地震研究

基于谱元法,采用4种不同倾角的盆地模型,研究了不同震源深度走滑地震非平面波入射时二维盆地放大规律,分析了盆地边缘放大的峰值及其位置与无量纲频率和盆地倾角的关系。结果表明:①随着震源深度的增大,水平方向上速度峰值比的最大值逐渐增大,在震源深度为10 km时达到最大,随后减小,且水平向和竖直向速度峰值比的最大值位置逐渐偏向盆地边缘。②震源深度较浅时,4种倾角的盆地在水平方向上的速度峰值比的最大值相差不大,差值始终小于1; 震源深度较深且频率较高时(η≥1),4种倾角盆地的速度峰值比的最大值相差很大,差值达到3。

Based on the spectral element method,four basin models with different dip angles are used to study the amplification law of the two-dimensional basin when non-plane waves caused by the strike-slip earthquake at different focal depths travel in the basin.The relationship between the maximum amplification,its position at the edge of the basin and the dimensionless frequency,dip angle of the basin is analyzed.The results show that:① With the increase of focal depth,the peak velocity ratio increases gradually in the horizontal direction,and reaches the maximum when focal depth is 10 km,and then decreases.And the position of the maximum peak velocity ratio in horizontal and vertical directions gradually becomes close to the edge of the basin.② When the focal depth is relatively shallow,there is little difference between the maximum ratios of the peak velocity in horizontal direction among four basin models with different dip angles,and the difference is always less than 1.When the focal depth is deep and the frequency is high(η≥1),the maximum ratios of the peak velocity vary greatly,and the maximum difference reaches 3.

引言
1 计算模型及方法
2 数据分析
3 结论

图1 计算模型及观测点位置<br/>Fig.1 Calculation model and the position of observing points

图1 计算模型及观测点位置
Fig.1 Calculation model and the position of observing points

表1 震源深度h及入射角范围θ<br/>Tab.1 Focal depth h and the range of incident angle θ

表1 震源深度h及入射角范围θ
Tab.1 Focal depth h and the range of incident angle θ

表2 盆地模型介质参数<br/>Tab.2 Media parameters of the basin model

表2 盆地模型介质参数
Tab.2 Media parameters of the basin model

图2 中心频率为0.4 Hz的Ricker子波速度时程(a)及傅立叶谱(b)<br/>Fig.2 The velocity time history(a)and the Fourier spectrum(b)of Ricker wavelet with center frequency of 0.4 Hz

图2 中心频率为0.4 Hz的Ricker子波速度时程(a)及傅立叶谱(b)
Fig.2 The velocity time history(a)and the Fourier spectrum(b)of Ricker wavelet with center frequency of 0.4 Hz

图3 45°倾角盆地速度时程(a)及PGV(b)<br/>Fig.3 Velocity time history(a)and PGV(b)of the basin with dip angle 45°

图3 45°倾角盆地速度时程(a)及PGV(b)
Fig.3 Velocity time history(a)and PGV(b)of the basin with dip angle 45°

图4 在6种无量纲频率下4种盆地倾角模型水平向(a)和竖直向(b)的速度峰值比分布<br/>Fig.4 Distribution of the ratios of peak velocity in horizontal(a)and vertical(b)direction at six dimensionless frequencies for four basin models with different dip angles

图4 在6种无量纲频率下4种盆地倾角模型水平向(a)和竖直向(b)的速度峰值比分布
Fig.4 Distribution of the ratios of peak velocity in horizontal(a)and vertical(b)direction at six dimensionless frequencies for four basin models with different dip angles

图5 45°倾角盆地的水平向(a)和竖直向(b)速度峰值比<br/>Fig.5 The ratio of peak velocity in the horizontal (a)and vertical(b)direction of the basin model with dip angle 45°

图5 45°倾角盆地的水平向(a)和竖直向(b)速度峰值比
Fig.5 The ratio of peak velocity in the horizontal (a)and vertical(b)direction of the basin model with dip angle 45°

图6 不同震源深度下4种不同倾角盆地速度峰值比最大值随η变化<br/>Fig.6 The maximum ratio of peak velocity of basin models with four dip angles varies with η at different focal depth

