8. Design of Coastal Structures
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by wave should be maintained.
Mr
M
, _ mr
1.5 i.e., M
WBIÏ
_____ L___ — q
1 k
620 x 6.5 3 > 1,5
Hence the structure is safe against overturning.
Problem IX
Design a diaphragm wall capable of holding the land and water apart
through a combination of its own mass with the passive résistance of the
ground forming the seabed immediately in front of it. Consider the following
parameters for design: Grade of concrète = M35, Grade of Steel = Fe500,
Clear cover — 75 mm, Angle of internai friction = 38°, Dry unit weight of
soil = 19.5 kN/ m2, Saturated unit weight of soil = 20.5 kN/m2, Submerged
unit weight of soil = 9.5 kN/m2, Surcharge live load = 30 kN/m2, Active
earth pressure coefficient (fca) = 0.237, Passive earth pressure coefficient
(fc ) = 4.2. Consider the berthing load as 100 kN/m and mooring load as
15 kN/m. The height of the wall needs to be maintained at 6.8 m. Also
estimate the tension in tie rod to be placed at 1.5 m from top level of quay
wall.
Solution
The dimensions of the wall are assumed as given in the drawing.
BERTHING LOAD
—►
SURCHARGE LOAD *“
PRESSURE DUETO —►
WATER
DIMENSIONS OF DIAPHRAGM WALL
LOAD ACT1NG DIRECTIONS
4— ACTiV E EARTH
PRESSURE
<— SURCHARGE LOAD
PASSIVE
PRESSURE