292
Coastal Engineering: Theory and Practice
Problem XII
A steel pipe pile of 61 cm outside diameter with 2.5 cm wall thickness
is driven into saturated cohesive soil to a depth of 20 m; the undrained
cohesive strength of the soil is 150 kPa (Soil is over Consolidated clay).
The interior of the pile is filled with M35 mass concrète to add stiffening. The pile is subjected to a latéral load of 268 kN at a height of 2 m
above the ground level. Calculate the depth of fixity and the deflection of
the pile.
Assume:
E8teei(£s) = 208 x 103 MN/m2
EConcrete(£C) = 20 X 103 MN/m2
Solution
To find El:
Steel:
_ tv(D4 - d4) _ 7t[(0.61)4 - (0.56)4]
IÇsteel) -
64
-
64
= 1.96 x 10~3m4
EI{steel) = (208 x 103)(1.96 x 10~3) = 407.68 MN/m2
Concrète:
,
ivd4
7f(0.56)4
t n
4
^(concrète) — „a =
~ 4.8 X 10 m
'
64
64
El^concrete') = (20 x 103)(4.8 x 10~3) = 96 MN-m2
El = El(steeZ) + EZ(concrete) = 503.68 MN-m2
To find the deflection of pile, it is désirable to know the modulus of subgrade
reaction (Kh). The modulus of subgrade reaction and stiffness factor are
based on the concept of Terzaghi, for more details readers are advised to
refer Tomlinson (1994).
0.3
B