远场大地震作用下深软场地设计地震动参数研究
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摘要
针对苏州城区典型地层剖面,建立大尺度深软场地的二维精细化非线性有限元分析模型,研究了大地震远场地震动作用于深软场地的设计地震动参数。结果表明:①大地震远场地震动作用时的深软场地地表地震动峰值加速度(PGA)明显大于人工波作用时的地表PGA,输入地震动特性、土介质的横向不均匀性及其非线性,使不同地表位置的PGA存在明显的变异性;②深软场地的地表设计地震动参数max,max和g T值远远大于现行国家规范或标准的取值,且max随地震动水平的提高而增大;③沿土层深度的PGA折减系数,对深度5 m以浅土层可取1,对深度35 m以深土层可取0.65,对中间深度土层可线性内插;④苏州深软场地土的最大剪应变幅值出现在土层深度10 m附近的窄带区域内,且中震、大震水平时,深度10～20 m的土介质处于弹塑性变形到大变形的过渡阶段,对该深度的地下结构,尤其是细长地下结构的抗震不利。对于类似苏州城区的深软场地,应充分考虑远场大地震效应的影响。
Based on the typical stratigraphic section in the downtown area of Suzhou City,large-scale refined two-dimensional(2D) finite element(FE) nonlinear analytical models for deep soft site are established.Ground motion design parameters of the deep soft site under far-field large earthquake are investigated.The results indicate that:(1) The peak ground acceleration(PGA) under far-field large earthquake is significantly larger than that under artificial wave.The characteristics of input ground motion as well as inhomogeneity and nonlinearity of ground soils which make PGA at different ground positions have obvious variability.(2) The seismic design parameters,αmax,βmax and Tg T,of the deep soft site are far greater than those according to the existing national code.Moreover,the value of βmax increases as the ground motion level grows.(3) The PGA reduction factor with depth can be obtained as follows: to the soils with depth smaller than 5 m,it is 1.0,while to the soils 35 m in depth,it is 0.65,and it can be obtained by means of the linear interpolation when the soils are between 5 m and 35 m in depth.(4) The maximum shear strain appears at a narrow-band area around 10 m in depth.Under large and medium earthquakes,the soils between 10 and 20 m in depth behave from elasticoplastic deformation to large one,which may bring adverse influence on the underground structures within this band,especially on the slim-lined underground structures.
Based on the typical stratigraphic section in the downtown area of Suzhou City,large-scale refined two-dimensional(2D) finite element(FE) nonlinear analytical models for deep soft site are established.Ground motion design parameters of the deep soft site under far-field large earthquake are investigated.The results indicate that:(1) The peak ground acceleration(PGA) under far-field large earthquake is significantly larger than that under artificial wave.The characteristics of input ground motion as well as inhomogeneity and nonlinearity of ground soils which make PGA at different ground positions have obvious variability.(2) The seismic design parameters,αmax,βmax and Tg T,of the deep soft site are far greater than those according to the existing national code.Moreover,the value of βmax increases as the ground motion level grows.(3) The PGA reduction factor with depth can be obtained as follows: to the soils with depth smaller than 5 m,it is 1.0,while to the soils 35 m in depth,it is 0.65,and it can be obtained by means of the linear interpolation when the soils are between 5 m and 35 m in depth.(4) The maximum shear strain appears at a narrow-band area around 10 m in depth.Under large and medium earthquakes,the soils between 10 and 20 m in depth behave from elasticoplastic deformation to large one,which may bring adverse influence on the underground structures within this band,especially on the slim-lined underground structures.
