Pile groups using steel pipe piles with wings are often constructed to support large-scale buildings. Soil around these piles is known to be loosened during construction. Therefore, to reasonably design pile groups using steel pipe piles with wings, it is necessary to investigate the pile group effects considering loosened soil around pile shafts. We conducted in-situ lateral loading tests on both single pile and two-pile groups with/without wings and discussed the differences in lateral soil resistances of their piles.
