METHOD FOR IMPROVING GROUND DIRECTLY UNDERNEATH EXISTING STRUCTURE

• Main Authors: NEGISHI YASUAKI, SATAKE OSAMU, SUZUKI AKIHIKO, OKADO MASANORI, ITO TAKESHI, TANAKA HATSUICHI, HAMADA RYUICHI, AKIMA TAKESHI, TASHIRO KATSUMI
• Format: Patent
• Language: English; Japanese
• Published: 21.12.2017
• Subjects: EMBANKMENTS; EXCAVATIONS; FIXED CONSTRUCTIONS; FOUNDATIONS; HYDRAULIC ENGINEERING; SOIL SHIFTING; UNDERGROUND OR UNDERWATER STRUCTURES

PROBLEM TO BE SOLVED: To enable an existing structure such as a road on which a vehicle travels to return to service promptly when a ground directly underneath the existing structure is improved by forming a solidified improvement body in the ground.SOLUTION: A method to improve a ground directly underneath an existing structure is for improving the ground by forming a solidified improvement body in the ground directly underneath the existing structure, and includes the following steps for: forming a solidified improvement body T in the ground in an upward direction, by inserting a pipe rod 1 into a prescribed depth from a ground surface, and then injecting cement milk M that is a hardener from a tip of the pipe rod 1, and mixing-agitating with the ground, the mixing-agitation between the injected cement milk M and the ground being performed while pulling up the pipe rod 1; and inputting the quick hardening material S into a top layer portion or a part above a top edge of the solidified improvement body formed in the previous step, for promoting hardening of the cement milk M that is the hardener, and promoting hardening of the hardener using a quick hardening material S.SELECTED DRAWING: Figure 7 【課題】車両が通行する道路などの既設構造物直下の地盤中に固結改良体を造成して地盤を改良するとき、既設構造物を早期に使用できるようにする。【解決手段】既設構造物直下の地盤中に固結改良体を造成して地盤を改良する既設構造物直下の地盤改良方法であって、管ロッド１を地表面から所定の深度まで挿入し、挿入後、管ロッド１の先端から硬化材であるセメントミルクＭを地盤中に噴射して地盤と混合攪拌し、噴射したセメントミルクＭと地盤との混合攪拌を管ロッド１を引き抜きながら行って地盤中に上方に向かって固結改良体Ｔを造成する工程と、前記工程において造成した固結改良体の上層部分又は固結改良体の上端より上の部分に、硬化材であるセメントミルクＭの硬化を促進する早強材Ｓを投入し、早強材Ｓによって硬化材の硬化を促進させる工程と、を有する。【選択図】図７