Abstract
This paper discusses the reduction and subsequent recovery and increase of shear strength of clay in the vicinity of soil-cement column. Laboratory and field tests were conducted to investigate the effects on surrounding clay during and after column installation in soft Ariake clay. Discussions were made on the mechanism of strength change of the surrounding clay by considering the thixotropic recovery, reconsolidation effect, penetration of cement slurry and diffusion of exchangeable rations after construction. On the basis of field observation, it is recommended that the increase of shear strength of clay can be taken into consideration in the bearing capacity and stability analysis of the composite ground.
