FLOATING DOCK FOR CONSTRUCTING CAISSON

PURPOSE:To reduce the size of a dock, lower working position, reduce the cost, and improve safety, by a method wherein side tanks, on which crane devices are respectively loaded, are vertically movably located on both sides of a bottom tank, and the buoyance of a dock is made adjustable. CONSTITUTION:A caisson 21 is built on a bottom tank 1 after lowering side tanks 13 to the lowermost position. As the height of the caisson 21 increases with the progress of construction, the side tanks 13 are raised along guide struts 11, and the upper part of the caisson 21 is allowed to slightly emerge from the sea surface W by pouring water into the bottom tank 1 so that construction work is practicable. After the caisson 21 is completed, water is further poured into the bottom tank 1 to sink the tank in order to provide a condition in which the caisson 21 slightly floats away from the tank 1 with the buoyancy of the caisson itself. Then, the side tanks 13 are further raised to the upper part of the strut 11. The caisson 21 is pulled out of a dock under this condition and tugged. This causes the dock to support a weight less the buoyancy of the caisson, resulting in the ability to reduce the size of the dock, lower working height, and reduce the cost.