A NOVEL Q-z MODEL TO DESCRIBE PILE TIP ACCUMULATED DISPLACEMENT

Li Wei; Zhou Wenjie

doi:10.19912/j.0254-0096.tynxb.2020-0916

PDF(2610 KB)

Acta Energiae Solaris Sinica ›› 2022, Vol. 43 ›› Issue (6) : 219-225. DOI: 10.19912/j.0254-0096.tynxb.2020-0916

A NOVEL Q-z MODEL TO DESCRIBE PILE TIP ACCUMULATED DISPLACEMENT

Li Wei, Zhou Wenjie

Author information +

History +

Abstract

Offshore wind power is a deformation-sensitive structure, and the jacket foundation offshore wind power structure will bear large vertical cyclic loads during its service period. For analyzing and calculating the vertical load of the pile foundation, ABAQUS is used to analyze the influence zone of the pile tip. Based on the strain accumulation characteristics of sand in dynamic triaxial test, a novel Q-z model is proposed. Compared with traditional Q-z model, this novel model can use several parameters to simulate the behavior of displacement accumulating at the pile tip under axial cyclic loadings. Combined with the finite element software COMSOL, the secondary development is carried out to simulate the axial cyclic loading condition of single piles. The model validation is conducted with centrifuge tests of single pile under axial cyclic loadings. In the numerical simulation, the pile-soil interaction model (p-y) in the American Petroleum Institute （API） standard, the elastoplastic t-z model that considers the cyclic degradation of strength and stiffness in the pile-soil interface, and the novel Q-z model which can describe the pile tip accumulated displacement is adopted respectively to analyze the responses of offshore substation under cyclic loadings, which provide useful suggestions for the design of offshore substation.

Key words

offshore wind power / pile / axial cyclic loadings / Q-z model / offshore substation

Cite this article

EndNote

Ris (Procite)

Bibtex

Download Citations

Li Wei, Zhou Wenjie. A NOVEL Q-z MODEL TO DESCRIBE PILE TIP ACCUMULATED DISPLACEMENT[J]. Acta Energiae Solaris Sinica. 2022, 43(6): 219-225 https://doi.org/10.19912/j.0254-0096.tynxb.2020-0916

References

[1] 林楚. 海上风电坐稳世界第三＂十三五＂目标有望完成[J]. 电力系统装备, 2017(9): 18-21.
LIN C.The goal of stabilizing offshore wind power in the 13th five-year plan is expected to be fulfilled[J]. Equipment electric power system equipment, 2017(9): 18-21.
[2] DET NORSKE VERITAS.Design of offshore wind turbine structures: DNV-OS-J101[S].
[3] 周文杰, 王立忠, 汤旅军, 等. 导管架基础海上风机动力响应数值分析[J]. 浙江大学学报(工学版), 2019,53(8):1431-1437.
ZHOU W J, WANG L Z, TANG L J, et al.Numerical analysis of dynamic responses of jacket supported offshore wind turbines[J]. Journal of Zhejiang University(engineering science, 2019, 53(8): 1431-1437.
[4] POULOS H G, HARRY G.Cyclic axial loading analysis of piles in sand[J]. Journal of geotechnical engineering, 1989, 115(6): 836-852.
[5] RANDOLPH M F.Ratz-load transfer analysis of axially loaded piles[M]. 2nd ed. Perth: The University of Western Australia, 2003.
[6] LI Z M, BOLTON M D, HAIGH S K.Cyclic axial behavior of piles and pile groups in sand[J]. Canadian geotechnical journal, 2012, 49(9): 1074-1087.
[7] POULOS H G, CHUA E W.Bearing capacity of foundations on calcareous sand[C]//International Conference on Soil Mechanics ＆ Foundation Engineering, San Francisco,CA, USA, 1985.
[8] American Petroleum Institude.API RP 2A-WSD-2014, Recommended practice for planning, designing and constructing fixed offshore platforms-working stress design[S].
[9] ZHOU W J, WANG L Z, GUO Z, et al.A novel t-z model to predict the pile responses under axial cyclic loadings[J]. Computers and geotechnics, 2019, 112(8): 120-134.
[10] WANG L Z, ZHOU W J, GUO Z, et al.Frequency change and accumulated inclination of offshore wind turbine jacket structure with piles in sand under cyclic loadings[J]. Ocean engineering, 2020, 217: 1082045.
[11] MOSHER R L.Load-transfer criteria for numerical analysis of axially loaded piles in sand[R]. Final Report Army Engineer Waterways Experiment Station, Vicksburg, MS.K-84-1,1984.
[12] DOLWIN R, RANDOLPH M F, BECK R.Design of driven piles in sand[J]. Geotechnique, 1994, 44(3): 427-448.
[13] CLAUSEN C J F, AAS P M, KARLSRUD K. Bearing capacity of driven piles in sand,the NGI approach[C]//Proceedings of 1st International Symposium on Frontiers in Offshore Geotechnics, Perth, Australia, 2005.
[14] ZHANG Y H, JEANJEAN P, KARLSRUD K, et al. Validation of monotonic and cyclic p-y framework by lateral pile load tests in stiff, over consolidated clay at the Haga site[J]. Journal of geotechnical and geoenvironmental engineering, 2020, 146(9): 04020080/1-04020080/14.
[15] 任宇. 长期竖向循环荷载作用下桩的变形特性试验及理论研究[D]. 杭州: 浙江大学, 2013.
REN Y.Model test and theoretical study on the deformation behavior of single piles on long-term cyclic axial loading[D]. Hangzhou: Zhejiang University, 2013.
[16] YANG J, ASCE M.Influence zone for end bearing of piles in sand[J]. Journal of geotechnical & geoenvironmental engineering, 2006, 132(9): 1229-1237.
[17] 张宏博. 长期往复荷载作用下无粘性材料累积变形研究[D]. 上海: 同济大学, 2006.
ZHANG H B.Long term cumulative deformation of cohesionless material induced by repeated loading[D]. Shanghai: Tongji University,2006.
[18] 王磊. 福建标准砂加筋硬化与循环累积变形三轴试验及本构模型[D]. 杭州: 浙江大学, 2014.
WANG L.Triaxial testing and constitutive modeling for fiber reinforcement and cyclic accumulative strain of Fu Jian sands[D]. Hangzhou: Zhejiang University, 2014.
[19] RANDOLPH M, WROYH C.Analysis of deformation of vertically loaded piles[J]. Journal of geotechnical and geoenvironmental engineering, 1978, 104(12): 1465-1488.
[20] JALBI S, NIKITAS G, BHATTACHARYA S, et al. Dynamic design considerations for offshore wind turbine jackets supported on multiple foundations[J]. Marine structures, 2019, 67(9): 102631/1-102631/20.