FLOOD06430

• County: Statewide
• Basin: Statewide
• Title: Conduits, Culverts and Pipes
• Date: 3/3/1969
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Educational/Technical/Reference Information

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EM 1110--2-2902
3 Mar 1969
Table 1
tan' (45' - ~)
~ tan~ '2
0 0 1.00
10 0.176 0.70
20 0.364 0.49
25 0.466 0.41
30 0.577 0.33
35 0.700 0.27
40 0.839 0.22
45 1.000 0.17
50 1.192 0.13

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Where submergence and water surcharge ar~ applicable, the loadings must be modified ac-
cordingly. To obtain the total vertical load, the weight of the projected volume of water above
the conduit, including any surcharge water above the fill surface, is added to the larger value
of W. obtained by using the submerged weight of the material in equations 2 and 3. The hori-
zontal pressure is obtained by adding the full hydrostatic pressure to the pressure found by equa-
tion 4 using submerged weight of material.
(2) Condition 11 applies to conduits and culverts that are completely buried in a ditch
with a superimposed fill, H" above the top of the ditch, as shown on plate 3. To comply with
this condition, the ditch width and side slopes must satisfy the same limitations as specified for
Condition 1. The vertical load and the horizontal unit pressure for this condition will vary be-

tween computed values for Conditions I and III in proprotion to the ratio H Hr h
. + .
The vertical load, in pounds per foot of cui vert length, for Condition II should be computed
as the larger of the two values obtained from the following equations:

W. = Coy b.' + Hr (1.5 y b.Hb - Coy boO) _ _ __ __ __ __ __ __ __ __ _ _ _ __ _ __ _ __ __ (5)
H, + h.

or

W. = Y b.Hb + H, (1.5 y b.Hb - Y b.Hb) _ __ __ __ _ __ __ __ _ __ __ _ __ __ _ _ __ __ __ (6)
H. +h.
For low fills it may be desirable to use on elf ective height slightly less than Hb.
The horizontal unit pressure in pounds per square foot may be computed from the following
equation:

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P. = yHtan' (450 - +/2) + H ~h [O.5yH - yHtan' (450 - +/2)]________________(7)
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For cases with submergence and water surcharge, the horizontal and vertical earth pres-
sures for this condition should be similarly proportioned between the results obtained for Con-
ditions I and III with surcharge, and added to the hydrostatic pressure.
(3) Condition III applies to conduits and culverts that project above an embankment sub-
grade and to conduits and culverts in ditches that do not satisfy the requirements of Condition I
or II. For this condition, the design should cover a range of possible loading conditions from the
initial condition to the long time condition by satisfying two extreme cases: Case 1, with P.!w, =
0.33 (w. = 150% vertical projected weight of fill material: lateral earth pressure coefficient, k =
0.50) and Case 2, with p,!w, = 1.00 (w. = 10070 vertical projected weight of fill material; k _
1.00). The total vertical load for this condition should be computed as follows:

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