山脉震中距对地震动山体地形效应影响研究
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摘要
地震动山体地形效应易加重山区震害,威胁山区基础设施安全,研究山脉震中距对山体地形效应的影响对山区基础设施建设有重要意义。基于谱元法,定量研究山脉与断层走向平行时,山脉震中距与震源埋深比值改变对山体地表响应的影响。结果表明:(1)0<△l/h<5时,迎侧坡面PGA小于背侧坡面PGA,坡面PGA放大系数可达1.7。△l/h≥5时,坡面PGA呈明显缩小现象;(2)△l/h≥5时,坡面PGD与PGA响应规律有明显差异,坡面PGD出现明显放大现象,PGD放大系数最大可达1.7。
The seismic hazard of mountain area is usually more severe than others because of hill topography effect,which threatens the security of infrastructure construction in mountain area.Studying the influence of mountain epicentral distance on hill topography effect makes great sense. The spectralelement method was used to study the influence of the ratio between mountain epicentral distance and focal depth on ground motion when mountain strike is parallel to fault strike,the achievements are as follows:(1)In the ranges of 0<△l/h<5,the overall level of PGA in source-proximal hillside is less than that in source-distal hillside,and the amplification factor of slope can reach 1.7. In the ranges of △l/h≥5,the PGA of slope is shrinked obviously.(2)In the ranges of △l/h≥5,the regularity of the PGD response is different from the regularity of PGA response in slope:The PGD of slope is amplified obviously,and the amplification factor can reach 1.7.
The seismic hazard of mountain area is usually more severe than others because of hill topography effect,which threatens the security of infrastructure construction in mountain area.Studying the influence of mountain epicentral distance on hill topography effect makes great sense. The spectralelement method was used to study the influence of the ratio between mountain epicentral distance and focal depth on ground motion when mountain strike is parallel to fault strike,the achievements are as follows:(1)In the ranges of 0<△l/h<5,the overall level of PGA in source-proximal hillside is less than that in source-distal hillside,and the amplification factor of slope can reach 1.7. In the ranges of △l/h≥5,the PGA of slope is shrinked obviously.(2)In the ranges of △l/h≥5,the regularity of the PGD response is different from the regularity of PGA response in slope:The PGD of slope is amplified obviously,and the amplification factor can reach 1.7.
引文
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[4]吴建平,黄媛,张天中,等.汶川MS8.0级地震余震分布及周边区域P波三维速度结构研究[J].地球物理学报,2009,52(2):320-328.
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[2]李孝波,薄景山,万卫,等.基岩地形对地震动影响研究[J].岩土工程学报,2017,39(3):460-468.
[3]王伟,刘必灯,刘欣,等.基于汶川MS8.0地震强震动记录的山体地形效应分析[J].地震学报,2015,37(3):452-462.
[4]吴建平,黄媛,张天中,等.汶川MS8.0级地震余震分布及周边区域P波三维速度结构研究[J].地球物理学报,2009,52(2):320-328.
[5]Brocher T M.Key elements of Regional Seismic Velocity Models for Long Period Ground Motion Simulations[J].Journal of Seismology,2008,12(2):217-221.
[6]Tromp,Jeroen.Theoretical Global Seismology[M].Chichester:Princeton University Press,1998.
[7]Komatitsch D,Tromp J.Introduction to the Spectral Element Method for Three-dimensional Seismic Wave Propagation[J].Geophysical Journal of the Royal Astronomical Society,2010,139(3):806-822.