Jet grouting is a technique for ground improvement which employs high pressure cement slurry and high pressure air. Because of the high energy with which the cement slurry is injected into the ground, the soil structure breaks up and mixes with the soil particles in situ, creating a high-strength soilcement material. However, this creates a large amount of industrial waste during construction, which is a problem because of the effect on construction costs and environmental factors. Based on this background, a new jet grouting method (the MultiFan method) for wall-form ground improvements was developed in order to reduce the amount of redundantly improved soil. This method is comprised of partially formed, fan-shaped columns. In this paper, we geometrically examined the effectiveness of the MultiFan shape column for wall-form ground improvement. The effectiveness of the MultiFan column was verified by comparing it with round and oval columns created by conventional jet grouting methods. Consequently, the ground improvement work utilizing the MultiFan columns could be carried out more effectively than round or oval shapes. In addition, we developed a new control device for this method of ground improvement and conducted field tests to confirm its workability and quality. Consequently, we were able to confirm our assumption that it is possible to construct MultiFan shape columns for ground improvement work. Furthermore, core borings were carried out and column strength and variation were confirmed by uniaxial compression tests. The results showed that there was almost no difference in strength between the large diameter part and the small diameter part of the fans, and the variation was small. Therefore, it was confirmed that a homogeneously improved soil body could be produced by the MultiFan shape jet grouting method.
Subjects: None provided
Author: Takashi Shinsaka, Dr.Eng, P.E.jp, Sen.Pro.C.E, Junichi Yamazaki, P.E.jp, Yasuharu Nakanishi and Kazuhito Komiya, Prof.
Publisher: DFI, EFFC