ETL 1110-2-544
31 Jul 95
Figure 7. Calculated and measured wall deflections
Figure 6. Earth pressures on tieback wall
h. Comparison with measurements. The wall
was instrumented with inclinometer casings and strain
gages. Figures 7 and 8 show the comparisons
between calculated and measured deflections and
bending moments. In both cases, the curve marked
"Initial" represents the calculated values from the SSI
analysis when the soil stiffness obtained from the
laboratory tests was used in the analyses. The
calculated deflections and moments exceeded the
measured values.
i. Parameter studies performed after making
field measurements. After the field measurements
were obtained, additional parameter studies were
performed in an attempt to better match observed
Figure 8. Calculated and measured bending
behavior. By tripling the soil stiffness obtained from
moments
laboratory test data, a reasonably good match could be
obtained. Figures 7 and 8 show the comparison. This
penetration required for stability. Conventional design
result is in agreement with the experience on other
practice incorporates both a limit equilibrium program
projects that laboratory data frequently underestimate
and a beam-spring program to predict the stability of
in situ soil stiffness.
the system and the deflections of the sheet pile to
determine if a given layout will meet design criteria.
The calibrated model could be used, if necessary, to
A full-scale test program and finite element analysis
calculate the response of the system to further
were performed as part of this study to investigate the
loadings, such as surcharges or additional excavation.
effectiveness of the current design procedures.
b. Purposes. This study had three primary
2-9. Case History: Sheet-pile Wall Analysis
puposes:
a. Project description. Sheet-pile walls are
(1) To demonstrate the applicability of the finite
used for both flood protection along the Mississippi
element method to sheet-pile wall design in soft clays
and Atchafalaya Rivers and hurricane protection
by analysis of the full-scale E-99 test section sheet-pile
along the Gulf of Mexico. The cost of the walls
wall.
depends on the sheet-pile section and the depth of
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