单一均质土覆盖层厚度对地表峰值加速度和反应谱平台值的影响
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摘要
选择粘土、粉土、砂土、砾石4类土场地构造了140个单一均质土剖面,输入峰值分别为50、100、150、200、300Gal的各3条人工合成地震动时程,使用一维等效线性波动法,进行了土层地表地震反应计算,并对计算得到的地表峰值加速度和反应谱平台值做了统计分析和讨论。结果表明:不同土类地表峰值加速度和反应谱平台值随覆盖层增大达到最大值的厚度不同;不同幅值的基底输入,不同土类的覆盖层情况下,地表峰值加速度相对于基岩值加速度的放大倍数并不具有规律性,同是Ⅱ类场地,中软和中硬场地土条件下放大倍数的差异也是明显的。
We build 140 single homogeneous soil profiles by using four types of soil,such as clay,silt,sand and gravel.Then using one-dimensional equivalent linear wave method,we calculate the seismic response of soil surface when inputting 3 time histories of synthetic ground motion with the peak of 50,100,150,200,300 Gal,and make a statistical analysis of calculated surface peak acceleration,platform value of the acceleration response spectrum.The results show that the surface peak acceleration,platform value of the acceleration response spectrum of different soil increase with thickness of overburden layer,then gradually decreased after reaching the peak.The thickness corresponding to the maximum peak is different.When inputting the time histories of synthetic ground motion with different peak or under condition of overburden layer with different soil,amplification factor of surface peak acceleration is less regularity than that of bedrock peak acceleration.The difference of amplification factor between the medium soft site and medium hard site which are in the same site typeⅡ is obvious.
We build 140 single homogeneous soil profiles by using four types of soil,such as clay,silt,sand and gravel.Then using one-dimensional equivalent linear wave method,we calculate the seismic response of soil surface when inputting 3 time histories of synthetic ground motion with the peak of 50,100,150,200,300 Gal,and make a statistical analysis of calculated surface peak acceleration,platform value of the acceleration response spectrum.The results show that the surface peak acceleration,platform value of the acceleration response spectrum of different soil increase with thickness of overburden layer,then gradually decreased after reaching the peak.The thickness corresponding to the maximum peak is different.When inputting the time histories of synthetic ground motion with different peak or under condition of overburden layer with different soil,amplification factor of surface peak acceleration is less regularity than that of bedrock peak acceleration.The difference of amplification factor between the medium soft site and medium hard site which are in the same site typeⅡ is obvious.
引文
薄景山,李秀领,李山有.2003a.场地条件对地震动影响研究的若干进展[J].世界地震工程,19(2):11-15.
薄景山,李秀领,刘德东,等.2003b.土层结构对反应谱平台值的影响[J].地震工程和工程振动,23(4):29-33.
薄景山,李秀领,刘红帅.2003c.土层结构对地表加速度峰值的影响[J].地震工程和工程振动,23(3):29-33.
冯希杰,金学申.2001.场地土对基岩峰值加速度放大效应分析[J].工程地质学报,9(4):385-388.
胡聿贤.2006.地震工程学[M].北京:地震出版社.
李媛媛,徐扬,吴东.2006.覆盖层厚度对反应谱峰值的影响[J].地震地磁观测与研究,27(4):33-38.
廖振鹏,李小军.1989.地表土层地震反应的等效线性化解法[A]//廖振鹏.地震小区化—理论与实践[M].北京:地震出版社.
刘红帅,薄景山,吴兆营,等.2005.土体参数对地表加速度峰值和反应谱的影响[J].地震研究,28(2):167-171.
田启文.2009.工程地震学基础[M].防灾科技学院教材.
DB001-94,工程场地地震安全性评价工作规范[S].
GB50011-2010,建筑抗震设计规范[S].
薄景山,李秀领,刘德东,等.2003b.土层结构对反应谱平台值的影响[J].地震工程和工程振动,23(4):29-33.
薄景山,李秀领,刘红帅.2003c.土层结构对地表加速度峰值的影响[J].地震工程和工程振动,23(3):29-33.
冯希杰,金学申.2001.场地土对基岩峰值加速度放大效应分析[J].工程地质学报,9(4):385-388.
胡聿贤.2006.地震工程学[M].北京:地震出版社.
李媛媛,徐扬,吴东.2006.覆盖层厚度对反应谱峰值的影响[J].地震地磁观测与研究,27(4):33-38.
廖振鹏,李小军.1989.地表土层地震反应的等效线性化解法[A]//廖振鹏.地震小区化—理论与实践[M].北京:地震出版社.
刘红帅,薄景山,吴兆营,等.2005.土体参数对地表加速度峰值和反应谱的影响[J].地震研究,28(2):167-171.
田启文.2009.工程地震学基础[M].防灾科技学院教材.
DB001-94,工程场地地震安全性评价工作规范[S].
GB50011-2010,建筑抗震设计规范[S].
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