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TYPES OF FOUNDATION 3) WELL FOUNDATION
WELL FOUNDATION Where the loads are heavy Caissons is a type of well foundation Caisson is water tight structure It is made up of R. C. C. , wood and steel R. C. C is used for piers in rivers, bridges and in dock structures. It is constructed in Circular, Square, Octagonal shape. It is also constructed in combination of double circular, double rectangular, double octangle, double hexagonal, double –D in shape.
USES OF CAISSONS Suitable for deep foundation under water When depth of water vis more in river, lake, or in sea, caissons are constructed. Used as a foundation for bridge piers and abutments in rivers, sea, lakes etc. Ocassionally used in large or multistoryed building.
TYPES OF CAISSONS 1) 2) 3) OPEN CAISSON BOX CAISSON PNEUMATIC CAISSONS 1) OPEN CAISSON: - Top and bottom portion is open during construction. - Square or in rectangular in shape - When required depth is reached then bottom is silled with concrete.
1) OPEN CAISSON: Middle portion is filled with sand or gravel Walls are constructed R. C. C. lower portion is filled with concrete It is constructed at any depth or required depth Disadvantage : - slow construction -It is difficult to Silled bottom in concrete Used for foundation of bridges Used on sandy soil and where no firm bed is available single wall open caisson, cylindrical open caisson, open caisson with dredging wells are the types of open caisson
2) BOX CAISSON Open at top and closed at the bottom during construction Bottom is silled when reached at adepth under water It is used where load is not heavy Constructed at shallow depth Mail advantage is that foundation is easily reapair. Casted and cured on ground.
3) PNEUMATIC CAISSON Open at the bottom and closed at the top It is constructed where it is not possible to construct a well. Suitable for a depth of water more than 12 m Made up of timber, concrete or steel Compressed air is used to removed water from chamber and Foundation work is done under dry condition.