图6 不同震源深度下4种不同倾角盆地速度峰值比最大值随η变化
Fig.6 The maximum ratio of peak velocity of basin models with four dip angles varies with η at different focal depth

图7 不同震源深度、不同η下4种不同倾角盆地速度峰值比最大值所在盆地位置<br/>Fig.7 Location of the maximum ratio of the peak velocity of basin models with four dip angles in frequencies η at different focal depth

图7 不同震源深度、不同η下4种不同倾角盆地速度峰值比最大值所在盆地位置
Fig.7 Location of the maximum ratio of the peak velocity of basin models with four dip angles in frequencies η at different focal depth

丁海平,吕思东,于彦彦.2018.内源输入时盆地特征参数对盆地地震效应的影响[J].苏州科技大学学报(工程技术版),31(3):1-6.
郭明珠,谢礼立,凌贤长.2004.弹性介质面波地脉动单点谱比法研究[J].岩土工程学报,26(4):4.
李雪强.2011.沉积盆地地震效应研究[D].哈尔滨:中国地震局工程力学研究所.
廖树超,于彦彦,丁海平.2018.基于Lamb问题的谱元法和有限元法模拟精度比较[J].世界地震工程,34(3):190-198.
刘启方,于彦彦,章旭斌.2013.施甸盆地三维地震动研究[J].地震工程与工程振动,33(4):54-60.
刘启方.2020.1556年华县大地震地震动场模拟[J].自然灾害学报,29(5):3-12.
刘中宪,刘明珍,韩建斌.2017.近断层沉积盆地强地震动谱元模拟[J].世界地震工程,33(4):76-86.
严珍珍,张怀,杨长春,等.2009.汶川大地震地震波传播的谱元法数值模拟研究[J].中国科学:地球科学,39(4):393-402.
于彦彦,丁海平,刘启方.2020.盆地内外介质阻抗比对盆地地表地震动及次生Rayleigh面波的影响[J].岩土工程学报,42(4):667-677.
禹乐,于彦彦,丁海平.2020.内源作用下盆地倾角对地表地震动放大特征的影响[J].地震工程与工程振动,40(5):99-108.
张建经,朱传彬,张明,等.2014.地震入射角对盆地地震反应影响的数值分析[J].岩石力学与工程学报,33(S1):2720-2726.
Ayoubi P,Mohammadi K,Asimaki D.2020.A systematic analysis of basin effects on surface ground motion[J].Soil Dynamics and Earthquake Engineering,141:106490.
Chen K C.2003.Strong ground motion and damage in the Taipei basin from the Moho reflected seismic waves during the March 31,2002,Hualien,Taiwan earthquake[J].Geophysical Research Letters,30(11),doi:10.1029/2003GL017193,2003.
Kawase H,Aki K.1989.A study on the response of a soft basin for incident S,P,and Rayleigh waves with special reference to the long duration observed in Mexico City[J].Bulletin of the Seismological Society of America,79(5):1361-1382.
Kawase H.1996.The cause of the damage belt in Kobe:“the basin-edge effect,”constructive interference of the direct S-wave with the basin-induced diffracted/Rayleigh waves[J].Seismological Research Letters,67(5):25-34.
Komatitsch D,Vilotte J P.1999.Reply to comment by E Faccioli and A Quarteroni on “The spectral element method:An efficient tool to simulate the seismic response of 2D and 3D geological structures” by D Komatitsch and J-P Vilotte[J].Bulletin of the Seismological Society of America,89(1):332-334.
Komatitsch D.2012.Simulations of ground motion in the Los Angeles Basin based upon the spectral-element method[J].Bulletin of the Seismological Society of America,94(1):187-206.
PitarkaA,Irikura K.1996.Basin structure effects on long-period strong motions in the San Fernando Valley and the Los Angeles Basin from the 1994 Northridge earthquake and an aftershock[J].Bulletin of the Seismological Society of America,86(1B):672107.

备注

引言

1 计算模型及方法

2 数据分析

3 结论

期刊信息