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1. (WO2017022732) JET GROUTING CONSTRUCTION METHOD, GROUND IMPROVEMENT ELEMENT, AND FORMATION STRUCTURE

Pub. No.:    WO/2017/022732    International Application No.:    PCT/JP2016/072568
Publication Date: Fri Feb 10 00:59:59 CET 2017 International Filing Date: Tue Aug 02 01:59:59 CEST 2016
IPC: E02D 3/12
Applicants: NITTO TECHNOLOGY GROUP INC.
株式会社 日東テクノ・グループ
N.I.T. INC.
株式会社エヌ、アイ、ティ
Inventors: OSAWA, Kazumi
大沢 一実
SHINSAKA, Takashi
新坂 孝志
Title: JET GROUTING CONSTRUCTION METHOD, GROUND IMPROVEMENT ELEMENT, AND FORMATION STRUCTURE
Abstract:
[Problem] To provide a construction method with which it is possible to minimize excess portions that exceed an effective wall thickness and with which simple mechanical control is achieved during formation of improvement elements without narrowing the pitch of the improvement elements being formed. [Solution] When a formation structure configured from a plurality of improvement elements is formed by jet grouting, each of the improvement elements is formed such that the cross-sectional shape of the improvement elements is configured in a shape obtained by combining a plurality of types (preferably two to five types) of fan shapes having differing diameters. The cross-sectional shape of the improvement elements: is configured by combining at least two types of small-diameter and large-diameter fan shapes; has small-diameter sections comprising the small-diameter fan shapes and large-diameter sections comprising the large-diameter fan shapes; and has a center angle that is determined on the basis of the fan shapes having the minimum diameter in relation to the effective wall thickness. When the improvement elements are formed, the diameter of the improvement elements is controlled by intermittently varying the rotation speed of the spray tube. In the process, the ground cutting condition due to the jet-grouted improvement elements may be monitored and the diameter of the improvement elements and the effective wall thickness confirmed.