渭河盆地中土层场地对地震动的放大作用
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摘要
土层场地对地震动的影响较大,建(构)筑物的选址及其抗震设防必须考虑土层场地的放大作用,以避免或减轻其震害.汶川地震中,布设在渭河盆地中的数字强震动台网共有27个台站(包括2个基岩台站和25个土层台站)获得良好的主震加速度时程.利用这些加速度时程,选择汤峪台做为参考场地,基于考虑几何衰减的传统谱比法分析研究了25个土层场地的放大作用.结果表明:(1)汶川地震中渭河盆地土层场地上的加速度峰值(PGA)有随震中距增加而减小的趋势,且与土层的厚度无关.(2)根据汶川地震中渭河盆地土层场地的加速度反应谱特征及其对地震动的放大作用特征,渭河盆地的土层场地可分为3类:深厚、中厚和薄土层场地.而且,深厚、中厚和薄土层场地分别对地震动的低频、1 Hz附近和高频分量放大作用显著;值得注意的是,深厚土层对地震动的高频分量也有一定程度的放大,只不过相对于低频分量的放大作用较小.(3)汶川地震中渭河盆地的土层场地对不同方向地震动的放大作用不同,且有EW>NS>UD的关系.(4)汶川地震中从宝鸡到眉县沿着盆地边缘分布的Ⅶ度烈度异常区是盆地边缘效应和土层场地对地震动放大作用共同作用的结果.
Effects of soil sites on ground motion are relatively serious,their amplification effects on ground motion must be considered in site selection and seismic fortification of buildings to prevent or mitigate seismic hazard of buildings.The mainshock's acceleration time histories of 27 stations(including 2 bedrock stations and 25 soil stations)in the digital strong motion seismograph network installed in the Weihe basin in Wenchuan great earthquake were recorded. Utilizing the acceleration time histories,the amplification effects of 25 soil stations are studied and analyzed by traditional spectral ratio method with geometric attenuation while Tangyu station is seclected as reference site.The results are as follows.(1)Peak ground accelerations(PGAs) on the soil sites in the Weihe basin in the Wenchuan great earthquake have decreasing trends with the epicentral distances regardless of the soil thickness.(2)According to the characteristics of both acceleration response spectra of soil sites and amplification effects of soil sites on ground motions in the Weihe basin in the Wenchuan great earthquake,the soil sites in Weihe basin can be classified into 3 categories,i.e.,deep,intermediate,and shollow soil sites,which respectively amplifies the low frequency components,components in the vicinity of 1 Hz,and high frequency components of ground motions significantly.It is noteworthy that high frequency components of ground motions are also amplified to a centain extent for deep soil sites,but the amplification factors of high frequency components are smaller than those of low frequency components.(3) The amplification effects of soil sites on different direction(i.e.EW,NS and UD)ground motions in the Weihe basin in the Wenchuan great earthquake are different.Generally,EW>NS> UD.(4)Abnormal area of intensity Ⅶ along basin edge from Baoji to Meixian in the Weihe basin in the Wenchuan great earthquake resulted from combined amplification effects of both soil sites and basin edge effects on ground motions.
Effects of soil sites on ground motion are relatively serious,their amplification effects on ground motion must be considered in site selection and seismic fortification of buildings to prevent or mitigate seismic hazard of buildings.The mainshock's acceleration time histories of 27 stations(including 2 bedrock stations and 25 soil stations)in the digital strong motion seismograph network installed in the Weihe basin in Wenchuan great earthquake were recorded. Utilizing the acceleration time histories,the amplification effects of 25 soil stations are studied and analyzed by traditional spectral ratio method with geometric attenuation while Tangyu station is seclected as reference site.The results are as follows.(1)Peak ground accelerations(PGAs) on the soil sites in the Weihe basin in the Wenchuan great earthquake have decreasing trends with the epicentral distances regardless of the soil thickness.(2)According to the characteristics of both acceleration response spectra of soil sites and amplification effects of soil sites on ground motions in the Weihe basin in the Wenchuan great earthquake,the soil sites in Weihe basin can be classified into 3 categories,i.e.,deep,intermediate,and shollow soil sites,which respectively amplifies the low frequency components,components in the vicinity of 1 Hz,and high frequency components of ground motions significantly.It is noteworthy that high frequency components of ground motions are also amplified to a centain extent for deep soil sites,but the amplification factors of high frequency components are smaller than those of low frequency components.(3) The amplification effects of soil sites on different direction(i.e.EW,NS and UD)ground motions in the Weihe basin in the Wenchuan great earthquake are different.Generally,EW>NS> UD.(4)Abnormal area of intensity Ⅶ along basin edge from Baoji to Meixian in the Weihe basin in the Wenchuan great earthquake resulted from combined amplification effects of both soil sites and basin edge effects on ground motions.
