关于抗震设计场地反应分析客观性的一些探讨
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摘要
在工程抗震设计领域,以SHAKE为工具的场地反应分析已得到广泛应用。场地反应分析简单、易行,然而要得到准确、可靠的分析成果仍需要长期的经验积累和相当的技巧。其中需特别注意的是:场地反应分析所需要的各土层参数均具有相当大的不确定性。这些不确定因素主要来自于:初始剪切模量G0(或最大剪切模量Gmax)、剪切模量衰减曲线、阻尼曲线以及可能存在的软弱土层。对于大型基建工程,场地反应分析的成果对于整个工程的安全、经济性都有重大影响;因此,针对其不确定性应该进行严谨地论证,并在工程设计中充分考虑。建议对各主要参数进行敏感度分析,并将结果综合起来以形成一套理性、可靠的场地反应分析方法。
SHAKE has been widely used by engineers to predict ground responses in seismic design.Although SHAKE analysis is simple and straightforward,to generate accurate and reliable output still requires significant experience and skills;especially with regard to the significant uncertainty of soil parameters in ground response analysis.These uncertainties come from a number of factors such as initial shear modulus(or maximum shear modulus),dynamic shear modulus degradation curves,damping curves,and the existence of soft layers.For large infrastructure analysis,the results of ground response analysis have an important influence on the economy and safety of the whole design.Therefore we propose to perform a systematic sensitivity analysis to account for the uncertainties.Based on the results from these analyses,a systematical and rational way for researchers and industrial designers to carry out reliable ground response analyses is suggested.
SHAKE has been widely used by engineers to predict ground responses in seismic design.Although SHAKE analysis is simple and straightforward,to generate accurate and reliable output still requires significant experience and skills;especially with regard to the significant uncertainty of soil parameters in ground response analysis.These uncertainties come from a number of factors such as initial shear modulus(or maximum shear modulus),dynamic shear modulus degradation curves,damping curves,and the existence of soft layers.For large infrastructure analysis,the results of ground response analysis have an important influence on the economy and safety of the whole design.Therefore we propose to perform a systematic sensitivity analysis to account for the uncertainties.Based on the results from these analyses,a systematical and rational way for researchers and industrial designers to carry out reliable ground response analyses is suggested.
引文
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[4]YOUD T L,IDRISS I M,ANDRUS R D,et al.Liquefaction resistance of soils:Summary report from the1996 NCEER and 1998 NCEER/NSF workshops onevaluation of liquefaction resistance of soils[J].Journalof Geotechnical and Geoenvironmental Engineering,2001,127(10):817-833.
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[6]LI C,BORJA R I,REGUEIRO R A.Dynamics of porousmedia at finite strain[J].Computer Methods in AppliedMechanics and Engineering,2004,193(36-38):3837-3870.
[2]Electric Power Research Institute.TR-102293 Guidelinesfor determining design basis ground motions[S].USA:Electric Power Research Institute,1993.
[3]日本道路协会.公路桥梁设计规范第5部分:地震设计[S].日本:日本道路协会,2002.
[4]YOUD T L,IDRISS I M,ANDRUS R D,et al.Liquefaction resistance of soils:Summary report from the1996 NCEER and 1998 NCEER/NSF workshops onevaluation of liquefaction resistance of soils[J].Journalof Geotechnical and Geoenvironmental Engineering,2001,127(10):817-833.
[5]BORJA R I,AMIES A P.Multiaxial cyclic plasticitymodel for clays[J].Journal of GeotechnicalEngineering,ASCE,1994,120(6):1051-1070.
[6]LI C,BORJA R I,REGUEIRO R A.Dynamics of porousmedia at finite strain[J].Computer Methods in AppliedMechanics and Engineering,2004,193(36-38):3837-3870.
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