Study on Spoil Reduction Discharged by Jet Grouting Method in Clayey Soils

Abstract

The high-pressure jet grouting is a soil improvement method in which liquid solidification materials are jetted into the ground at high speed and mixed and agitated with the soil to form a solid body. Since it is necessary to cut the ground and mix and agitate with the cement slurry to be jetted, the amount of injection (≒spoil volume) is larger than that in the mechanical mixing method. In response to this problem, the authors conducted an in-situ construction experiment on a sandy soil by using a fluidizing agent for high-pressure jet grouting and a low-volume injection method, and reported in a previous paper that the spoil volume could be reduced by about 30% compared with the conventional method. In this study, we examined the use of a fluidizing agent in combination with an auxiliary agent and the injection specification to reduce spoil mass, targeting clayey soil, which has a high risk of spoil blockage and soil mass residuals due to its low injection rate compared with sandy soil. In this study, we showed that the spoil volume could be reduced by about 20% while securing the workability and construction quality equivalent to the conventional method in the in-situ construction experiment.