基于虚拟激励法的沉积盆地场地地震反应分析
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摘要
基于四川盆地及台北盆地震害分布的差异,将虚拟激励法与有限单元法结合,应用于场地的随机地震反应分析中。将沉积盆地截面简化成等腰梯形,建立二维平面应变模型,通过数值试验,研究了沉积盆地场地的地震反应,探讨了盆地效应的影响参数。主要结论如下:①由于地震波在盆地边缘的反射效应,盆地场地表面的地震反应较成层场地有较大的改变,水平加速度标准差可提高150%;场地边缘附近的竖直加速度标准差与水平加速度标准差量级相当;②当盆地宽度较大时,盆地边缘仅对场地边缘附近的地震反应有较大影响,影响范围大概为1倍(以水平加速度标准差为评价标准)或者3倍(以竖直加速度标准差为评价标准)盆地边缘倾斜基岩面的水平投影长度;③随着盆地深度的增加,盆地场地表面的最大水平及竖直加速度标准差增加;④随着土层剪切波速的增加,盆地场地表面的最大水平加速度标准差几乎不变,但最大竖直加速度标准差减小。
The spatial distributions of disasters in Taipei Basin and Sichuan Basin are different.A series of two-dimensional plane strain models for sedimentary basins,the cross sections of which are simplified to isosceles trapezium,are established to analyze the seismic response of sedimentary basins and to study the major influencing parameters of basin effect.It is concluded that because of the reflection of seismic waves at the boundary of basins,contrasted to horizontal layered sites,the seismic response of basin sites makes a large difference.The standard deviation of horizontal acceleration may rise by 150%,and the standard deviation of vertical acceleration is corresponding to that of horizontal acceleration in magnitude.If the size of basins is relatively large,the basin effect just has a relatively distinct impact on the seismic response of the edge of basins,and the incidence is approximately equal to the projected length of the inclined bedrock surface at the edge of basins,concluded by the standard deviation of horizontal acceleration,or triple of that,concluded by the standard deviation of vertical acceleration.The maximum standard deviation of acceleration increases with the increase of the depth of basin sites.The maximum standard deviation of horizontal acceleration remains virtually unchanged and that of vertical acceleration reduces with the increase of shear wave velocity of soil.
The spatial distributions of disasters in Taipei Basin and Sichuan Basin are different.A series of two-dimensional plane strain models for sedimentary basins,the cross sections of which are simplified to isosceles trapezium,are established to analyze the seismic response of sedimentary basins and to study the major influencing parameters of basin effect.It is concluded that because of the reflection of seismic waves at the boundary of basins,contrasted to horizontal layered sites,the seismic response of basin sites makes a large difference.The standard deviation of horizontal acceleration may rise by 150%,and the standard deviation of vertical acceleration is corresponding to that of horizontal acceleration in magnitude.If the size of basins is relatively large,the basin effect just has a relatively distinct impact on the seismic response of the edge of basins,and the incidence is approximately equal to the projected length of the inclined bedrock surface at the edge of basins,concluded by the standard deviation of horizontal acceleration,or triple of that,concluded by the standard deviation of vertical acceleration.The maximum standard deviation of acceleration increases with the increase of the depth of basin sites.The maximum standard deviation of horizontal acceleration remains virtually unchanged and that of vertical acceleration reduces with the increase of shear wave velocity of soil.
引文
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[18]胡聿贤.弹性体系在平稳和平稳化地面运动下的反应[R].北京:中国科学院工程力学研究所,1962.(HU Yu-xian.Response of elastic system under stationary groundmotion[R].Beijing:Institute of Engineering Mechanics,Academia Sinica,1962.(in Chinese))
[19]王光远.在非平稳强地震作用下结构反应的分析方法[J].土木工程学报,1964(1):14–22.(WANG Guang-yuan.Analysis method of structural response under non-stationarystrong ground motion[J].China Civil Engineering Journal,1964(1):14–22.(in Chinese))
[20]曾心传,秦小军.土层对地震的随机反应分析[J].地震工程与工程振动,1998(3):27–39.(ZENG Xin-chuan,QINXiao-jun.Analysis of random response of soil layer toearthquake[J].Journal of Earthquake Engineering andEngineering Vibration,1998(3):27–39.(in Chinese))
[21]林家浩.随机地震响应的确定性算法[J].地震工程与工程振动,1985(1):89–94.(LIN Jia-hao.A deterministic methodfor the computation of stochastic earthquake responsE[J].Journal of Earthquake Engineering and EngineeringVibration,1985(1):89–94.(in Chinese))
[2]彭承光,李运贵.场地地震效应工程勘察基础[M].北京:地震出版社,2004.(PENG Cheng-guang,LI Yun-gui.Baseof investigation of site effect in earthquake[M].Beijing:Seismological Press,2004.(in Chinese))
[3]袁丽侠.场地土对地震波的放大效应[J].世界地震工程,2003(1):113–120.(YUAN Li-xia.The amplifying effect ofground soil to earthquake wave[J].World EarthquakeEngineering,2003(1):113–120.(in Chinese))
[4]RODONIKOVA B,LARKOVA T,SHLEIFER V.Genesis,dynamic process,classification and evolution of sedimentarybasins[C]//30th International Geological Congress,Beijing,1996.