引文
[1] 周锡元,王广军,苏经宇.场地·地基·设计地震.北京:地 震出版社,1991 Zhou X Y,Wang G J,Su J Y.Site,Foundation,Design Earthquake (in Chinese).Beijing:Seismological Press,1991
[2] 孙小鹏,冯伯林,张战怀.深软土场地上高层住宅的地震安全 性问题.地震学刊,1999,3:1～5 Sun X P,Feng B L,Zhang Z H.Seismic safe problem of high building on deep soft site.Journal of Seismology (in Chinese),1999,3:1～5
[3] Bala A,Grecu B,Ciugudean V,Raileanu V.Dynamic properties of the Quaternary sedimentary rocks and their influence on seismic site effect:case study in Bucharest city, Romania.Soil Dynamic and Earthquake Engineering ,2009 ,29(1) :144～154
[4] 袁丽霞.场地土对地震波的放大作用.世界地震工程,2003,19(1) :113～120 Yuan L X.The amplifying effect of ground soil to earthquake wave.World Earthquake Engineering (in Chinese),2003,19(1) :113～120
[5] Borcherdt R D.Effects of local geology on ground motion near San Francisco Bay.Bull.Seism.Soc.Am.,1970,60(1) :29～61
[6] Andrews D J.Objective determination of source parameters and similarity of earthquakes of different size.In:Das S,Boatwright J,Scholz C H eds.Earthquake Source Mechanics.American Geophysical Union,Washington D.C.,1986,259～268
[7] Field E H,Jacob K H.A comparison and test of various site-response estimation techniques,including three that are not reference-site dependent.Bull.Seism.Soc.Am.1995,85(4) :1127～1143
[8] 章文波,谢礼立,郭明珠.利用强震记录分析场地的地震反应.地震学报,2001,23(6) :604～614 Zhang W B,Xie L L,Guo M Z.Estimation on site amplification from different methods using strong motion data obtained in Tangshan,China.Acta Seismologica Sinica (in Chinese),2001,23(6) :604～614
[9] Lermo J,Chrivez-Garcia F J.Site effect evaluation using spectral ratios with only one station.Bull.Seism.Soc.Am.,1993,83(5) :1574～1594
[10] Bonilla L F,Steidl J H,Lindley G T,et al.Site amplification in the San Fernando valley,California:variability of site-effect estimation using the S-Wave,Coda,and H/V Methods.Bull.Seism.Soc.Am.,1997,87(3) :710～730
[11] Atkinson G M,Cassidy J F.Integrated use of seismograph and strong-motion data to determine soil amplification:response of the Fraser River Delta to the Duvall and Georgia Strait earthquake.Bull.Seism.Soc.Am.,2000,90 (4) :1028～1040
[12] Malagnini L,Mayeda K,Akinci A,et al.Estimating absolute site effects.Bull.Seism.Soc.Am.,2004,94(4) :576～590
[13] Sokolov V,Loh C H,Wen K L.Evaluation of generalized site response function for typical soil classes (B,C,and D) in Taiwan.Earthquake Spectra ,2004,20:1279～1316
[14] 李永善.西安地裂及渭河盆地活断层研究.北京:地震出版社,1992 Li Y S.Research on ground fissures in Xi an Region and active faults in Weihe Basin (in Chinese).Beijing:Seismological Press,1992
[15] 刘护军.渭河盆地的形成演化与东秦岭的隆升[博士论文].西安:西北大学,2004 Liu H J.Formation and evolution of the Weihe river basin and uplift of the eastern Qinling mountains [Ph.D.thesis](in Chinese).Xi'an:Northwest University,2004
[16] 胡孟春.渭河盆地的地质构造与构造地貌类型.地理研究,1989,8(4) :56～64 Hu M C.The relationship between the tectonic landforms and structure in the Weihe river basin.Geographic Research (in Chinese),1989,1989 ,8(4) :56～64
