METHOD FOR EXCAVATING GROUND UNDER SPREAD FOUNDATION OF EXISTING BUILDING, AND BASE-ISOLATING METHOD FOR EXISTING BUILDING

摘要

PROBLEM TO BE SOLVED: To excavate ground under a spread foundation even without construction of a temporary bearing pile.;SOLUTION: Ground below a footing 24A is excavated in a cylindrical shape while leaving in-envelope ground 47 enclosed with a failure envelope 46, and a foundation section 34 is continuously supported by the cylindrical ground 38A. A cylindrical section 60 is shaped on the outside of the failure envelope 46 of the upper section of the cylindrical ground 38A, and restrained by a ring 50 surrounding the cylindrical section 60. The ring 50 is split in two; a split part is provided with a flange; and the flange is provided with a through-hole for inserting a stopper. After the ring 50 is integrated by the stopper 52, cement 56 is injected into a gap between the ring 50 and the cylindrical section 60 from an injection port 54. The same procedures are repeated; a section from below the footing 24A to an excavated bottom surface 48 is restrained by the plurality of rings 50; and a temporary support section 58 for supporting the foundation section 34 is constructed in a cylindrical shape by an outside diameter of an upper end of the failure envelope 46. Subsequently, the periphery of the temporary support section 58 is supported by a jack, and the temporary support section 58 is removed.;COPYRIGHT: (C)2012,JPO&INPIT