三维地形中地震动的频域特征——以芦山地区为例
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摘要
地形条件对局部震害分布有重要影响。本文选择地形起伏剧烈的芦山地区,采用三维谱元法模拟地震波传播。研究了该地区地震动的频谱特征。计算了测线上位于山顶和山谷的台站傅里叶频谱,并研究了各自的谱值和谱值比特征。分析结果表明:山顶包含了较高的频谱;山谷包含了较低的频谱;山顶上的频谱值高于山谷的频谱值;并且地形对水平分量的影响更大。同时,进一步从频谱中提取了峰值放大比和峰值频率2个参数,分析了其在芦山地形中的分布特征。结果显示,山顶对应了较大的峰值放大比和峰值频率,而山谷则对应了较低的峰值放大比和峰值频率。
The topography plays an important role in local disaster distribution. In this article, Lushan area with steep topography is chosen as our research area. We use 3-D spectral element method to simulate seismic wave propagation and analyze the spectrum of strong ground motion. We calculate the spectrum of velocity time history of stations on ridge and valley of selected profiles. The results show that the spectrum on ridge contains higher frequency and spectrum on valley contains lower frequency. Spectrum on ridge are larger than spectrum on valley,and the surface irregularity has greater effect on horizontal components. Moreover, we calculate the peak amplification ratio and peak frequency from the spectrum and analyze their distribution on Lushan topography. The results show that the ridge has larger amplification ratio and peak frequency while the valley has lower ratio and peak frequency.
The topography plays an important role in local disaster distribution. In this article, Lushan area with steep topography is chosen as our research area. We use 3-D spectral element method to simulate seismic wave propagation and analyze the spectrum of strong ground motion. We calculate the spectrum of velocity time history of stations on ridge and valley of selected profiles. The results show that the spectrum on ridge contains higher frequency and spectrum on valley contains lower frequency. Spectrum on ridge are larger than spectrum on valley,and the surface irregularity has greater effect on horizontal components. Moreover, we calculate the peak amplification ratio and peak frequency from the spectrum and analyze their distribution on Lushan topography. The results show that the ridge has larger amplification ratio and peak frequency while the valley has lower ratio and peak frequency.
引文
Athanasopoulos G.A.,Pelekis P.C.,Xenaki V.C.,2001.Topography Effects in the Athens 1999 Earthquake:the Case of Hotel DEKELIA.See:Proceedings of the Fourth International Conference on Recent Advances in Geotechniques and Earthquake Engineering Soil Dynanics,San Diego,California,2001.Paper No.10.42.
Bard P.Y.,Riepl-Thomas J.,1999.Wave propagation in complex geological structures and their effects on strong ground motion.In Wave Motion in Earthquake Engineering,Kausel E.,Manolis GD(eds.).International Series Advances in Earthquake Engineering,WIT:Boston,37 —95.
Boore D.M.,1972.A note on the effect of simple topography on seismic SH waves.Bulletin of the Seismological Society of America,62 (1 ):275 —84.
Borcherdt R.D.,1970.Effects of local geology on ground motion near San Francisco Bay.Bulletin of the Seismological Society of America,60 (1 ):29 —61.
Celebi M.,1987.Topographical and geological amplifications determined from strong-motion and aftershock records of the 3 March 1985 Chile earthquake.Bulletin of the Seismological Society of America,77 (4 ):1147—1167.
Faccioli E.,Maggio F.,Paolucci R.et al.,1997.2D and 3D elastic wave propagation by a pseudo-spectral domain decomposition method.Journal of Seismology,1 (3 ):237 —251.
Geli L.,Bard P.Y.,Jullien B.,1988.The effect of topography on earthquake ground motion:a review and new results.Bulletin of the Seismological Society of America,78 :42 —63.
Komatitsch D.,Vilotte J.P.,1998.The spectral element method:an efficient tool to simulate the seismic response of2 D and 3D geological structures.Bulletin of the Seismological Society of America,88 (2 ):368 —392.
Liao Z.P.,Wong H.L.,Yang B.P.et al.,1984.A transmitting boundary for transient wave analysis.Scientia Sinica,27 (10 ):1063—1076.
Nakamura Y.,1989.A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface.Railway Technical Research Institute,Quarterly Reports.
Paolucci R.,2002.Amplification of earthquake ground motion by steep topographic irregularities.Earthquake Engineering&Structural Dynamics,31 (10 ):1831—1853.
Patera A.T.,1984.A spectral element method for fluid dynamics:laminar flow in a channel expansion.Journal of Computational Physics,54 (3 ):468 —488.
Pedersen H.,Le Brun B.,Hatzfeld D.et al.,1994.Ground motion amplitude across ridges.Bulletin of the Seismological Society of America,84 :1786—1800.
Bard P.Y.,Riepl-Thomas J.,1999.Wave propagation in complex geological structures and their effects on strong ground motion.In Wave Motion in Earthquake Engineering,Kausel E.,Manolis GD(eds.).International Series Advances in Earthquake Engineering,WIT:Boston,37 —95.
Boore D.M.,1972.A note on the effect of simple topography on seismic SH waves.Bulletin of the Seismological Society of America,62 (1 ):275 —84.
Borcherdt R.D.,1970.Effects of local geology on ground motion near San Francisco Bay.Bulletin of the Seismological Society of America,60 (1 ):29 —61.
Celebi M.,1987.Topographical and geological amplifications determined from strong-motion and aftershock records of the 3 March 1985 Chile earthquake.Bulletin of the Seismological Society of America,77 (4 ):1147—1167.
Faccioli E.,Maggio F.,Paolucci R.et al.,1997.2D and 3D elastic wave propagation by a pseudo-spectral domain decomposition method.Journal of Seismology,1 (3 ):237 —251.
Geli L.,Bard P.Y.,Jullien B.,1988.The effect of topography on earthquake ground motion:a review and new results.Bulletin of the Seismological Society of America,78 :42 —63.
Komatitsch D.,Vilotte J.P.,1998.The spectral element method:an efficient tool to simulate the seismic response of2 D and 3D geological structures.Bulletin of the Seismological Society of America,88 (2 ):368 —392.
Liao Z.P.,Wong H.L.,Yang B.P.et al.,1984.A transmitting boundary for transient wave analysis.Scientia Sinica,27 (10 ):1063—1076.
Nakamura Y.,1989.A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface.Railway Technical Research Institute,Quarterly Reports.
Paolucci R.,2002.Amplification of earthquake ground motion by steep topographic irregularities.Earthquake Engineering&Structural Dynamics,31 (10 ):1831—1853.
Patera A.T.,1984.A spectral element method for fluid dynamics:laminar flow in a channel expansion.Journal of Computational Physics,54 (3 ):468 —488.
Pedersen H.,Le Brun B.,Hatzfeld D.et al.,1994.Ground motion amplitude across ridges.Bulletin of the Seismological Society of America,84 :1786—1800.
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