引文
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[6]郭晓云,薄景山,张宇东,等.抗震设计反应谱的标定方法[J].世界地震工程,2011,27(1):66–71.(GUO Xiao-yun,BO Jing-shan,ZHANG Yu-dong,et al.Methods of calibrating seismic design response spectrum[J].World Earthquake Engineering,2011,27(1):66–71.(in Chinese))
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[9]门进杰,史庆轩,陈曦虎.汶川地震对远震区高层建筑造成的震害及设计建议[J].西安建筑科技大学学报(自然科学版),2008,40(5):648–653.(MEN Jin-jie,SHI Qing-xuan,CHEN Xi-hu.Seismic damage of high buildings caused in the ramote areas from epicenter and aseismic design suggestion[J].Journal of Xi'an University of Architecture and Technology(Natural Science Edition),2008,40(5):648–653.(in Chinese))
[10]李善邦.中国地震[M].北京:地震出版社,1981.(LI Shan-bang.Earthquake research in China[M].Beijing:Earthquake Press,1981.(in Chinese))
[11]彭艳菊,孟小红,吕悦军,等.我国近海地震活动特征及其与地球物理场的关系[J].地球物理学进展,2008,23(5):1377–1388.(PENG Yan-ju,MENG Xiao-hong,LüYue-jun,et al.The seismicity of China offshore seas and its relationship with geophysical fields[J].Progress in Geophysics,2008,23(5):1377–1388.(in Chinese))
[12]战吉艳,陈国兴,胡庆兴.苏州第四纪沉积土动剪切模量比和阻尼比试验研究[J].岩土工程学报,2012,34(3):559–566.(ZHAN Ji-yan,CHEN Guo-xing,HU Qing-xing.Experimental study on dynamic shear modulus ratio and damping ratio of Suzhou quaternary sedimentary soil[J].Chinese Journal of Geotechnical Engineering,2012,34(3):559–566.(in Chinese))
[13]刘晶波,谷音,杜义欣.一致黏弹性人工边界及黏弹性边界单元[J].岩土工程学报,2006,28(9):1070–1075.(LIU Jing-bo,GU Yin,DU Yi-xin.Consistent viscous-spring artificial boundaries and viscous-spring boundary elements[J].Chinese Journal of Geothchnical Engineering,2006,28(9):1070–1075.(in Chinese))
[14]陈国兴,陈磊,景立平,等.地铁地下结构抗震分析并行计算显式与隐式算法比较[J].铁道学报,2011,33(11):111–118.(CHEN Guo-xing,CHEN Lei,JING Li-ping,et al.Comparison of implicit and explicit finite element methods with parallel computing for seismic response analysis of metro underground structures[J].Journal of the China Railway Society,2011,33(11):111–118.(in Chinese))
[15]战吉艳,陈国兴,刘建达.苏州城区场地等效剪切波速计算深度取值探讨[J].地震工程与工程振动,2012,32(5):1–6.(ZHAN Ji-yan,CHEN Guo-xing,LIU Jian-da.Discussion on calculation depth selection of equivalent shear wave velocity for site classification in urban area of Suzhou[J].Journal of Earthquake Engineering and Engineering Vibration,2012,32(5):1–6.(in Chinese))
[16]吴健,高孟潭.场地相关设计反应谱特征周期的统计分析[J].中国地震,2004,20(3):263–268.(WU Jian,GAO Meng-tan.Statistical analysis on corner period of site-related design spectrum[J].Earthquake Research in China,2004,20(3):263–268.(in Chinese))
[17]ZHAN J Y,CHEN G X,JIN D D.Seismic response characteristics of deep soft site with depth under far-field ground motion of great earthquake[J].Applied Materials and Electronics Engineering,2012:378–379,477–483.
[2]吕悦军,彭艳菊,兰景岩,等.场地条件对地震动参数影响的关键问题[J].震灾防御技术,2008,3(2):126–135.(LüYue-jun,PENG Yan-ju,LAN Jing-yan,et al.Some key problems about site effects on seismic ground motion parameters[J].Technology for Earthquake Disaster Prevention,2008,3(2):126–135.(in Chinese))
[3]吕红山,赵凤新.适用于中国场地分类的地震动反应谱放大系数[J].地震学报,2007,29(1):67–76.(LüHong-shan,ZHAO Feng-xin.Site coefficients suitable to China site category[J].Acta Seismic Gica Sinica,2007,29(1):67–76.(in Chinese))
[4]张力方,吕悦军,兰景岩.天津软土场地对地震动参数的影响[M].北京:地震出版社,2008:108–116.(ZHANG Li-fang,LüYue-jun,LAN Jing-yan.Effects of soft soil condition in Tianjin on ground motion parameters[M].Beijing:Earthquake Press,2008.(in Chinese))
[5]吕悦军,唐荣余,彭艳菊.烟台海岸软土场地特征及对地震动参数的影响[J].中国地震,2004,20(4):323–329.(LüYue-jun,TANG Rong-yu,PENG Yan-ju.Study on site classification and seismic paramerters for the Yantai seashore[J].Earthquake Research in China,2004,20(4):323–329.(in Chinese))
[6]郭晓云,薄景山,张宇东,等.抗震设计反应谱的标定方法[J].世界地震工程,2011,27(1):66–71.(GUO Xiao-yun,BO Jing-shan,ZHANG Yu-dong,et al.Methods of calibrating seismic design response spectrum[J].World Earthquake Engineering,2011,27(1):66–71.(in Chinese))
[7]SEED H B,ROMO M P,SUNJ I,et al.The Mexico earthquake of September 19,1985:relationships between soil conditions and earthquake ground motions[J].Earthquake Spectra,1988,4(4):687–729.
