地震研究

基于南海某岛礁的实际工程地质剖面图建立了海水-岛礁-地震耦合的岛礁模型,利用FLAC有限差分方法,分析了是否考虑海水作用2种情况下水平输入海底地震动时岛礁的场地地震反应规律。结果表明:①灰砂岛PGA放大效应显著,灰砂岛及外礁坪角点处PGA放大效应取得极大或极小值; ②考虑流固耦合及岛礁外部海水动力作用后,岛礁场地地震反应呈现与不考虑海水作用基本持平或降低的趋势; ③岛礁水平向加速度放大系数整体随输入地震动峰值的增大而减小,随着砂层深度的减小总体呈增大趋势。

Based on the actual engineering geological profile of a coral island in the South China Sea,a two-dimensional island model with seawater-island-seismic coupling is established.The FLAC finite difference method is used to analyze the seismic response of islands when horizontal input seafloor ground motions are considered in the two cases.The results show that:①The PGA amplification effect at lime-sand island is significant,and the PGA amplification effect at the corner point of the lime-sand island and outer reef have achieved a maximum or minimum value; ②Compared with ignoring seawater effects,after considering the fluid-solid coupling of seawater and the dynamic effects of seawater outside the islands,the seismic response of the islands show a flat or decreasing trend; ③The amplification factor of the horizontal acceleration of the island decrease with the increase of peak value of the input earthquake and generally increase as the decrease of the sand layer depth.

引言
1 珊瑚岛礁场地地震反应分析的模型及参数
2 海底地震动作用下岛礁场地反应特征分析
3 结论

图1 某珊瑚岛礁场地平面图(a)(据陈国兴等,2019)及岛礁计算模型(b)<br/>Fig.1 Plan of a coral island(a)(based on Chenet al,2019)and computational model of the island(b)

图1 某珊瑚岛礁场地平面图(a)(据陈国兴等,2019)及岛礁计算模型(b)
Fig.1 Plan of a coral island(a)(based on Chenet al,2019)and computational model of the island(b)

表1 选取的物理力学参数<br/>Tab.1 Physical and mechanical parameters used in this study

表1 选取的物理力学参数
Tab.1 Physical and mechanical parameters used in this study

图2 输入KNG201(a),KNG202(b),KNG205(c)波时海底地震动加速度时程及Fourier幅值谱<br/>Fig.2 Acceleration time-histories and Fourier amplitudes when inputting waves spectrum of KNG201 seismogram(a),KNG202 seismogram(b),KNG205 seismogram(c)

图2 输入KNG201(a),KNG202(b),KNG205(c)波时海底地震动加速度时程及Fourier幅值谱
Fig.2 Acceleration time-histories and Fourier amplitudes when inputting waves spectrum of KNG201 seismogram(a),KNG202 seismogram(b),KNG205 seismogram(c)

图3 岛礁场地剖面<br/>Fig.3 Two-dimensional cross-section of the island

图3 岛礁场地剖面
Fig.3 Two-dimensional cross-section of the island

图4 输入KNG201(a),KNG202(b),KNG205(c)波时岛礁PGA放大系数分布<br/>Fig.4 Acceleration amplification factors of the island when inputting waves of KNG201 seismogram(a),KNG202 seismogram(b),KNG205 seismogram(c)

图4 输入KNG201(a),KNG202(b),KNG205(c)波时岛礁PGA放大系数分布
Fig.4 Acceleration amplification factors of the island when inputting waves of KNG201 seismogram(a),KNG202 seismogram(b),KNG205 seismogram(c)

图5 输入不同峰值的KNG205波时在A(a),B(b),C(c)3点PGA放大系数沿深度分布<br/>Fig.5 Acceleration amplification factors at A(a),B(b),C(c)points varying with soil depth when inputting waves of KNG205 seismogram with different peaks

图5 输入不同峰值的KNG205波时在A(a),B(b),C(c)3点PGA放大系数沿深度分布
Fig.5 Acceleration amplification factors at A(a),B(b),C(c)points varying with soil depth when inputting waves of KNG205 seismogram with different peaks

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备注

引言

1 珊瑚岛礁场地地震反应分析的模型及参数

2 海底地震动作用下岛礁场地反应特征分析

3 结论

期刊信息