渤海海底表层软弱土特征及其对地震动的影响
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摘要
以渤海PL19-3油田工程场地为研究对象,利用钻探和剪切波速实测资料,根据中国规范GB50011-2001、美国规范FEMA-NEHRP和欧洲规范EC8,进行场地类别研究;通过地震动效应分析,得到海底表层软弱土对峰值加速度和反应谱的影响。结果表明,现行规范中的场地土类型划分标准是针对陆地场地土特征的,不能反映覆盖较厚的海底淤泥层的特征;海底表层软弱土对地震动加速度的幅值和频谱的影响非常明显,其对峰值加速度的放大倍数较高,但受土的非线性变形影响,随着地震动输入的增大,其放大倍数呈非线性降低,软土场地使得加速度反应谱谱形变宽,特征周期变大。本文的结果为开展海洋工程抗震标准、海域地震区划研究积累了相关基础资料。
The site of oilfield PL19-3 in Bohai is studied in this paper.According to the Chinese Code GB50011-2001,the America Code FEMA-NEHRP and Europe Code EC8,we use the shear wave velocity and borehole data to study the site classification for soft soil site in Bohai seabed.The site seismic effect is analyzed and the influence of the soft soil of seabed on the design ground motion parameters are discussed.The results show that (1) the site classification in active Codes only fit to the land site,it can't represent the real characteristics of the thicker silt layer of seabed;(2)the soft soil of seabed surface layer puts a remarkable effect on the magnitude and spectrum of the ground motion: the acceleration is magnified significantly due to the nonlinear deformation of the soil and the amplification factor is reduced nonlinearly with the increase of ground motion input;(3)the spectrum is broadened and the characteristic period is extended.The study will put forward the correlate study on the seismic technical codes and design criterion of the oceanic engineering in China.Furthermore,the results of the paper can provide the relate basic data for the seismic design criterion in oceanic engineering and a future seismic zoning of Chinese sea area.
The site of oilfield PL19-3 in Bohai is studied in this paper.According to the Chinese Code GB50011-2001,the America Code FEMA-NEHRP and Europe Code EC8,we use the shear wave velocity and borehole data to study the site classification for soft soil site in Bohai seabed.The site seismic effect is analyzed and the influence of the soft soil of seabed on the design ground motion parameters are discussed.The results show that (1) the site classification in active Codes only fit to the land site,it can't represent the real characteristics of the thicker silt layer of seabed;(2)the soft soil of seabed surface layer puts a remarkable effect on the magnitude and spectrum of the ground motion: the acceleration is magnified significantly due to the nonlinear deformation of the soil and the amplification factor is reduced nonlinearly with the increase of ground motion input;(3)the spectrum is broadened and the characteristic period is extended.The study will put forward the correlate study on the seismic technical codes and design criterion of the oceanic engineering in China.Furthermore,the results of the paper can provide the relate basic data for the seismic design criterion in oceanic engineering and a future seismic zoning of Chinese sea area.
引文
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[5]Building Seismic Safety Council.NEHRPRecommended Provisions for Seismic Regulations forNew Buildings and Other Structures(2003 edition)[S].Washington DC:Building Seismic SafetyCouncil,2004,FEMA 450/451:19-38.
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[7]陈国兴.中国建筑抗震设计规范的演变与展望[J].防灾减灾工程学报,2003,23(1):102-113.Chen G X.The evolution and prospect of the Code forSeismic Design of Buildings in China[J].Journal ofDisaster Prevention and Mitigation Engineering,2003,23(1):102-113.
[8]吕悦军,唐荣余,刘育丰,等.渤海PL19-3油田设计地震动参数研究[J].防灾减灾工程学报,2003,23(4):30-36.L Y J,Tang R Y,Liu Y F,et al.Study on seismicdesign parameters of the oilfield PL19-3 in Bohai[J].Journal of Disaster Prevention and MitigationEngineering,2003,23(4):30-36.
[9]American Petroleum Institute.RP2A-WSD:Planning,Designing,and Constructing FixedOffshore Platforms-Working Stress Design[M].Houston:American Petroleum Institute,2002.
[10]GB 17503-1998,海上平台场址工程地质勘察规范[S].
[11]彭艳菊,吕悦军,唐荣余,等.渤海某油田设计地震动参数及抗震设防标准研究[J].地震工程与工程振动,2007,27(4):8-14.Peng Y J,L Y J,Tang R Y,et al.Research onseismic design parameters and earthquake resistantlevel for an oilfield platform in Bohai Sea[J].Journalof Earthquake Engineering and EngineeringVibration,2007,27(4):8-14.
[2]吕悦军,唐荣余,彭艳菊,等.渤南油田工程地震[M].北京:地震出版社,2003.L Y J,Tang R Y,Peng Y J,et al.EarthquakeEngineering of Offshore Platforms in Southern Bohai[M].Beijing:Seismological Press,2003.
[3]薄景山,李秀领,李山有.场地条件对地震动影响研究的若干进展[J].世界地震工程,2003,19(2):11-15.Bo J S,Li X L,Li S Y.Some progress of study on theeffect of site conditions on ground motion[J].WorldEarthquake Engineering,2003,19(2):11-15.
[4]GB50011-2001,建筑抗震设计规范[S].
[5]Building Seismic Safety Council.NEHRPRecommended Provisions for Seismic Regulations forNew Buildings and Other Structures(2003 edition)[S].Washington DC:Building Seismic SafetyCouncil,2004,FEMA 450/451:19-38.
[6]Eurocode 8,Design of Structures for EarthquakeResistance,Part 1:General Rules,Seismic Actionsand Rules for Buildings,DRAFT No 6[S].Ref.No:prEN 1998—1:200X,CEN:European Committee forStandardization,2003.
[7]陈国兴.中国建筑抗震设计规范的演变与展望[J].防灾减灾工程学报,2003,23(1):102-113.Chen G X.The evolution and prospect of the Code forSeismic Design of Buildings in China[J].Journal ofDisaster Prevention and Mitigation Engineering,2003,23(1):102-113.
[8]吕悦军,唐荣余,刘育丰,等.渤海PL19-3油田设计地震动参数研究[J].防灾减灾工程学报,2003,23(4):30-36.L Y J,Tang R Y,Liu Y F,et al.Study on seismicdesign parameters of the oilfield PL19-3 in Bohai[J].Journal of Disaster Prevention and MitigationEngineering,2003,23(4):30-36.
[9]American Petroleum Institute.RP2A-WSD:Planning,Designing,and Constructing FixedOffshore Platforms-Working Stress Design[M].Houston:American Petroleum Institute,2002.
[10]GB 17503-1998,海上平台场址工程地质勘察规范[S].
[11]彭艳菊,吕悦军,唐荣余,等.渤海某油田设计地震动参数及抗震设防标准研究[J].地震工程与工程振动,2007,27(4):8-14.Peng Y J,L Y J,Tang R Y,et al.Research onseismic design parameters and earthquake resistantlevel for an oilfield platform in Bohai Sea[J].Journalof Earthquake Engineering and EngineeringVibration,2007,27(4):8-14.
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