TM 5-809-6/AFM 88-3, Chap. 6
CHAPTER 4
SITE STRUCTURES
4-1. Drainage structures
publications by the manufacturers of proprietary products
and systems will be consulted as necessary.
a. Box culverts. Concrete box culverts will be designed
b. Retaining structures. Retaining structures can be
for loadings defined in the AASHTO Standard Specifications
classified with respect to the manner in which forces are
for Highway Bridges in accordance with design requirements
transmitted to the surrounding soil as either gravity, can-
presented therein. Consideration will also be given to
tilever, or anchored types. Though numerous variations exist
requirements set forth in ASTM C 789 and C 850 as
within each general type, only a few are identified in the
applicable. Box culverts, if constructed of other materials,
following discussions.
will be designed in accordance with the generally recognized
(1) Gravity structures. Gravity structures are those
codes and standards applicable to such materials.
which rely solely on their own weight to maintain stability.
b. Manholes and inlets. Manholes and inlets will be
Among the types of construction which act as gravity
designed to resist earth, water, temperature, and other loads
structures are concrete gravity blocks, bin or cellular cof-
to which they will be subjected. Structural design of concrete
ferdams, crib walls, bin walls, gabions, and reinforced earth
structures will be in accordance with ACI 318. Design of
type structures.
other types of manhole construction will be in accordance
(2) Cantilever structures. Cantilever structures are
with applicable codes covering that type of construction.
those which interact with the surrounding earth through
Additional guidance for watertight construction and load
flexural bending in such a way that a portion of the earth
distribution coefficients for these types of structures may be
mass is brought into play in resisting the forces imposed on
found in PCA IS003.02D and IS072.0lD. Special
the structure. Among the types of construction which act as
consideration will be given to the effect of roof and wall
cantilever structures are reinforced concrete "tee" walls,
openings, and proper allowance will be made for differential
counterfort or buttress walls, cantilevered concrete or steel
movement due to settlement, thermal expansion, etc.,
sheet piles, overlapping drilled piers, and reinforced concrete
between manholes and interconnecting elements. To the
slurry walls.
extent practical, precast components for manhole
(3) Anchored bulkheads. Anchored bulkhead type
construction will be used. Precast components will be
structures are structures which typically employ a flexural
furnished in accordance with ASTM C 478.
"wall" type element to retain the earth and an anchor system
c. Miscellaneous drainage structures. Corrugated cul-
connected near the top of the wall to reduce the magnitude of
vert pipes will be designed in accordance with American Iron
the reactions at the base of the wall. Typical anchored
and Steel Institute (AISI) SG-861. Concrete culvert pipe will
bulkhead type structures are anchored bulkhead waterfront
be reinforced and furnished in accordance with ASTM C 76.
structures, soldier beam and lagging systems, braced walls,
Required three edge bearing strength will be determined in
and slurry walls when anchored near their top. Depending on
consideration of class of bedding and applicable load factor
the characteristics of the earth materials, the stiffness of the
as set forth in Foundation Engineering by Leonards.
wall, etc., the base of the wall of such structures may be
Corrugated aluminum culvert pipe will be furnished in
considered to be rotationally fixed to some degree which
accordance with ASTM B 745. Other materials will be
results in a reduction in the required flexural strength for the
considered subject to acceptance by the appropriate
wall. There are also a number of options available regarding
headquarters provided any special requirements such as
the type of anchor structure which can be used including
bedding, etc., are met.
anchor wall, batter pile system, earth or rock anchors, etc.
d. Sewers. Criteria for structural design of the various
c. Shore protection structures. Shore protection struc-
components of sewer systems will be established from
tures will be designed as described in the CERC Shore
information presented in Water Pollution Control Federation
Protection Manual, Volumes I through III. Additional
(WPCF) MOP9CTG, TM 5-814-1/AFM 88-11, Volume 1,
information available from manufacturers of specialized
and TM 5-814-2/AFM 88-11, Volume 2.
shore protection products, e.g., revetment mattresses, in-
terlocking articulated blocks, etc., will be considered where
4-2. Earth related structures
the use of such systems is warranted. Care will be taken in
a. General. NAVFAC DM-7.1, DM-7.2, and DM-73
selection of material for such systems and regard given to the
will be the basic references for design of earth related
possibility of reduced service life when artificial materials
structures. Additional references including MIL-HDBK-
are used.
1025/4, the Structural Engineering Handbook by Gaylord &
Gaylord, Foundation Analysis and Design by Bowles,
Principles of Foundation Engineering by Das, as well as
4-1
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