8. Design of Coastal Structures
285
Calculation
Calculate coefficient of active earth pressure
Ka = tan2 (45-32/2) = 0.307
Kp = 3.25/2 = 1.625
(As Kp value will not be fully mobilized applying factor of safety 2 to Kp
value.)
Calculating the active earth pressure
Pa (at point O) = (Y x 0 x Ka) — 9.75 xOx 0.307 = 0 kN/m2
Pa (at point E) = (y' x (Hw-H}*Ka} = 1**1* 0.307 = 5.526 kN/m2
P0(at point A) = 5.526 + 20.95 = 26.47 kN/m2
Pa (at point B) = 0 kN/m2
To find a
Pa(@A)=M-i 26.47 = 9.25 x (1.625 - 0.307) x a
a = 2.18 m
Calculating the passive earth pressure
Pp(at point C) = y'ÇKp - Aa) x dl = 12.192dl kN/m2
Calculating Ra and Rp:
Ra = (1/2 x Pa(@E) x (Hw - H)) + (1/2 x Pa(@A) x (Pw)
+ Pa(@E x Hw + 1/2 x Pa(@A x Hw + 1/2 x Pa(@A) x a
= 143.67 kN
Rp = 1/2 x Pp(@C) x dl = 6.26d2
Summation of ail horizontal forces
EFH = 0 = Ra-Rp-T = 0
Summation of ail moments at the tie rod
EM = 0(@ Tie Rod)
= 4.283dl3 + 58.98dl2 - 720.32 = 0