地下水位对黄土土层地震动影响初探
|
摘要
场地条件对地震地面运动的影响很大,而对于黄土地区地震地面运动规律又有其自身的特性。鉴于兰州市区地下水位的不断上升,本文选取典型黄河南岸Ⅱ级阶地黄土场地,假设水位逐次提高1m,通过土层地震反应分析计算,分析地下水位上升对地表峰值加速度及反应谱的影响。结果表明:随着地下水位的不断上升,地表峰值加速度及土层地震动放大作用都有减小趋势,地下水的上升一定程度上对地表加速度峰值具有减震作用;但场地的特征周期却有增大趋势,平台范围越来越宽,反应谱双峰现象越来越显著,尤其当水位上升较多(文中11m),在罕遇地震动作用下对所有结构物加震显著,在常遇地震动和设计地震动作用下对自振周期0.7～1.3s结构物加震明显,应引起重视。
The effect of site conditions on earthquake ground motion is remarkable,and the earthquake ground motion in loess region has its own characteristics.In view of the rising groundwater of Lanzhou,this paper selects a typical loess site on second terraces of Yellow River,supposes groundwater will rise 1m one time,and analyzes the effect of groundwater rise on peak ground acceleration and acceleration response spectrum by soil seismic response analysis.The following conclusions can be drawn:the higher the groundwater level,the less the peak ground acceleration and amplification factor will be.Groundwater rise can reduce the effect of ground motion to a certain extent.But the characteristic period becomes longer,the flat portion of response spectrum becomes wider,and the two-peak phenomena are more significant.Especially when the groundwater rises more(11m in this paper),the accelerations of the loess site amplify significantly under seldom occurring ground motions,the accelerations of the structures on the loess site,the natural periods of which are in the range of 0.7～1.3 s,increase under frequently occurring ground motions and design ground motion.Attention should be paid to this.
The effect of site conditions on earthquake ground motion is remarkable,and the earthquake ground motion in loess region has its own characteristics.In view of the rising groundwater of Lanzhou,this paper selects a typical loess site on second terraces of Yellow River,supposes groundwater will rise 1m one time,and analyzes the effect of groundwater rise on peak ground acceleration and acceleration response spectrum by soil seismic response analysis.The following conclusions can be drawn:the higher the groundwater level,the less the peak ground acceleration and amplification factor will be.Groundwater rise can reduce the effect of ground motion to a certain extent.But the characteristic period becomes longer,the flat portion of response spectrum becomes wider,and the two-peak phenomena are more significant.Especially when the groundwater rises more(11m in this paper),the accelerations of the loess site amplify significantly under seldom occurring ground motions,the accelerations of the structures on the loess site,the natural periods of which are in the range of 0.7～1.3 s,increase under frequently occurring ground motions and design ground motion.Attention should be paid to this.
引文
[1]薄景山,李秀领,刘红帅.土层结构对地表加速度峰值的影响[J].地震工程与工程振动,2003,23(03):35-40.BO Jingshan,LI Xiuling,LIU Hongshuai.Effects of soil layer construction on peak accelerations of ground motions[J].Journal of Earthquake En-gineering and Engineering Vibration,2003,23(03):35-40.(in Chinese)
[2]薄景山,李秀领,李山有.场地条件对地震动影响研究的若干进展[J].世界地震工程,2003,19(02):11-15.BO Jingshan,LI Xiuling,LI Shanyou.Some progress of study on the effect of site conditions on ground motion[J].World Earthquake Engineering,2003,19(02):11-15.(in Chinese)
[3]王兰民,石玉成,刘旭,等.黄土动力学[M].北京:地震出版社,2003:282-331.WANG Lanmin,SHI Yucheng,LIU Xu,et al.Loess dynamics[M].Beijing:Seismological Press,2003:282-331.(in Chinese)
[4]中国选矿技术网,地下水位上升威胁兰州城市安全[EB/OL].2008-04-15.[2012-04-25].Beneficiation technology web of China.Urban safety threaten by groundaater rise[EB/OL].(2008-04-15)[2012-04-25].
[5]GB50011-2010建筑抗震设计规范[S].北京:中国建筑工业出版社,2010.GB50011-2010 Code for Seismic Design of Buildings[S].Beijing:China Architecture and Building Press,2010.(in Chinese)
[6]童华炜,朱博鸿.增湿对黄土动剪模量及阻尼比的影响[C]//《第三届全国土动力学学术会议文集》.上海:同济大学出版社,1990.117～120.TONG Huawei,ZHU Bohong.Effect of wetting on the loess dynamicshear modulus and damping ratio[C]//Corpus of Third National Soil DynamicConference.Shanghai:Tongji University Press,1990,117-120.
[7]李启鹞.黄土的动三轴和原位波速试验的现状[C]//《第三届全国土动力学学术会议文集》.上海:同济大学出版社,1990,111-116.LI Qiyao.Status quo of dynamic triaxial test and wave velocity test[C]//Corpus of Third National Soil Dynamics Conference.Shanghai:Tongji Uni-versity Press,1990,111-116.
