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

Abstract

Stabilizing coral sand foundations presents a considerable challenge in marine and island engineering due to its unique properties. To address the construction demands of "green engineering, ecological islands", this study introduced a novel foundation treatment technology known as the biocemented coral sand pile (BCS pile) composite foundation, which utilized microbially induced carbonate precipitation (MICP) technology as a sustainable alternative to traditional industrial cement. Considering that the combination of long and short piles represents the most economical structural configuration for multi-pile composite foundation, a series of model tests were conducted on the long-short BCS pile composite foundation. The results indicate that the long-short BCS pile composite foundations exhibited a significant improvement in bearing capacity compared to the untreated foundation, thereby validating the feasibility of employing biomineralization for foundation treatment. Additionally, the findings reveal that the load proportion carried by long BCS piles is greater than that of short BCS piles. Moreover, as the cushion layer thickness increased, a higher load proportion was supported by the surrounding sand, leading to a lower pile-soil stress ratio, a diminished load-sharing rate of the BCS piles, and a higher utilization coefficient of bearing capacity. This study demonstrates the potential usage of BCS pile composite foundation in coral sand sites, which is expected to provide valuable guidance for further research and practical applications.