.g.,
SPT, CPT) and reasonably complete geometric details. Seven case histories (Cases
No. 1-7) fit thiscategory.
•
Group 2
:Casehistorieswithanadequateamountofin-situmeasurements(e.g.,SPT,
CPT) but the geometric details are incomplete. Six case histories (Cases No. 8-13)
fit this category.
