Study on bearing characteristic of multi-pile composite foundation with biocemented coral sand pile

The treatment of coral sand foundation is a key challenge faced by marine or island engineering owing to its unique properties. In order to meet the construction requirements of "green engineering, ecological islands", an innovative foundation treatment technology, termed as biocemented coral sand pile (BCS pile) composite foundation, was proposed in this study by using MICP technology instead of industrial cement. A series of model tests were conducted to examine the influence of area replacement rate (ARR) on the bearing characteristics of long-short BCS pile composite foundations, and the load-settlement relationship, axial force, side friction, loadsharing ratio, and pile-soil stress ratio were analysed. Results shown that the new foundation treatment technology improved the bearing capacity of coral sand foundation by 12.7 %-67.73 %. Additionally, the axial force, pile-soil stress ratio, and load-sharing ratio for long BCS piles were approximately double those of short BCS piles. The bearing capacity of BCS pile was underutilized in the multipile composite foundation, and the group-pile effect led to an increase in the pile-soil stress ratio. The study demonstrates the potential usage of BCS pile composite foundation in coral sand sites, which was expected to provide valuable guidance for further research and practical applications.