Cofferdam is a temporary structure builtfor the purpose of excluding or soil sufficiently to permit construction toproceed without excessive pumping, and to support the surrounding ground.
Construction of foundation is most important in a structure,so all the correct and safe actions should be taken while doing a foundation.
Cofferdam is commonly used for oil rig construction and repair, bridge and damwork, the cofferdam is usually a welded steel structure that is temporary andis typically dismantled after work is completed.
Cofferdams is used to provide a safeworking space at foundation level
It’s difficult to handle deep foundationsunder water or ground in deep
Safety in construction of cofferdams
Construction of cofferdam presents safety problemsunique to this type of construction.
They will be limited access, limited workareas, damp or wet footing, and deep excavations.
Provisions must be made for safe access interms of adequate walkways, rails, ladders, or stairs into and out the lowerlevels.
The work may be within a waterway, in whichcase additional safety regulations may apply. These would include provisionsfor flotation devices, boats, warning singles, and suitable means for a rapidexit.
Inside the Barge Gate Cofferdam
Inspection and Maintenance
Dams should be inspected regularly andimmediately repaired if required. Athrough inspection should be conducted following flood events.
Water removed from work area may be siltyand should be discharged to a
vegetated area at least 30 m from thewatercourse, or pumped through a filter bag
The weather forecast should be monitored toanticipate the occurrence of high flow
events. Work operations should be adjusted to accumulate possible overtopping of
the coffer dams
Barge Gate Cofferdam
Considerationof Selection of a cofferdam
Locationof the coffer dam (land/water)
Plansize of working area
Maximumdepth of soil or water to be retained.
Natureof the permanent or floating structure
Effectson excising adjacent structures
Groundwater level & their fluctuation
Availabilityof equipment and material
Possibleconstruction method & dismantling
Effectsof noise, vibration and fumes, & fire risk.
Itwater cofferdam behavior of water.
Cofferdamsis mainly of two types
Gravitycoffer dam :-