Brief information about Underwater constructions

1. UNDERWATER
CONSTRUCTION

2. what is underwater
construction?

3. introduction
• during the construction of bridges, dams or any other
structure where the foundation part of the structure is
most likely to lie underwater, we have to opt for
underwater construction
• construction in water poses many difficulties especially in
the places where there the depth is considerable

4. activities include
• power generation
• bridges

5. • water utilities
• ship husbandry

6. • industrial
mining pipeline
• power and gas
transmission

7. underwater construction techniques
almost any construction
technique that can be used
abovewater can also be used
underwater

8. underwater construction techniques
There are a number of
products and materials that
have been formulated or
developed specifically for
underwater work

9. underwater construction techniques
•wet construction
&
•dry construction

10. wet construction
• a diver
• evaluate the overall cost of
the work
• considering time
• equipment needs
• the capability of a diver to
accomplish the specific task
• a more gross than fine nature

11. dry construction
caisson
&
cofferdam

12. caisson
•permanent structure
•large hollow structure that sunk down
through the earth
• used in construction of bridge piers,
building columns, dams, repair of ships...
•keeps working environment dry

13. working area of caissons

14. advantages of caisson
•economic
•slight less noise and reduced vibrations
•easily adaptable to varying site conditions
•high axial and lateral loading capacity

15. cofferdams
• temporary structure
• allows enclosed space to be pumped out, creating dry environment
• enclosed coffers are commonly used for construction and repair of oil
platforms , bridge piers and other support structures built within or over
water
• a cofferdam involves the interaction of the structure, soil and water. Loads
imposed include the hydrostatic forces of the water as well as the dynamic
forces due to currents and waves
• used for shallow construction having depth less than 10m.

16. working area of cofferdams

17. advantages of cofferdam
• provides safe environment to work
• contractors have design responsibilty
• steel sheet piles are easily installed and removed
• materials typically reused on other projects

18. placing concrete under water
The satisfactory method of placing concrete underwater is by the use of tremie pipe
• a tremie is a water tight pipe
• generally 250 mm in diameter
• capable of easy coupling for increase or
decrease of length
• Funnel shaped hopper at its upper end and a
loose plug at the bottom
• the concrete having a very high slump of about
15 to 20 cm is poured into the funnel
tremie method

19. placing concrete under water
tremie method
• lifted up and slight jerk is given, so that the
concrete gets discharged
• again concrete is poured over the funnel, the pipe
is slightly lifted amd given jerk
• in this way concrete work is progressed without
stopping till the concrete level comes above the
water level

20. placing concrete under water

21. -pranay kumar
(CVSR colg. of engg.)