用震级和距离参数修正土层反应的等效线性化方法
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摘要
传统等效线性化波动法主要的缺陷之一,是当基岩输入地震动较强时,高频段算得的频响放大倍率比实际场地的实测结果明显偏低.该缺陷可能导致低估重大工程的设计地震动参数的严重后果,因而是亟待解决的重要问题.本文认为,现行基于土的剪切模量和阻尼比的频率相关性修正等效剪应变的做法有其合理性,但不便应用并可能具有较大的不确定性;由于震级可以影响地震动的频谱特征,通过震级调整等效剪应变的做法也可视为按照频率调整等效剪应变.由于距离与震级一样也可以影响地震动的频谱特征,本文提出通过震级M和距离R参数修正等效线性化的方法EQLM(M,R),并用算例说明,等效线性化方法的上述缺陷可以通过本文提出的EQLM(M,R)方法得到一定程度的改善.
One of important shortcomings of the traditional equivalent linear method (EQLM)is that for large input motions the magnification of high frequency components calculated is obviously lower than that observed.The defect may lead to a serious result of underestimating design ground motion parameters for key projects.So this important issue needs to be solved.Although it is reasonable to improve EQLM by using frequency-dependent modules and damping ratios,it is not convenient to use and has great uncertainties.This article points out that,because magnitudes can affect spectra of ground motion,the method to improve EQLM by adjusting equivalent shear strain based on magnitudes may also be regarded as frequency-dependent.Since distance can also affect the spectra,we suggest a method EQLM(M,R) to improve EQLM by the parameters of magnitudes and distances.An example of EQLM(M,R) is given to show that the above-mentioned shortcoming of EQLM can be resolved to some extent.
One of important shortcomings of the traditional equivalent linear method (EQLM)is that for large input motions the magnification of high frequency components calculated is obviously lower than that observed.The defect may lead to a serious result of underestimating design ground motion parameters for key projects.So this important issue needs to be solved.Although it is reasonable to improve EQLM by using frequency-dependent modules and damping ratios,it is not convenient to use and has great uncertainties.This article points out that,because magnitudes can affect spectra of ground motion,the method to improve EQLM by adjusting equivalent shear strain based on magnitudes may also be regarded as frequency-dependent.Since distance can also affect the spectra,we suggest a method EQLM(M,R) to improve EQLM by the parameters of magnitudes and distances.An example of EQLM(M,R) is given to show that the above-mentioned shortcoming of EQLM can be resolved to some extent.
引文
蒋通,邢海灵.2007.水平土层地震反应分析考虑频率相关性的等效线性化方法[J].岩土工程学报,29(2):218--224.
李小军,彭青.2001.不同类别场地地震动参数的计算分析[J].地震工程与工程振动,21(1):29--36.
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刘峥,沈建文,石树中,余湛.2009.软土对峰值加速度的放大作用[J].同济大学学报(自然科学版),37(5):607--611.
刘峥.2009.用震级和距离参数修正等效线性化波动方法的研究[D].上海:同济大学博士论文:74--77.
齐文浩,薄景山.2007.土层地震反应等效线性化方法综述[J].世界地震工程,23(4):211--226.
沈建文,蔡长青,邱瑛.1997.XQH1.00地震安全性评价工作程序包简介[J].地震学刊,(1):46--51.
郉海灵.2007.考虑场地特征和空间相关性的地震动模拟方法研究[D].上海:同济大学博士论文:26--29.
Bardet J P,Ichii K,Lin C H.2000.AComputer Programfor Equivalent-Linear Earthquake Site Response Analyses ofLayered Soil Deposits[R].Berkeley:University of Southern California:37.
Furumoto Y,Sugito M,Yashi ma A.2002.Frequency-dependent equivalent linearizedtechnique for FEMresponse analy-sis of ground[C]∥The Proceedings ofthe Twelfth World Conference on Earthquake Engineering.Auckland.NewZealand:New Zealand Society for Earthquake Engineering.Paper,No.1808:1--8.
Hartzell S,Bonilla L F,Williams R A.2004.Prediction of nonlinear soil effects[J].Bull SeismSoc Amer,94(5):1609--1629.
Yoshida N,Kobayashi S,Suetomi I,Miura K.2002.Equivalent linear method considering frequency dependent charac-teristics of stiffness and damping[J].Soil Dyn Earthq Eng,22(3):205--222.
李小军,彭青.2001.不同类别场地地震动参数的计算分析[J].地震工程与工程振动,21(1):29--36.
廖振鹏,李小军.1989.地表土层地震反应的等效线性化解法[M]∥廖振鹏主编.地震小区划.北京:地震出版社:141--153.
刘峥,沈建文,石树中,余湛.2009.软土对峰值加速度的放大作用[J].同济大学学报(自然科学版),37(5):607--611.
刘峥.2009.用震级和距离参数修正等效线性化波动方法的研究[D].上海:同济大学博士论文:74--77.
齐文浩,薄景山.2007.土层地震反应等效线性化方法综述[J].世界地震工程,23(4):211--226.
沈建文,蔡长青,邱瑛.1997.XQH1.00地震安全性评价工作程序包简介[J].地震学刊,(1):46--51.
郉海灵.2007.考虑场地特征和空间相关性的地震动模拟方法研究[D].上海:同济大学博士论文:26--29.
Bardet J P,Ichii K,Lin C H.2000.AComputer Programfor Equivalent-Linear Earthquake Site Response Analyses ofLayered Soil Deposits[R].Berkeley:University of Southern California:37.
Furumoto Y,Sugito M,Yashi ma A.2002.Frequency-dependent equivalent linearizedtechnique for FEMresponse analy-sis of ground[C]∥The Proceedings ofthe Twelfth World Conference on Earthquake Engineering.Auckland.NewZealand:New Zealand Society for Earthquake Engineering.Paper,No.1808:1--8.
Hartzell S,Bonilla L F,Williams R A.2004.Prediction of nonlinear soil effects[J].Bull SeismSoc Amer,94(5):1609--1629.
Yoshida N,Kobayashi S,Suetomi I,Miura K.2002.Equivalent linear method considering frequency dependent charac-teristics of stiffness and damping[J].Soil Dyn Earthq Eng,22(3):205--222.
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