基于混合波场地震动输入技术的近海场地地震反应分析方法  

Seismic response analysis method of offshore site based on the seismic wave input technique of hybrid wave field

作　　者：宝鑫[1] 刘晶波[1] 李述涛 王菲 Bao Xin;Liu Jingbo;Li Shutao;Wang Fei(Department of Civil Engineering,Tsinghua University,Beijing 100084,China;National Defense Engineering Research Institute,Academy of Military Science,Beijing 100036,China)

机构地区：[1]清华大学土木工程系,北京100084 [2]军事科学院国防工程研究院,北京100036

出　　处：《地震学报》2022年第1期5-14,共10页Acta Seismologica Sinica

基　　金：国家自然科学基金(52108458,51878384);博士后创新人才支持计划(BX20200192);国家重点研发计划(2018YFC1504305);清华大学“水木学者”计划(2020SM005)共同资助。

摘　　要：基于人工边界子结构模型,提出一种利用混合波场实现近海场地中地震P波和SV波垂直输入的方法.该方法中用于波动输入的混合波场由计算模型两侧截断边界的自由波场和底面边界的入射波场构成,避免了不规则近海场地的自由波场求解.同时采用基于声流体单元的流固耦合算法模拟场地-海水动力相互作用,利用流体介质人工边界和黏弹性人工边界单元模拟无限流、固介质的辐射阻尼,建立了近海场地动力相互作用分析模型.将该模型与基于混合波场的地震波动输入方法相结合,提出了近海场地地震反应时域整体分析方法.数值算例表明,本文的计算模型和分析方法可以较为准确地实现地震波在近海场地中的输入问题,对于近海场地及海洋工程的地震反应分析具有良好的适用性.The seismic response analysis of offshore site is the foundation for the seismic safety evaluation of ocean engineering. Seismic wave input is a key part of site seismic response analysis. However,the slope of the offshore site inclines to the ocean,which interacts with the seawater directly,leading to natural difficulties in solving the free wave field and thus provides a challenge to the existing seismic wave input methods based on the free wave fields. In this study,we adopted and improved the seismic wave input method based on the substructure of artificial boundaries,and constructed a hybrid input wave field with the free wave field on two lateral boundaries and the incident wave field on the bottom boundary of the calculation model.On that basis,an offshore site seismic wave input method for vertically incident P and SV waves is proposed. The proposed method avoids calculating the free wave field of irregular offshore sites,therefore it can simplify the seismic response analysis of offshore engineering considering characteristics of offshore site and the soil-structure interaction. Meanwhile,the fluidstructure coupling algorithm based on the acoustic fluid element is used to simulate the dynamic interaction between the offshore site and the seawater,and the fluid dynamic artificial boundary and the uniform viscoelastic artificial boundary element are used to simulate the radiation damping of the infinite fluid and solid medium. On that basis,the dynamic interaction model of offshore site is established. Combine this model with the proposed seismic wave input method based on the hybrid wave field,thereby an overall time-domain analysis method for the seismic response of offshore sites is established. Numerical examples show that the analysis method and numerical model proposed in this study can accurately realize the input of seismic waves in offshore sites,and have good applicability for seismic response analysis of offshore engineering.

关 键 词：近海场地 地震波动输入 地震动场 人工边界 流固耦合 

分 类 号：P315.9[天文地球—地震学] TB123[天文地球—固体地球物理学]