EM 1110-2-1100 (Part III)
30 Apr 02
Example Problem III-2-12 (Concluded)
For times beyond the 3-month initial fill placement and maintenance, a solution of the form of
Equation 2-39 must be utilized. In this particular case, the solution would be of the form (where Yo
= 50 m, Y1 - Yo = 50 m, and t1 = 3 months):
x
x
y(x, t) ' Yo @ erfc
% (Y1 & Yo) @ erfc
2 εt
2 ε (t & t1)
which can be reformulated to be:
x
x
1
@
y(x, t) ' 50 @ erfc
% 50 erfc
2 εt
2 εt
t1
1&
t
' term 1
term 2
%
The solution is provided in the table below:
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
x
&1/2
t1
t
y
erfc((2))
erfc((3))
term 1
term 2
(2) @ 1&
2 εt
t
0.90
0.90 (1.414)
0.20
0.07
10.0
3.5
13.5 m
6 mo.
= 15.8 106 sec.
= 1.27
0.73
0.73 (1.225)
0.30
0.21
15.0
10.5
25.5 m
9 mo.
= 23.7 106 sec.
= 0.89
0.63
0.63 (1.155)
0.37
0.30
18.5
15.0
33.5 m
12 mo.
= 31.6 106 sec.
= 0.73
Note that the solution form assumes that the fill is constantly maintained at its design width. This
would probably not be achievable in practice, and solutions would have to be modified in accord
with good engineering judgment.
Longshore Sediment Transport
III-2-77
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