考虑桩周土体的海上风电大直径单桩变径体系1阶频率研究
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摘要
海上风电大直径单桩体系1阶频率对风电结构的设计和使用至关重要。为研究以上问题,以4 MW风力机为例根据场地实测土层参数,分别建立未考虑环境水体和考虑环境水体的3种有限元模型,利用激振法测出以上有限元模型的1阶频率并发现:考虑桩周土体后体系1阶频率增大,环境水体对体系1阶频率影响较小。针对以上现象提出一种考虑桩周土体的海上风电大直径单桩变径体系1阶频率量化方法。新方法计算结果与有限元方法计算结果对比表明:2种方法计算结果具有一致性,在初步设计时可利用新的量化方法。
Offshore wind turbines large diameter single pile system first order frequency is crucial for design and utilization of wind power structure;to research the above problem,4 MW turbine is taken as example to establish three finite element models without and with consideration on environmental waters according to measured soil layer parameter onsite. Shock excitation method is adopted to measure the first order frequency of the above mentioned finite element models and it is found that:with consideration on soil mass around the pile,the first order frequency of the system reduces;environmental water has small influence on the first order frequency of the system. Aiming at the above mentioned phenomenon,an offshore wind turbines large diameter single pile system first order frequency quantitative method with consideration on soil mass around the pile is brought forward. The comparison between calculation results of the new method and finite element method indicates that:calculation results of the two methods have consistency and new quantitative method can be used in preliminary design.
Offshore wind turbines large diameter single pile system first order frequency is crucial for design and utilization of wind power structure;to research the above problem,4 MW turbine is taken as example to establish three finite element models without and with consideration on environmental waters according to measured soil layer parameter onsite. Shock excitation method is adopted to measure the first order frequency of the above mentioned finite element models and it is found that:with consideration on soil mass around the pile,the first order frequency of the system reduces;environmental water has small influence on the first order frequency of the system. Aiming at the above mentioned phenomenon,an offshore wind turbines large diameter single pile system first order frequency quantitative method with consideration on soil mass around the pile is brought forward. The comparison between calculation results of the new method and finite element method indicates that:calculation results of the two methods have consistency and new quantitative method can be used in preliminary design.
引文
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[9]柳国环,练继建,王鸿振,等.水动力质量实效施加方法及地基-筒型基础-塔筒体系的地震敏感性研究[J].岩土力学,2016,37(3):767—775.[9] Liu Guohuan,Lian Jijian,Wang Hongchen,et al. A practical method for applying the hydrodynamically induced mass and the sensitivity analysis of the groundbucket foundation-tower system[J]. Rock and Soil Mechanics,2016,37(3):767—775.
[10] Poulos H G,Davis E H. Pile foundation analysis and design[M]. Taipei:Hongqiao Bookstore Co., Ltd,1980,166—174.
[2] Darvishi-Alamouti S,Bahaari M R,Moradi M. Natural frequency of offshore wind turbines on rigid and flexible monopiles in cohesionless soils with linear stiffness distribution[J]. Applied Ocean Research,2017,68:91—102.
[3] Karimirad M. Offshore energy structures:for wind power,wave energy and hybrid marine platforms[M].Switzerland:Springer,2014.
[4] Arany L,Bhattacharya S,Macdonald J H G,et al.Closed form solution of Eigen frequency of monopile supported offshore wind turbines in deeper waters incorporating stiffness of substructure and SSI[J]. Soil Dynamics and Earthquake Engineering,2016,83:18—32.
[5] van der Tempel J, Molenaar D P. Wind turbine structural dynamic-a review of the principles for modern power generation, onshore and offshore[J]. Wind Engineering,2002,26(4):211—222.
[6]刘晶波,杜修力.结构动力学[M].北京:机械工业出版社,2005,112—117.[6] Liu Jingbo, Du Xiuli. Dynamics of structures[M].Beijing:China Machine Press,2005,112—117.
[7]冯世进,王雷.锤击荷载作用下大直径钢管群桩的动力特性分析[J].岩土工程报,2017,39(1):129—137.[7] Feng Shijin,Wang Lei. Dynamic response analysis of a large-diameter steel tube pile group subjected to hammering loads[J]. Chinese Journal of Geotechnical Engineering,2017,39(1):129—137.
[8] Depina I,Le T M H,Eiksund G,et al. Behavior of cyclically loaded monopile foundations for offshore wind turbines in heterogeneous sands[J]. Computers and Geotechnics,2015,65:266—277.
[9]柳国环,练继建,王鸿振,等.水动力质量实效施加方法及地基-筒型基础-塔筒体系的地震敏感性研究[J].岩土力学,2016,37(3):767—775.[9] Liu Guohuan,Lian Jijian,Wang Hongchen,et al. A practical method for applying the hydrodynamically induced mass and the sensitivity analysis of the groundbucket foundation-tower system[J]. Rock and Soil Mechanics,2016,37(3):767—775.
[10] Poulos H G,Davis E H. Pile foundation analysis and design[M]. Taipei:Hongqiao Bookstore Co., Ltd,1980,166—174.