LIQUEFACTION COUNTERMEASURE CONSTRUCTION METHOD OF UNDERGROUND STRUCTURE

PROBLEM TO BE SOLVED: To provide a liquefaction countermeasure construction method of an underground structure, efficiently executable at low cost even in a narrow place when an underground buried facility interferes, by preventing floating of the underground structure in liquefaction time.SOLUTION: An improvement body 2 small in an improvement diameter S is constructed up to reaching a non-liquefaction layer 6 in a column row shape along both sides in the extension direction of an underground structure 1 by a high pressure injection agitation method, and a ground improvement composite wall 4 of continuing a composite pile composed of the improvement body 2 and a core material 3 is established by repeating a process of building up the core material 3 in the inside of the improvement body 2, and a drain material 5 is installed in a trace of boring a contact circle part near the underground structure 1 of the adjacent composite pile of revealing predetermined strength.SELECTED DRAWING: Figure 1 【課題】液状化時の地中構造物の浮き上がりを防止し、地中埋設物が干渉する場合や狭隘な場所でも効率よく低コストで施工できる地中構造物の液状化対策工法を提供する。【解決手段】地中構造物１の延長方向両側に沿って、高圧噴射撹拌工法で改良径Ｓの小さい改良体２を柱列状に非液状化層６へ到達するまで構築し、前記改良体２の内部に芯材３を建て込む工程を繰り返し行うことにより、前記改良体２と芯材３とからなる合成杭を連続させた地盤改良合成壁４を造成すると共に、所定の強度を発現した隣接する前記合成杭の前記地中構造物１寄りの接円部分をボーリングした跡にドレーン材５を設置する。【選択図】図１