To provide an economical and rational countermeasure construction method against the liquefaction of under ground supporting an existing structure capable of forming a diaphragm wall having a substantially trapezoidal vertical section by designing an injection solidification method for the under ground supporting the existing structure (soft ground such as sandy ground).
The diaphragm wall 4 having a substantially trapezoidal vertical section the width of which is gradually reduced from a deep layer toward a shallow layer is formed in the under ground 3 supporting the existing structure 1 by repeatedly performing a process for drilling under ground 3 supporting the existing structure 1 at a fixed inclination angle by a boring machine type ground improving machine 2 installed at a position adjacent to the existing structure 1, and forming one or a plurality of ground improving bodies 4a in the axial direction of the drilled part while successively changing the axial angle.
KON NOBUAKI
KAWASAKI TETSUTO
UCHIDA AKIHIKO
HIRAKAWA YASUAKI
TAKENAKA KOMUTEN CO