[8]DOBRY R,BORCHERDT R,CROUSE C,et al.New site coefficients and site classification system used in recent building seismic code provisions[J].Earthquake Spectra.2000,16(1):41–67.
[9]门进杰,史庆轩,陈曦虎.汶川地震对远震区高层建筑造成的震害及设计建议[J].西安建筑科技大学学报(自然科学版),2008,40(5):648–653.(MEN Jin-jie,SHI Qing-xuan,CHEN Xi-hu.Seismic damage of high buildings caused in the ramote areas from epicenter and aseismic design suggestion[J].Journal of Xi'an University of Architecture and Technology(Natural Science Edition),2008,40(5):648–653.(in Chinese))
[10]李善邦.中国地震[M].北京:地震出版社,1981.(LI Shan-bang.Earthquake research in China[M].Beijing:Earthquake Press,1981.(in Chinese))
[11]彭艳菊,孟小红,吕悦军,等.我国近海地震活动特征及其与地球物理场的关系[J].地球物理学进展,2008,23(5):1377–1388.(PENG Yan-ju,MENG Xiao-hong,LüYue-jun,et al.The seismicity of China offshore seas and its relationship with geophysical fields[J].Progress in Geophysics,2008,23(5):1377–1388.(in Chinese))
[12]战吉艳,陈国兴,胡庆兴.苏州第四纪沉积土动剪切模量比和阻尼比试验研究[J].岩土工程学报,2012,34(3):559–566.(ZHAN Ji-yan,CHEN Guo-xing,HU Qing-xing.Experimental study on dynamic shear modulus ratio and damping ratio of Suzhou quaternary sedimentary soil[J].Chinese Journal of Geotechnical Engineering,2012,34(3):559–566.(in Chinese))
[13]刘晶波,谷音,杜义欣.一致黏弹性人工边界及黏弹性边界单元[J].岩土工程学报,2006,28(9):1070–1075.(LIU Jing-bo,GU Yin,DU Yi-xin.Consistent viscous-spring artificial boundaries and viscous-spring boundary elements[J].Chinese Journal of Geothchnical Engineering,2006,28(9):1070–1075.(in Chinese))
[14]陈国兴,陈磊,景立平,等.地铁地下结构抗震分析并行计算显式与隐式算法比较[J].铁道学报,2011,33(11):111–118.(CHEN Guo-xing,CHEN Lei,JING Li-ping,et al.Comparison of implicit and explicit finite element methods with parallel computing for seismic response analysis of metro underground structures[J].Journal of the China Railway Society,2011,33(11):111–118.(in Chinese))
[15]战吉艳,陈国兴,刘建达.苏州城区场地等效剪切波速计算深度取值探讨[J].地震工程与工程振动,2012,32(5):1–6.(ZHAN Ji-yan,CHEN Guo-xing,LIU Jian-da.Discussion on calculation depth selection of equivalent shear wave velocity for site classification in urban area of Suzhou[J].Journal of Earthquake Engineering and Engineering Vibration,2012,32(5):1–6.(in Chinese))
[16]吴健,高孟潭.场地相关设计反应谱特征周期的统计分析[J].中国地震,2004,20(3):263–268.(WU Jian,GAO Meng-tan.Statistical analysis on corner period of site-related design spectrum[J].Earthquake Research in China,2004,20(3):263–268.(in Chinese))
[17]ZHAN J Y,CHEN G X,JIN D D.Seismic response characteristics of deep soft site with depth under far-field ground motion of great earthquake[J].Applied Materials and Electronics Engineering,2012:378–379,477–483.
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