PROBLEM TO BE SOLVED: To provide a piled-raft foundation with superior earthquake resistance without improving a ground.;SOLUTION: In this piled-raft foundation 10, a structure 12 is constructed on a soft ground 16. The soft ground 16 is a soft viscous soil ground in a normal consolidation state or in a state near that state in which consolidation settlement is produced by the weight W of the structure. The soft ground 16 is not improved. The base of the structure 12 is a direct base 14, and first piles 22 are embedded just beneath the columns 28 of the structure 12. The first piles 22 are cast-in-place concrete piles, PHC piles, or steel tube piles, and have a length reaching a hard support ground 20, and the bottom ends of the piles are embedded into the support ground 20. Second piles 24 are embedded into the lower surfaces of the slabs and beams of the direct base 14. The second piles 24 are PHC piles or steel tube piles, and have a length reaching an excessively consolidated ground 18 with less consolidation settlement, and the bottom ends of the piles are embedded into the excessively consolidated ground 18. The length of the second piles 24 is shorter than that of the first piles 22.;COPYRIGHT: (C)2010,JPO&INPIT
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