夏季工况下正常服役地热能源桩承载性能原位试验研究

doi:10.13722/j.cnki.jrme.2020.0858

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Abstract Understanding the bearing behavior of geothermal energy piles in natural service will help researches in theory and design method，and provide evidence for safety assessment. A pile-loading field test for static drill rooted geothermal energy piles(SDRGEP) was undertaken to investigate the working mechanism of the piles in service under temperature cycles. In a SDRGEP of 52 m depth，the fiber bragg grating(FBG) sensors(including strain，stress and temperature) were buried to measure the temperatures of the pile and the surrounding soil，the mobilized axial and radial stresses and strains of the pile，the shaft resistance，etc. Test results show that，after heating of 14 d，the heat exchanging system reaches a stable state and the average temperature of the pile is raised by 15.8 ℃ with a distribution of low in middle and high at both ends and an influence range of 2 to 4 times of the pile radius. It is also found that the relationships of both the mobilized radial stress and the mobilized axial stress with the temperature are linear，with maximum fitting gradients of 0.014 MPa/℃ at 0.86 times of the pile length and 0.3 MPa/℃ at 3.05 m depth respectively. The mobilized shaft resistance first increases and then decreases with the depth，reaching the maximum value at 0.649–0.861 times of the pile length. Whilst the pile head is fully constrained，the null point locates at the pile top and there is no negative side shear stress along the pile，showing that the bearing capacity of the pile is closely related to the constraint of the pile head. The maximum axial force at the pile head is 1 954 kN under the mechanical and thermal loads，which is only 42.5% of the ultimate bearing capacity of the pile，indicating that the pile is safe.

Key words： pile foundation geothermal energy piles fully constraint on pile top static drill rooted piles in-situ test summer condition

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	Articles by authors
	FANG Pengfei1
	2
	GAO Xiang3
	LOU Yang3
	ZHANG Rihong4
	XIE Xinyu3
	WANG Zhongjin1
	2
	ZHU Dayong1
	2

Cite this article:

FANG Pengfei1,2,GAO Xiang3, et al. Field test on the bearing behaviors of geothermal energy piles in natural service under the summer condition[J]. , 2021, 40(5): 1032-1042.

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http://rockmech.whrsm.ac.cn/EN/10.13722/j.cnki.jrme.2020.0858 OR http://rockmech.whrsm.ac.cn/EN/Y2021/V40/I5/1032

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