Abstract
The sand compaction piles are often applied in order to improve a poor ground in Japan. The very soft clay layer under a sea inevitably heaves by driving the sand compaction piles in the ground. Since the removal of an upheaved part brings a high cost and a muddy water, it is strongly demanded to utilize the upheaved part as a foundation of structures. This paper discribes the results of a proto-type field test in a sea. The generating mechanism of the upheaved ground and its shape by the sand compaction piles are shown with the soil properties. The shear strength of the upheaved ground increases with the effect of the sand piles for drain wells. The deformation characteristics and stability of the upheaved ground are investigated by a field loading test. The loading control method to construct the structure safely on the upheaved ground is also proposed.
