Load-bearing characteristics of concrete-filled steel tubular combined piles (CFSTCPs) in sand-rock composite ground

• Published in: Ocean engineering Vol. 288; p. 116062
• Main Authors: Wang, Qinke, Hu, Zhongbo, Zhao, Guoliang, Zhu, Baolong, Wang, Yaorui
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15-11-2023
• Subjects: Concrete-filled steel tubular combined pile; Load-bearing characteristics; Model experiments; Offshore wind power; Sand-rock composite ground; Load-bearing characteristics; Sand-rock composite ground; Offshore wind power; Concrete-filled steel tubular combined pile; Model experiments
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2023.116062

Novel concrete-filled steel tubular combined piles (CFSTCPs) have been widely used in offshore wind power projects in Fujian, China. The bearing capacity of their foundations has become a particular concern in the offshore wind power industry. However, experiments to understand the bearing performance of CFSTCPs in sand-rock composite ground remain few. In this study, a series of model experiments were conducted to investigate the load-bearing characteristics of CFSTCPs in sand-rock composite ground, and evaluate the effects of the rock-socketed length and uniaxial compressive strength (UCS) of the bedrock. Moreover, the accuracy and regularity of the test results were verified through numerical testing. The results showed that the load-settlement curve of the CFSTCP exhibited the failure pattern of “continuous and gradual, without obvious inflection point.” When the ultimate load was reached, interface sliding occurred between the steel pipe and sand. The pile tip penetrated the bedrock, resulting in penetration failure. The dimensionless relationship between the bearing ratio of the pile-tip resistance, rock-socketed length, and bedrock UCS was obtained to determine the critical rock-socketed length. Finally, an empirical method for calculating the ultimate bearing capacity of CFSTCPs was proposed. These findings promote the design of CFSTCPs for offshore wind turbine foundations.
•The load-bearing characteristics and failure mode of CFSTCPs in the sand-rock composite ground are revealed through model tests.•The dimensionless relationship between ζb and lr and σc is derived to evaluate the critical rock-socketed length.•An empirical method for calculating the ultimate bearing capacity of CFSTCPs in the sand-rock composite ground is proposed.