TM 5-820-4/AFM 88-5, Chap. 4
Table C-3. Suggested Maximum Cover Requirements for Corrugated-A luminum-A lloy Pipe,
Riveted, Helical, or Welded
Fabrication 2 2/3 Inch Spacing, -Inch Deep Corrugations
H-20 Highway Loading
Suggested Maximum Cover Above Top of Pipe, ft
Vertically Elongated Section
U.S. Army Corps of Engineers
1. Corrugated-aluminum-alloy pipe will conform to the requirements of Federal Specification W W-P-402.
2. The suggested values shown are for average conditions and are to be considered as guidelines only for dead load plus
H-20 live load Cooper E-80 railway loadings should be independently made.
3. Soil conditions, trench width and bedding conditions vary widely throughout varying climatic and geographical areas.
4. Calculations to determine maximum cover should be made for all individual pipe and culvert installations underlying
roads, streets and open storage areas subject to H-20 live loads.
5. Cover depths are measured from the bottom of the subbase of pavements, or the top of unsurfaced areas, to top of pipe.
6. Calculations to determine maximum cover for Cooper E-80 railway loadings are measured from the bottom of the tie
to the top of the pipe.
7. Vertical elongation will be accomplished by shop fabrication and will generally be 5 % of the pipe diameter.
8. See table C-9 for suggested minium cover requirements.
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separate cover analysis must be performed.
C-7. Strength of pipe.
shall be considered
of ample strength when it meets the conditions
Tables C-1 and C-2 indicate
C-8 Rigid pipe.
specified for the loads indicated in tables C-1
maximum and minimum cover for trench conduits
through C-8. When railway or vehicular wheel loads
employing asbestos-cement pipe and concrete pipe.
or loads due to heavy construction equipment (live
If positive projecting conduits are employed they are
loads, LL) impose heavier loads, or when the earth
those which are installed in shallow bedding with a
(or dead loads, DL) vary materially from those nor-
part of the conduit projecting above the surface of
mally encountered, these tables cannot be used for
the natural ground and then covered with an em-
pipe installation design and separate analyses must
bankment. Due allowance will be made in amounts
be made. The suggested minimum and maximum
of minimum and maximum cover for positive pro-
cover shown in the tables pertain to pipe installa-
jecting conduits. Table C-9 suggests guidelines for
tions in which the back fill material is compacted to
minimum cover to protect the pipe during con-
at least 90 percent of CE55 (MIL-STD-621 ) or
struction and the minimum finished height of cover.
AASHTO-T99 density (100 percent for cohesionless
C-9. Flexible pipe. Suggested maximum cover
sands and gravels). This does not modify require-
for trench and positive projecting conduits are in-
ments for any greater degree of compaction speci-
dicated in tables C-3 through C-6 for corrugated-
fied for other reasons. It is emphasized that proper
aluminum-alloy pipe, corrugated-steel pipe, struc-
bedding, backfilling, compaction, and prevention of
tural-plate-aluminum-alloy pipe, and structural-
infiltration of backfill material into pipe are impor-
plate-steel pipe. Conditions other than those stated
tant not only to the pipe, but also to protect overlying
in the tables, particularly other loading conditions
and nearby structures. When in doubt about mini-
will be compensated for as necessary.
mum and maximum cover for local conditions, a
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