8. Design of Coastal Structures
291
Active pressure (cr£) = (^dryLi + ^'L2)KP + ^'L3{KP - Ka)
= 214.66 kN/m2
Calculation of centre of pressure by taking moment
2
-
YM
1
7 —
_ _ _ — _ _ _ _ _
P
58.32
3
/
2\
/
Q
9.763 0.66 + 3 + - + 29.289 I 0.66 + -
\
*5/
\
2
3
3
/
3\
/
9
+13.151 0.66+ - +6.115 0.66 x -
\
3/
k
3
= 2.23 m.
Calculation of Lx
Summation of ail horizontal forces
EFF = 0
Summation of ail moments at the theoretical depth of sheet pile
SM = 0
Lj + 7.66L4 - I6.65L4 - 151.93L4 - 230.72 = 0
By solving this équation we get, L4 — 4.8 m
Thus,
Dtheory = L3 + L4 = 0.66 + 4.8 = 5.46 m
Part b
The total length of the sheet piles is
Li + L2 + 1.3(L3 + L4) = 2 + 3 + 1.3(5.46) = 12.1 m
Part c
Finally, we hâve the following information.
(2)(58.32)
z
(3.25 - 0.307)(19.33- 9.81)
= 2.04 m
-Mmax
ri
1 z'
= F(T + /)- -^'z'^^Kp - Ka) —
— 209.39 kN-m/m
s —
= 1.217xl0~3m3/m of wall.
^all