Quantification of effects of geometry of sediment bedrock interface on ground motion in 3D basin with circular free surface

IF 0.9 4区地球科学 Q4 GEOCHEMISTRY & GEOPHYSICS

Geofizika Pub Date : 2015-06-30 DOI:10.15233/GFZ.2015.32.3

J. Narayan, Battan Kamal

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引用次数: 2

Abstract

This paper presents the effects of geometry of sediment bedrock interface (GSBI) of 3D basins with a circular outcropping free surface on the characteristics and the focusing of the basin-generated surface (BGS) waves and associated spatial variations of the average spectral amplification (ASA) and average aggravation factor (AAF). An increase of ASA towards the centre of the semispherical (SS-) basin as compared to the 2D basin revealed the focusing of the BGS-waves in the SS-basin. The obtained 2.8 times larger ASA at the centre of the SS-basin to that of 2D basin calls for a special attention in predicting the seismic hazard in such basins for earthquake engineering purposes. The analysis of the simulated results revealed that the amplitude amplification due to the focusing of the BGS-waves was highly affected by the GSBI. For example, the ASA at the centre of a trapezoidal basin with edge slope 20° was 50% larger than that at the centre of a trapezoidal basin with edge slope 45°. It is recommended to compute the AAF using the same components of ground motion as that of the incident wave to conservatively aggravate the ground motion to incorporate the 3D basin-effects in the seismic microzonation where it is over based on the 1D response of sediment column.

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三维圆形自由面盆地沉积物基岩界面几何形状对地面运动影响的定量分析

本文研究了具有圆形自由面的三维盆地沉积基岩界面(GSBI)几何形状对盆生面波(BGS)特征、聚焦及相关平均谱放大(ASA)和平均加重因子(AAF)空间变化的影响。相对于二维盆地，半球形盆地(SS-)向中心方向的ASA增加揭示了bgs波在SS-盆地的集中。在ss盆地中心获得的ASA是2D盆地的2.8倍，这需要特别注意在地震工程中预测此类盆地的地震危险性。模拟结果分析表明，GSBI对bgs波聚焦引起的振幅放大影响较大。例如，边缘坡度为20°的梯形盆地中心的ASA比边缘坡度为45°的梯形盆地中心的ASA大50%。建议采用与入射波相同的地震动分量来计算AAF，以保守地加重地震动，并根据沉积物柱的一维响应在地震微带中考虑三维盆地效应。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Geofizika 地学-地球化学与地球物理

CiteScore

1.60

自引率

0.00%

发文量

审稿时长

>12 weeks

期刊介绍： The Geofizika journal succeeds the Papers series (Radovi), which has been published since 1923 at the Geophysical Institute in Zagreb (current the Department of Geophysics, Faculty of Science, University of Zagreb). Geofizika publishes contributions dealing with physics of the atmosphere, the sea and the Earth''s interior.