Abstract
In Sand Compaction Pile method, when the vibroflot is inserted into a saturated clay layer, the clays around the sand pile are disturbed and even outside the improved area the excess pore water pressure is generated and the shear strength of clay decreases. In this paper, based on the laboratory test results including the multi-directional simple shear tests for undisturbed samples, the effects of the disturbance by the SCP driving operations on the shear strength of clay outside the improved area and the border of the region affected by the SCP driving are investigated. In conclusion, it is clarified that the shear strength of clay decreases immediately after the SCP driving and the border of the disturbed region is given by the surface of sliding under the passive earth pressure condition.