[17] 张宗祜.九曲黄河万里沙-黄河与黄土高原.北京:清华大学出版社,2000 Zhang Z H.Sands in ten thousand miles of Yellow river turning many times-Yellow River and Loess Plateau (in Chinese).Beijing:Tsinghua University Press,2000
[18] 王景明.渭河地堑断裂构造研究.地质论评,1984,30(3) :217～223 Wang J M.A study on the tectonics of the Weihe river graben.Geological Review (in Chinese) ,1984,30(3) :217～223
[19] 权新昌.渭河盒地断裂构造研究.中国煤田地质,2005,17(3) :1～4 Quan X C.Study on faulted structure of Weihe basin.Coal Geology of China (in Chinese),2005 ,17(3) :1～4
[20] 彭建兵.渭河断裂带的构造演化与地震活动.地震地质,1992,14(2) :113～120 Peng J B.Tectonic evolution and seismicity of Weihe fault zone.Seismology and Geology (in Chinese),1992,14(2) :113～120
[21] 韩恒悦,张逸,袁志祥.渭河断陷盆地带的形成演化及断块运动.地震研究,2002,25(4) :362～368 Han H Y,Zhang Y,Yuan Z X.The evolution of Weihe down-faulted basin and the movement of the fault blocks.Journal of Seismological Research (in Chinese) ,2002,25(4) :362～368
[22] 中国地震局震害防御司.汶川8． 0级地震未校正加速度记录.中国强震记录汇报.北京:地震出版社,2008,12(1) :1～302 Burean of Earthquake Damage Protection,CEA.Uncorrected acceleration records of Wenchuan earthquake (M_s8． 0) (in Chinese).Report on strong earthquake motion records in China.Beijing:Seismological Press,2008,12(1) :1～302
[23] Bard P Y.Effects of surface geology on ground motion:recent results and remaining issues.In:Duma,Editor.Proceedings of 10~(th) European Conference on Earthquake Engineering,Vienna,Austria,1995,305～323
[24] 袁一凡.四川汶川8． 0级地震损失评估.地震工程与工程振动.2008,28(5) :10～19 Yuan Y F.Loss assessment of Wenchuan earthquake.Journal of Earthquake Engineering and Engineering Vibration (in Chinese) ,2008,28(5) :10～19
[25] 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.西安建筑科技大学学报,2008,40(5) :648～653 Men J J,Shi Q X,Chen X H.Seismic damage of high buildings caused in the remote areas from epicenter and aseismic design suggestions.J.Xian Univ.of Arch.& Tech.(in Chinese),2008,40(5) :648～653
[26] 白家荣,史庆轩,陈曦虎等.汶川大地震西安市中小学建筑的震害调查和分析.水利与建筑工程学报,2009,7(2) :30～32+47 Bai J R,Shi Q X,Chen X H? et al.Investigation and analysis on seismic damage of primary and middle school buildings in Xi' an city under Wenchuan large earthquake.Journal of Water Resources and Architectural Engineering (in Chinese),2009,7(2) :30～32 + 47
[27] Somerville P G.Emerging art:earthquake ground motion.In:Dakolas P,et al.eds." Proceedings-Geotechnical Earthquake Engineering and Soil Dynamics Ⅲ".ASCE Speciality Conf.Special Pub.75,Seattle,WA,1～38
[28] Stewart J P,Chiou S J,Bray J D,et al.Ground motion evaluation procedures for performance-based design.PEER Report 2001/09． Pacific Earthquake Engineering Research Center,College of Engineering,University of California,Berkeley
[29] 中华人民共和国建设部.GB 50011-2001,建筑抗震设计规范.北京:中国建筑工业出版社,2001 Ministry of Construction of the People s Republic of China.GB 50011-2001,Code for Seismic Design of Buildings (in Chinese).Beijing:China Architecture & Building Press,2001
[30] 朱元详,李航飞,孙东晓.5·12汶川地震后陕西宝鸡陈仓区建筑物震害调查与分析.建筑科学与工程学报,2009,26(2) :116～120 Zhu Y X,Li H F,Sun D X.Damage investigation and analysis of buildings in Chencang county of Baoji city,Shanxi province after "5· 12"Wenchuan earthquake.Journal of Architecture and Civil Engineering (in Chinese),2009,26 (2) :116～120
