地震行波作用下山脊震裂现象的物理机制探讨
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摘要
地震作用下的场地反应及其破坏机理一直是地震学和地震工程学的研究热点,汶川大地震发生后高海拔山区产生的独特地质灾害现象已经超出了我们传统理论范围。针对汶川地震极震区和强震区普遍发生的山体"溃崩"及上部"震裂"现象,运用波动理论进行理论推导,在线弹性假设下将行波应力方程在临空面的反射和入射波叠加,推导出总应力表达式在距坡顶λ/4处会出现应力放大一倍的结论,为高烈度地震山区中出现的"溃崩"、"震裂"现象提供一种理论解释。同时结合汶川地震极震区监测台站记录和现场面波测试结果,根据本文理论对汶川地震中山体"溃崩"、"震裂"的具体范围进行预测,该理论结果可为高烈度地震山区公路、铁路的选线提供建议。
Site response and its damage mechanism under earthquake effect is the research focus of seismology and earthquake engineering.Unique geological hazards phenomenon of high altitude mountain after the Wenchuan earthquake is beyond the traditional theory.According to the mountain body collapse and mountain top shattering phenomenon that are generally occurred in Wenchuan epicentral and meizoseismal earthquake areas,theoretical derivation by wave theory is conducted.By stacking the stress equation of traveling seismic wave in the free surface which reflect and incident under linearly elastic hypothesis,conclusions are derived that the expression of the total stress will appear double amplification at λ / 4 from the top of the hill,which provide a theoretical explanation for the 2 phenomenon in high intensity earthquake areas.Combined with the record of monitoring stations in the epicentral area of Wenchuan earthquake,and based on theories in this paper,the specific scopes of mountain body collapse and mountain top shattering are predicted,and the theoretical results may provide advice for the road and railway line selection among high intensity earthquake mountain areas.
Site response and its damage mechanism under earthquake effect is the research focus of seismology and earthquake engineering.Unique geological hazards phenomenon of high altitude mountain after the Wenchuan earthquake is beyond the traditional theory.According to the mountain body collapse and mountain top shattering phenomenon that are generally occurred in Wenchuan epicentral and meizoseismal earthquake areas,theoretical derivation by wave theory is conducted.By stacking the stress equation of traveling seismic wave in the free surface which reflect and incident under linearly elastic hypothesis,conclusions are derived that the expression of the total stress will appear double amplification at λ / 4 from the top of the hill,which provide a theoretical explanation for the 2 phenomenon in high intensity earthquake areas.Combined with the record of monitoring stations in the epicentral area of Wenchuan earthquake,and based on theories in this paper,the specific scopes of mountain body collapse and mountain top shattering are predicted,and the theoretical results may provide advice for the road and railway line selection among high intensity earthquake mountain areas.
引文
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[2]刘洪兵,朱晞.地震中地形放大作用的观测和研究进展[J].世界地震工程,1999,15(3):20-25.
[3]AkiK.Local site effects on weak and strong groundmotion[J].Tectonophysics,1993,218:93-111.
[4]Steild JH.Site response in southern California for probabilisticseismic hazard analysis[J].Bull Seism.Soc.Am.,2000,90(6B):149-169.
[5]黄润秋.汶川8.0级地震触发崩滑灾害机制及其地质力学模式[J].岩土力学与工程学报,2009,28(6):1239-1249.
[6]Broili-Luciano.New knowledges on the geomorphology of thevaiom slide slip surfaces[J].Felsmechanik and Ingenieurgeolo-gie,1967,5(1):38-88.
[7]徐龙军,谢礼立.竖向地震动加速度反应谱特性[J].地震工程与工程振动,2007,27(6):17-23.
[8]冯文凯,许强,黄润秋.斜坡震裂变形力学机制初探[J].岩土力学与工程学报,2009,28(1):3124-3130.
[9]Bard P Y.Effects of surface geology on groundmotion:recent re-sults and remaining issues[C]//Proc.10th European Conference On Earthquate Engrg.Vienna,1994:305-323.
[10]戴俊.岩石动力学特性与爆破理论[M].北京:冶金工业出版社,2002:58-67.
[11]徐光兴,姚令侃,李朝红,等.边坡地震动力响应规律及地震动参数影响研究[J].岩土工程学报,2008,30(6):918-923.
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