Design of Coastal Revetments, Seawalls, and Bulkheads

Design of Coastal Revetments,
Seawalls, and Bulkheads

Chapter 1

Introduction

1-1. Purpose
This manual provides guidance for the design of coastal
revetments, seawalls, and bulkheads.

1-2. Applicability
This manual applies to HQUSACE elements, major
subordinate commands, districts, laboratories, and field
operating activities having civil works responsibilities.

1-3. References
Required and related publications are listed in Appendix A. Bibliographic items are cited in the text by author
and year of publication, with full references listed in
Appendix A. If any reference item contains information
conflicting with this manual, provisions of this manual
govern.

1-4. Background
Structures are often needed along either bluff or beach
shorelines to provide protection from wave action or to
retain in situ soil or fill. Vertical structures are classified
as either seawalls or bulkheads, according to their function, while protective materials laid on slopes are called
revetments.
a. Revetments. Revetments are generally constructed
of durable stone or other materials that will provide sufficient armoring for protected slopes. They consist of an
armor layer, filter layer(s), and toe protection. The armor
layer may be a random mass of stone or concrete rubble
or a well-ordered array of structural elements that interlock to form a geometric pattern. The filter assures drainage and retention of the underlying soil. Toe protection is
needed to provide stability against undermining at the
bottom of the structure.
b. Bulkheads and seawalls. The terms bulkhead
and seawall are often used interchangeably. However, a
bulkhead is primarily intended to retain or prevent sliding
of the land, while protecting the upland area against wave
action is of secondary importance. Seawalls, on the other
hand, are more massive structures whose primary purpose
is interception of waves. Bulkheads may be either cantilevered or anchored (like sheetpiling) or gravity structures (such as rock-filled timber cribs). Their use is
limited to those areas where wave action can be resisted
by such materials. In areas of intense wave action, massive concrete seawalls are generally required. These may
have either vertical, concave, or stepped seaward faces.
c. Disadvantages. Revetments, bulkheads, and
seawalls mainly protect only the upland area behind them.
All share the disadvantage of being potential wave reflectors that can erode a beach fronting the structure. This
problem is most prevalent for vertical structures that are
nearly perfect wave reflectors and is progressively less
prevalent for curved, stepped, and rough inclined structures that absorb or dissipate increasing amounts of wave
energy.

1-5. Discussion
The designer is responsible for developing a suitable solution which is economical and achieves the project’s
purpose (see EM 1110-2-3300). Caution should be exercised, however, when using this manual for anything
beyond preliminary design in which the primary goal is
cost estimating and screening of alternatives. Final design
of large projects usually requires verification by hydraulic
model studies. The construction costs of large projects
offer considerable opportunities for refinements and possible cost savings as a result of model studies. Model
studies should be conducted for all but small projects
where limited budgets control and the consequences of
failure are not serious.


Source: http://140.194.76.129/publications/eng-manuals/em1110-2-1614/basdoc.pdf

Read more and go to website

Follow @all2gotweets