[2] 孙小鹏,冯伯林,张战怀.深软土场地上高层住宅的地震安全 性问题.地震学刊,1999,3:1～5 Sun X P,Feng B L,Zhang Z H.Seismic safe problem of high building on deep soft site.Journal of Seismology (in Chinese),1999,3:1～5
[3] Bala A,Grecu B,Ciugudean V,Raileanu V.Dynamic properties of the Quaternary sedimentary rocks and their influence on seismic site effect:case study in Bucharest city, Romania.Soil Dynamic and Earthquake Engineering ,2009 ,29(1) :144～154
[4] 袁丽霞.场地土对地震波的放大作用.世界地震工程,2003,19(1) :113～120 Yuan L X.The amplifying effect of ground soil to earthquake wave.World Earthquake Engineering (in Chinese),2003,19(1) :113～120
[5] Borcherdt R D.Effects of local geology on ground motion near San Francisco Bay.Bull.Seism.Soc.Am.,1970,60(1) :29～61
[6] Andrews D J.Objective determination of source parameters and similarity of earthquakes of different size.In:Das S,Boatwright J,Scholz C H eds.Earthquake Source Mechanics.American Geophysical Union,Washington D.C.,1986,259～268
[7] Field E H,Jacob K H.A comparison and test of various site-response estimation techniques,including three that are not reference-site dependent.Bull.Seism.Soc.Am.1995,85(4) :1127～1143
[8] 章文波,谢礼立,郭明珠.利用强震记录分析场地的地震反应.地震学报,2001,23(6) :604～614 Zhang W B,Xie L L,Guo M Z.Estimation on site amplification from different methods using strong motion data obtained in Tangshan,China.Acta Seismologica Sinica (in Chinese),2001,23(6) :604～614
[9] Lermo J,Chrivez-Garcia F J.Site effect evaluation using spectral ratios with only one station.Bull.Seism.Soc.Am.,1993,83(5) :1574～1594
[10] Bonilla L F,Steidl J H,Lindley G T,et al.Site amplification in the San Fernando valley,California:variability of site-effect estimation using the S-Wave,Coda,and H/V Methods.Bull.Seism.Soc.Am.,1997,87(3) :710～730
[11] Atkinson G M,Cassidy J F.Integrated use of seismograph and strong-motion data to determine soil amplification:response of the Fraser River Delta to the Duvall and Georgia Strait earthquake.Bull.Seism.Soc.Am.,2000,90 (4) :1028～1040
[12] Malagnini L,Mayeda K,Akinci A,et al.Estimating absolute site effects.Bull.Seism.Soc.Am.,2004,94(4) :576～590
[13] Sokolov V,Loh C H,Wen K L.Evaluation of generalized site response function for typical soil classes (B,C,and D) in Taiwan.Earthquake Spectra ,2004,20:1279～1316
[14] 李永善.西安地裂及渭河盆地活断层研究.北京:地震出版社,1992 Li Y S.Research on ground fissures in Xi an Region and active faults in Weihe Basin (in Chinese).Beijing:Seismological Press,1992
[15] 刘护军.渭河盆地的形成演化与东秦岭的隆升[博士论文].西安:西北大学,2004 Liu H J.Formation and evolution of the Weihe river basin and uplift of the eastern Qinling mountains [Ph.D.thesis](in Chinese).Xi'an:Northwest University,2004
[16] 胡孟春.渭河盆地的地质构造与构造地貌类型.地理研究,1989,8(4) :56～64 Hu M C.The relationship between the tectonic landforms and structure in the Weihe river basin.Geographic Research (in Chinese),1989,1989 ,8(4) :56～64
[17] 张宗祜.九曲黄河万里沙-黄河与黄土高原.北京:清华大学出版社,2000 Zhang Z H.Sands in ten thousand miles of Yellow river turning many times-Yellow River and Loess Plateau (in Chinese).Beijing:Tsinghua University Press,2000
