CONSTRUCTION METHOD FOR PREVENTING INNER PACKING OF CAISSON FROM RUNNING OUT

PROBLEM TO BE SOLVED: To allow inexpensive construction, and to prevent inner packed sand from running out even when a caisson is damaged. SOLUTION: When the inner packing sand 5 is filled into a hollow inside of the concrete caisson 2 to form inner packing, the sand is filled after concrete 10 of low compression strength of such a degree as allowing self-support when cured, using a regenerated aggregate such as coal ash instead of a fine aggregate, is placed on the inside of the outermost wall 2a of a caisson main body. In the concrete 10 of low compression strength, a ration of water to cement is 100-200%, a slump flow is 550-650 mm, the coal ash instead of the fine aggregate is used as a rate of 300-500 kg/m3, and compression strength is several N/mm2 when cured.