近断层地震动破裂向前方向性与滑冲效应对典型地铁车站结构动力响应的影响
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摘要
以台湾集集地震的近断层地震动记录TCU051-EW、TCU052-EW、TCU054-EW、TCU068-EW、TCU068-NS、TCU082-EW作为输入,使用有限差分程序FLAC对北京市拱形断面结构形式的单层三跨典型地铁车站进行了水平向弹塑性动力时程分析,研究了近断层地震动破裂向前方向性与滑冲效应引起的两种不同形式地震动对典型地铁车站结构动力响应的影响。计算结果表明:虽然破裂向前方向性效应与滑冲效应的输入地震动峰值加速度设置相同,但由滑冲效应地震动引起的结构相对水平位移差、峰值加速度及地震应力明显大于由破裂向前方向性效应地震动引起的结构相对水平位移差、加速度及地震应力,滑冲效应地震动较向前方向性效应地震动对地下结构的破坏更具危害性;输入破裂向前方向性效应近断层地震动时,拱形中跨顶板中部、边跨拱形顶板中部及中柱上端的水平方向加速度峰值均大于结构底板及中柱下端、底板中心等部位水平方向加速度峰值,即破裂向前方向效应地震动对结构上端的加速度反应特性具有放大作用,而输入滑冲效应近断层地震动时,结构上端水平方向加速度峰值却均小于结构下端水平方向加速度峰值,即滑冲效应地震动对结构上端的加速度反应特性具有减小作用,意味破裂向前方向性效应地震动造成结构上端动力响应较大,而滑冲效应地震动会使得结构底部动力响应较大。
Near-fault ground motion records of TCU051-EW,TCU052-EW,TCU054-EW,TCU068-EW,TCU068-NS,TCU082-EW from the Chi-Chi earthquake in Taiwan were selected as seismic inputs,and then time history analysis of elasto-plastic seismic responses of a single-layer three-span representative subway station with arched cross section in Beijing were carried out using finite difference procedure FLAC.The influence of two different kinds of near-fault ground motion caused by rupture forward directivity and fling step on the dynamic responses of the representative subway station structure was studied.It was shown that,although seismic peak ground accelerations of rupture forward directivity and fling step were set as the same,the relative horizontal displacement,the peak acceleration and the seismic stress of the structure caused by fling-step ground motion are significantly larger than those caused by rupture forward directivity ground motion,which implied that the fling-step ground motion caused more severe damage to underground structures than the forward directivity ground motion did;when the seismic input was rupture forward directivity ground motion,the middle positions of arched roofs of middle spans,the middle positions of arched roofs of side spans,and the top positions of columns had larger horizontal accelerations than the bottom of the structure did,which meant the horizontal acceleration of the top of the structure was amplified under rupture forward directivity ground motion;when the seismic input was fling-step ground motion,the top of the structure had smaller horizontal accelerations than the bottom of the structure did,which meant the horizontal acceleration of the top of the structure was reduced under the fling-step ground motion.The rupture forward directivity ground motion had more severe dynamic response on the top of the structure,while the fling-step ground motion had more severe dynamic response at the bottom of the structure.
Near-fault ground motion records of TCU051-EW,TCU052-EW,TCU054-EW,TCU068-EW,TCU068-NS,TCU082-EW from the Chi-Chi earthquake in Taiwan were selected as seismic inputs,and then time history analysis of elasto-plastic seismic responses of a single-layer three-span representative subway station with arched cross section in Beijing were carried out using finite difference procedure FLAC.The influence of two different kinds of near-fault ground motion caused by rupture forward directivity and fling step on the dynamic responses of the representative subway station structure was studied.It was shown that,although seismic peak ground accelerations of rupture forward directivity and fling step were set as the same,the relative horizontal displacement,the peak acceleration and the seismic stress of the structure caused by fling-step ground motion are significantly larger than those caused by rupture forward directivity ground motion,which implied that the fling-step ground motion caused more severe damage to underground structures than the forward directivity ground motion did;when the seismic input was rupture forward directivity ground motion,the middle positions of arched roofs of middle spans,the middle positions of arched roofs of side spans,and the top positions of columns had larger horizontal accelerations than the bottom of the structure did,which meant the horizontal acceleration of the top of the structure was amplified under rupture forward directivity ground motion;when the seismic input was fling-step ground motion,the top of the structure had smaller horizontal accelerations than the bottom of the structure did,which meant the horizontal acceleration of the top of the structure was reduced under the fling-step ground motion.The rupture forward directivity ground motion had more severe dynamic response on the top of the structure,while the fling-step ground motion had more severe dynamic response at the bottom of the structure.
引文
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[11]杨迪雄,赵岩,李刚.近断层地震动运动特征对长周期结构地震响应的影响分析[J].防灾减灾工程学报,2007,27(2):133-140.
[12]熊良宵,李天斌,刘勇.隧道地震响应数值模拟研究[J].地质力学学报,2007,13(3):255-260.
[2]陈磊,陈国兴.近断层强地震动下双层竖向重叠地铁隧道的地震反应[J].防灾减灾工程学报,2008(4):399-408.
[3]卢志杰.隧道受震反应分析之研究[D].台湾:中央大学,2009:1-4.
[4]陈磊,陈国兴.近场和远场地震动作用下双层竖向重叠地铁隧道的地震反应比较[J].中国铁道科学,2010,31(1):79-85.
[5]刘洋.近断层地铁隧道地震作用下动力响应数值模拟研究[D].北京:北京交通大学,2009:70-85.
[6]王海云,谢礼立.近断层强地震动的特点[J].哈尔滨工业大学学报,2006,38(12):2070-2076.
[7]Kalkan E,Kunnath S K.Effects of fling step and forward directivity on seismic response of buildings[J].Earthquake Spectra,2006,22(2):367-390.
[8]杨迪雄,赵岩.近断层地震动破裂向前方向性与滑冲效应对隔震建筑结构抗震性能的影响[J].地震学报,2010,32(5):579-587.
[9]胡曦波.北京地铁五号线东单站暗挖隧道施工方案[J].隧道建设,2006,26(1):44-48.
[10]刘启方,袁一凡,金星,丁海平.近断层地震动的基本特征[J].地震工程与工程振动,2006,26(1):1-10.
[11]杨迪雄,赵岩,李刚.近断层地震动运动特征对长周期结构地震响应的影响分析[J].防灾减灾工程学报,2007,27(2):133-140.
[12]熊良宵,李天斌,刘勇.隧道地震响应数值模拟研究[J].地质力学学报,2007,13(3):255-260.
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