FLOOD03439

• County: Statewide
• Basin: Statewide
• Title: Design of Sheet Pile Walls
• Date: 3/31/1994
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Educational/Technical/Reference Information

EM 1110.2.2504
31 Mar 94

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NIT K:TNE PRESSURE

Figur. 5-5. Typical n. pr.ssur. distributions

snd classified as !he "Free Earth" method (implied in
Figure S-2b) and variations of the "FIXed Earth" hypoth.
esis. Research and experience over the years have
shown !hat walls designed by the Free Earth method are
suflicenlly stable walls with less penetration Ihan those
designed by !he Fixed Earth method. Because of !he
fIexibilily of !he sheel piling. !he Free Earth method
predicts larger moments Ihan those !hat actually occur.
This shoncoming of the Free Earth method is overcome
by using Rowe's momenl reduction curves. as described
in Chapter 6. In the Free Earth method. the anchor is
assumed to be a rigid simple support aboul which the
wall rotates as a rigid body as shown in Figure 5-2b.
Despite the tendency of the wall to pOOuce a passive
condition in !he relained soil above !he anchor. it is
assumed !hat the wall is only subjected to the net active
pressure distribution as illustraled in Figure 5-7. The
required depth of penettation (d in Figure 5-7) is dew-
mined from !he equilibriwn requirement !hat the sum of
moments aboul the anchor must be zero. After the
deplh of penelration has been determined. the anchor
force is obtained from equilibriwn of horizontal forces.
Because the position of the anchor affects boIII depth of

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\\~ NIT P~SNE PRESSURE

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penelration and anchor force. il will be neceSS8JY to
consider several anchor positions to anive a1the optimal
combination. For an initial estimate. the anchor may be
assumed to lie aI a distance below the top of the wall
equal 10 one-fourth 10 one-third of the exposed wall
heighL

h. Anchor design. The anchor force calculated in
the stabilily analysis was obtained from equilibrium of a
lypicall-fOOI slice of !he wall. In the actual system the
anchor support is provided by discrete tie rods attached
to the wall Ihrough wales and to another support
mechanism (Iermed the "anchor" herein) aI their ends
and remote from the wall, Structural design of the tie
rods and wales is discussed in Chapter 6, A variel)' of
anchor configurations are illustrated in Figure 2-2.
Capacities of some anchor configurations are discussed
in the following paragraphs. The soil strength
paramelerS appearing in the equations associaled with
anchor design should be consistent with !he properties
(S-<:ase or Q-case) used for stabilily design. In all cases
the capa.::ily of !he anchor should be sufficienl 10
develop the yield strength of the tie rods (Chapter 6).

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