(2) To determine which factors have the greatest

water levels of 4.0, 6.0, 7.0, 8.0, and 9.0 ft. A

influence in the performance of the sheet-pile wall

second mesh was used in this study for the purpose of

through a parametric study with the finite element

performing a parametric analysis. This mesh,

method. Variations in soil properties, loadings, sheet-

presented in Figure 10 and based on the E-105 test

pile type, and depth of penetration were considered in

section, was used to investigate design implications of

this study.

soft foundation behavior.

(3) To develop recommendations for a sheet pile

design procedure that overcomes some of the incon-

construction/loading sequence employed in the finite

sistencies in the current methods.

element analyses of both the E-99 test section and in

the parametric studies was:

(1) Computation of the initial stresses based on

(Duncan and Chang 1970) implemented in

an elastic gravity turn on analysis.

SOILSTRUCT (Clough and Duncan 1969, and

Ebeling 1990) was selected for this problem. Soil

(2) Insertion of the sheet pile.

material properties were determined from laboratory

tests and back analysis of the observational data

(3) Application of water loads in 1-ft

retrieved from the E-99 test section. The sheet piles

increments.

were treated as linear elastic materials.

(4) Application of wave loads.

finite element code, SOILSTRUCT, was modified

The stresses determined in (1) were used to determine

during the course of the study to ease the input of

material parameters for soils and to improve the

insertion of the sheet-pile wall was accomplished by

means of computing the bending moments in the sheet-

changing the material of the elements representing the

pile wall. These modifications included:

sheet-pile wall from soil to steel during the first step.

Water loads were simulated through the application of

(1) Implementation of a (*S*u/p) model to ease the

the appropriate pressure to surface nodes in contact

input of shear strength parameters.

with the floodwaters.

(2) Determination of the initial tangent modulus

of soils, *E*i, as a function of the undrained shear

obtained from the E-99 test section was used to

strength of the soil using the relationship

establish and validate the FEM for the analysis of the

sheet-pile walls. A PZ-27 sheet pile was simulated in

the analysis. Water loads were applied to simulate

water levels of elevations 4.0, 6.0, 7.0, 8.0, and

9.0 ft. Soil material properties for analysis were ob-

tained from "Q-tests" and field classifications. Three

where *K *is a unitless parameter between 250 and

shear strength profiles obtained form test data, used in

1,000 as determined from previous experience.

design, and used in the finite element analysis are

shown in Figure 11. The soil stiffness in all finite

(3) Improving the bending elements representing

element runs of the E-99 test section were made on the

the sheet piles so that the bending moments could be

assumption that K was the same for all soils. Two

directly computed.

runs were made with K = 500 and K = 1,000.

Leavell et al. (1989) concluded from the

SOILSTRUCT analysis that:

E-99 test section is shown in Figure 9. The mesh

consists of 281 solid elements and 322 nodes and

(1) Wall-versus-head relationship. The

models the foundation between elevations (el) +6.5 to

displacement at the top of the wall-versus-head

-35 ft. Sheet-pile elements are attached to soil

relationship is predicted fairly well as shown in

elements by 19 interface elements. Water loads are

Figure 12. The ability of the analysis to predict the

applied to the soil surface and pile as linearly varying

larger displacements as the head approached 8.0 ft is

distributed loads in increments corresponding to

particularly important because it implies that the limit

A-11

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