[5]TRIFUNAC M D.Surface motion of a semi-cylindricalalluvial valley for incident plane SH waves[J].Bulletin of theSeismological Society of America,1971,61(6):1755–1770.
[6]WONG H L,TRIFUNAC M D.Surface motion of asemi-elliptical alluvial valley for incident phase SH waves[J].Bulletin of the Seismological Society of America,1974,64(5):1389–1408.
[7]LEE V W.Three-dimensional diffraction of plane P,SV andSH waves by a hemispherical alluvial valley[J].Soil Dynamicsand Earthquake Engineering,1984,3(3):133–144.
[8]杨彩红,梁建文,张郁山.含多个圆弧状沉积层河谷场地对平面SH波散射问题的解析解[J].地震工程与工程振动,2010(3):22–30.(YANG Cai-hong,LIANG Jian-wen,ZHANG Yu-shan.Analytical solution to the scatteringproblem of valley site containing multiple circular-arcalluvial layers in the case of plane SH waves incidence[J].Journal of Earthquake Engineering and EngineeringVibration,2010(3):22–30.(in Chinese))
[9]李伟华,赵成刚.含软夹层的层状沉积河谷场地的地震动力响应分析[J].岩土力学,2009,30(1):45–51,58.(LI Wei-hua,ZHAO Cheng-gang.Analysis of seismic dynamic response oflayered alluvial valleys with soft interlayer[J].Rock and SoilMechanics,2009,30(1):45–51,58.(in Chinese))
[10]赵志新,赵昭,徐纪人,等.用数值模拟格林函数方法合成近源地面运动地震图[J].科学通报,2006(18):2181–2188.(ZHAO Zhi-xin,ZHAO Zhao,XU Ji-ren,et al.Synthetic seismograms of near source ground motion bynumerical simulation of green's function[J].Chinese ScienceBulletin,2006(18):2181–2188.(in Chinese))
[11]MA S,ARCHULETA R J,PAGE M T.Effects of large-scalesurface topography on ground motions,as demonstrated by astudy of the San Gabriel Mountains,Los Angeles,California[J].Bulletin of the Seismological Society ofAmerica,2007,97(6):2066–2079.
[12]SHYU W,TENG T.SH wave scattering at a trapezoid hilland a semi-cylindrical alluvial basin by hybrid method[C]//International Conference on Consumer Electronics,Communications and Networks,CECNet 2011,2011.
[13]郭恩,周锡元.汶川地震盆地效应的思考与建议[J].防灾减灾工程学报,2010(4):459–465.(GUO En,ZHOUXi-yuan.Study on basin effects of wenchuan earthquake[J].Journal of Disaster Prevention and Mitigation Engineering,2010(4):459–465.(in Chinese))
[14]HOUSNER G W.Characteristics of strong motionearthquake[J].Bulletin of the Seismological Society ofAmerica,1947,37:19–31.
[15]BARSTEIN M F.Application of probability methods fordesign the effect of seismic forces on engineeringstructures[C]//The 2nd World Conference on EarthquakeEngineering,Tokyo,Japan.1960.
[16]ROSENBLUETH E.Probabilistic design to resist earthquake[J].Proceedings of ASCE,1964,90(EM5):189–219.
[17]KANAI K.Semi-empirical formula for the seismiccharacteristics of ground[J].Bulletin of the EarthquakeResearch Institute,1957,35:306–325.
[18]胡聿贤.弹性体系在平稳和平稳化地面运动下的反应[R].北京:中国科学院工程力学研究所,1962.(HU Yu-xian.Response of elastic system under stationary groundmotion[R].Beijing:Institute of Engineering Mechanics,Academia Sinica,1962.(in Chinese))
[19]王光远.在非平稳强地震作用下结构反应的分析方法[J].土木工程学报,1964(1):14–22.(WANG Guang-yuan.Analysis method of structural response under non-stationarystrong ground motion[J].China Civil Engineering Journal,1964(1):14–22.(in Chinese))
[20]曾心传,秦小军.土层对地震的随机反应分析[J].地震工程与工程振动,1998(3):27–39.(ZENG Xin-chuan,QINXiao-jun.Analysis of random response of soil layer toearthquake[J].Journal of Earthquake Engineering andEngineering Vibration,1998(3):27–39.(in Chinese))
[21]林家浩.随机地震响应的确定性算法[J].地震工程与工程振动,1985(1):89–94.(LIN Jia-hao.A deterministic methodfor the computation of stochastic earthquake responsE[J].Journal of Earthquake Engineering and EngineeringVibration,1985(1):89–94.(in Chinese))
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