[18] 王景明.渭河地堑断裂构造研究.地质论评,1984,30(3) :217～223 Wang J M.A study on the tectonics of the Weihe river graben.Geological Review (in Chinese) ,1984,30(3) :217～223
[19] 权新昌.渭河盒地断裂构造研究.中国煤田地质,2005,17(3) :1～4 Quan X C.Study on faulted structure of Weihe basin.Coal Geology of China (in Chinese),2005 ,17(3) :1～4
[20] 彭建兵.渭河断裂带的构造演化与地震活动.地震地质,1992,14(2) :113～120 Peng J B.Tectonic evolution and seismicity of Weihe fault zone.Seismology and Geology (in Chinese),1992,14(2) :113～120
[21] 韩恒悦,张逸,袁志祥.渭河断陷盆地带的形成演化及断块运动.地震研究,2002,25(4) :362～368 Han H Y,Zhang Y,Yuan Z X.The evolution of Weihe down-faulted basin and the movement of the fault blocks.Journal of Seismological Research (in Chinese) ,2002,25(4) :362～368
[22] 中国地震局震害防御司.汶川8． 0级地震未校正加速度记录.中国强震记录汇报.北京:地震出版社,2008,12(1) :1～302 Burean of Earthquake Damage Protection,CEA.Uncorrected acceleration records of Wenchuan earthquake (M_s8． 0) (in Chinese).Report on strong earthquake motion records in China.Beijing:Seismological Press,2008,12(1) :1～302
[23] Bard P Y.Effects of surface geology on ground motion:recent results and remaining issues.In:Duma,Editor.Proceedings of 10~(th) European Conference on Earthquake Engineering,Vienna,Austria,1995,305～323
[24] 袁一凡.四川汶川8． 0级地震损失评估.地震工程与工程振动.2008,28(5) :10～19 Yuan Y F.Loss assessment of Wenchuan earthquake.Journal of Earthquake Engineering and Engineering Vibration (in Chinese) ,2008,28(5) :10～19
[25] 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.西安建筑科技大学学报,2008,40(5) :648～653 Men J J,Shi Q X,Chen X H.Seismic damage of high buildings caused in the remote areas from epicenter and aseismic design suggestions.J.Xian Univ.of Arch.& Tech.(in Chinese),2008,40(5) :648～653
[26] 白家荣,史庆轩,陈曦虎等.汶川大地震西安市中小学建筑的震害调查和分析.水利与建筑工程学报,2009,7(2) :30～32+47 Bai J R,Shi Q X,Chen X H? et al.Investigation and analysis on seismic damage of primary and middle school buildings in Xi' an city under Wenchuan large earthquake.Journal of Water Resources and Architectural Engineering (in Chinese),2009,7(2) :30～32 + 47
[27] Somerville P G.Emerging art:earthquake ground motion.In:Dakolas P,et al.eds." Proceedings-Geotechnical Earthquake Engineering and Soil Dynamics Ⅲ".ASCE Speciality Conf.Special Pub.75,Seattle,WA,1～38
[28] Stewart J P,Chiou S J,Bray J D,et al.Ground motion evaluation procedures for performance-based design.PEER Report 2001/09． Pacific Earthquake Engineering Research Center,College of Engineering,University of California,Berkeley
[29] 中华人民共和国建设部.GB 50011-2001,建筑抗震设计规范.北京:中国建筑工业出版社,2001 Ministry of Construction of the People s Republic of China.GB 50011-2001,Code for Seismic Design of Buildings (in Chinese).Beijing:China Architecture & Building Press,2001
[30] 朱元详,李航飞,孙东晓.5·12汶川地震后陕西宝鸡陈仓区建筑物震害调查与分析.建筑科学与工程学报,2009,26(2) :116～120 Zhu Y X,Li H F,Sun D X.Damage investigation and analysis of buildings in Chencang county of Baoji city,Shanxi province after "5· 12"Wenchuan earthquake.Journal of Architecture and Civil Engineering (in Chinese),2009,26 (2) :116～120
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