[8]袁晓铭,孙锐.常规土类动剪切模量比和阻尼比试验研究[J].地震工程与工程振动,2000,20(04):133-138.YUAN Xiaoming,SUN Rui.Laboratory experimental study on dynamic shear modulus ratio and damping ratio of soils[J].Journal of EarthquakeEngineering and Engineering Vibration,2000,20(04):133-138.(in Chinese)
[9]廖振鹏.地震小区划-理论与实践[M].北京:地震出版社,1989:196-206.LIAO Zhenpeng.Seismic microzonation-theory and practice[M].Beijing:Seismological Press,1989.
[10]王亚勇.建筑抗震设计规范算例[M].北京:中国建筑工业出版社,2006.WANG Yayong.Examples of seismic design code of buildings[M].Beijing:China Architecture&Building Press,2006.
[11]胡仲有,骆亚生,李焱.不同地区黄土阻尼比变化特性试验研究[J].地震工程与工程振动,2010,30(2):169-174.HU Zhongyou,LUO Yasheng,LI Yan.Experimental study on damping ratio variation characteristics of loess in different areas[J].Journal ofEarthquake Engineering and Engineering Vibration,2010,30(2):169-174.(in Chinese)
[12]李平,薄景山,孙有为,等.场地类型对反应谱平台值的影响[J].地震工程与工程振动,2011,31(1):27-31.LI Ping,BO Jingshan,SUN Youwei,et al.Effects of site types on flat section values of response spectra[J].Journal of Earthquake Engineeringand Engineering Vibration,2011,31(1):27-31.(in Chinese)
[2]薄景山,李秀领,李山有.场地条件对地震动影响研究的若干进展[J].世界地震工程,2003,19(02):11-15.BO Jingshan,LI Xiuling,LI Shanyou.Some progress of study on the effect of site conditions on ground motion[J].World Earthquake Engineering,2003,19(02):11-15.(in Chinese)
[3]王兰民,石玉成,刘旭,等.黄土动力学[M].北京:地震出版社,2003:282-331.WANG Lanmin,SHI Yucheng,LIU Xu,et al.Loess dynamics[M].Beijing:Seismological Press,2003:282-331.(in Chinese)
[4]中国选矿技术网,地下水位上升威胁兰州城市安全[EB/OL].2008-04-15.[2012-04-25].Beneficiation technology web of China.Urban safety threaten by groundaater rise[EB/OL].(2008-04-15)[2012-04-25].
[5]GB50011-2010建筑抗震设计规范[S].北京:中国建筑工业出版社,2010.GB50011-2010 Code for Seismic Design of Buildings[S].Beijing:China Architecture and Building Press,2010.(in Chinese)
[6]童华炜,朱博鸿.增湿对黄土动剪模量及阻尼比的影响[C]//《第三届全国土动力学学术会议文集》.上海:同济大学出版社,1990.117～120.TONG Huawei,ZHU Bohong.Effect of wetting on the loess dynamicshear modulus and damping ratio[C]//Corpus of Third National Soil DynamicConference.Shanghai:Tongji University Press,1990,117-120.
[7]李启鹞.黄土的动三轴和原位波速试验的现状[C]//《第三届全国土动力学学术会议文集》.上海:同济大学出版社,1990,111-116.LI Qiyao.Status quo of dynamic triaxial test and wave velocity test[C]//Corpus of Third National Soil Dynamics Conference.Shanghai:Tongji Uni-versity Press,1990,111-116.
[8]袁晓铭,孙锐.常规土类动剪切模量比和阻尼比试验研究[J].地震工程与工程振动,2000,20(04):133-138.YUAN Xiaoming,SUN Rui.Laboratory experimental study on dynamic shear modulus ratio and damping ratio of soils[J].Journal of EarthquakeEngineering and Engineering Vibration,2000,20(04):133-138.(in Chinese)
[9]廖振鹏.地震小区划-理论与实践[M].北京:地震出版社,1989:196-206.LIAO Zhenpeng.Seismic microzonation-theory and practice[M].Beijing:Seismological Press,1989.
[10]王亚勇.建筑抗震设计规范算例[M].北京:中国建筑工业出版社,2006.WANG Yayong.Examples of seismic design code of buildings[M].Beijing:China Architecture&Building Press,2006.
[11]胡仲有,骆亚生,李焱.不同地区黄土阻尼比变化特性试验研究[J].地震工程与工程振动,2010,30(2):169-174.HU Zhongyou,LUO Yasheng,LI Yan.Experimental study on damping ratio variation characteristics of loess in different areas[J].Journal ofEarthquake Engineering and Engineering Vibration,2010,30(2):169-174.(in Chinese)
[12]李平,薄景山,孙有为,等.场地类型对反应谱平台值的影响[J].地震工程与工程振动,2011,31(1):27-31.LI Ping,BO Jingshan,SUN Youwei,et al.Effects of site types on flat section values of response spectra[J].Journal of Earthquake Engineeringand Engineering Vibration,2011,31(1):27-31.(in Chinese)
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心