Influence of thick soft superficial layers of seabed on ground motion and its treatment suggestions for site response analysis

The thick soft superficial layers of the seabed greatly influence ground motion generally. It is worth studying how to find out the influence of these soft layers on ground motion parameters and determine reasonable seismic fortification parameters for ocean engineering. Numerical experiments of sit...

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Autores principales:	Jiang Qifeng, Rong Mianshui, Wei Wei, Zhang Bin, Wang Jixin
Formato:	article
Lenguaje:	EN
Publicado:	De Gruyter 2021
Materias:	offshore site thick soft superficial layer site response analysis peak ground acceleration characteristic period response spectrum Geology QE1-996.5
Acceso en línea:	https://doaj.org/article/f90dd9ef5ddb4a7e9878e6ac87a9b192
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id	oai:doaj.org-article:f90dd9ef5ddb4a7e9878e6ac87a9b192
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spelling	oai:doaj.org-article:f90dd9ef5ddb4a7e9878e6ac87a9b1922021-12-05T14:10:49ZInfluence of thick soft superficial layers of seabed on ground motion and its treatment suggestions for site response analysis2391-544710.1515/geo-2020-0302https://doaj.org/article/f90dd9ef5ddb4a7e9878e6ac87a9b1922021-10-01T00:00:00Zhttps://doi.org/10.1515/geo-2020-0302https://doaj.org/toc/2391-5447The thick soft superficial layers of the seabed greatly influence ground motion generally. It is worth studying how to find out the influence of these soft layers on ground motion parameters and determine reasonable seismic fortification parameters for ocean engineering. Numerical experiments of site response analysis are designed using two offshore engineering sites in this study. First, the borehole profiles are selected and stripped layer by layer to generate new profiles. Second, 108 acceleration time histories are synthesized which basically represent the diversity of input motions’ amplitude and frequency. Third, a method that can automatically calculate characteristic periods and normalize response spectra is created to improve calculation efficiency. Fourth, peak accelerations, response spectra, and characteristic periods at different depths of the profiles with different stripping depths are calculated. The results show that the thick soft superficial layers can significantly decrease peak ground accelerations and increase characteristic periods, resulting in serious “low-fat” response spectra. The situation can be greatly improved by stripping off the soft superficial layers. After stripping off the thick soft superficial silt layers, if stripping is continued further, the variation in the superficial amplification ratios of peak accelerations and superficial characteristic periods will no longer be drastic, and the superficial amplification ratios and characteristic periods both tend to be mostly the same. The relative deviation of the amplification ratio of peak ground acceleration between a profile stripped and that without stripping can be 143%, and it can be 83% for characteristic period. It is advisable to strip off thick soft superficial layers to perform site response analysis, and the shear force at the bottom of the silt should be considered in engineering based on local seismic activity level, and the silt’s and the structure’s physical parameters.Jiang QifengRong MianshuiWei WeiZhang BinWang JixinDe Gruyterarticleoffshore sitethick soft superficial layersite response analysispeak ground accelerationcharacteristic periodresponse spectrumGeologyQE1-996.5ENOpen Geosciences, Vol 13, Iss 1, Pp 1273-1289 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	offshore site thick soft superficial layer site response analysis peak ground acceleration characteristic period response spectrum Geology QE1-996.5
spellingShingle	offshore site thick soft superficial layer site response analysis peak ground acceleration characteristic period response spectrum Geology QE1-996.5 Jiang Qifeng Rong Mianshui Wei Wei Zhang Bin Wang Jixin Influence of thick soft superficial layers of seabed on ground motion and its treatment suggestions for site response analysis
description	The thick soft superficial layers of the seabed greatly influence ground motion generally. It is worth studying how to find out the influence of these soft layers on ground motion parameters and determine reasonable seismic fortification parameters for ocean engineering. Numerical experiments of site response analysis are designed using two offshore engineering sites in this study. First, the borehole profiles are selected and stripped layer by layer to generate new profiles. Second, 108 acceleration time histories are synthesized which basically represent the diversity of input motions’ amplitude and frequency. Third, a method that can automatically calculate characteristic periods and normalize response spectra is created to improve calculation efficiency. Fourth, peak accelerations, response spectra, and characteristic periods at different depths of the profiles with different stripping depths are calculated. The results show that the thick soft superficial layers can significantly decrease peak ground accelerations and increase characteristic periods, resulting in serious “low-fat” response spectra. The situation can be greatly improved by stripping off the soft superficial layers. After stripping off the thick soft superficial silt layers, if stripping is continued further, the variation in the superficial amplification ratios of peak accelerations and superficial characteristic periods will no longer be drastic, and the superficial amplification ratios and characteristic periods both tend to be mostly the same. The relative deviation of the amplification ratio of peak ground acceleration between a profile stripped and that without stripping can be 143%, and it can be 83% for characteristic period. It is advisable to strip off thick soft superficial layers to perform site response analysis, and the shear force at the bottom of the silt should be considered in engineering based on local seismic activity level, and the silt’s and the structure’s physical parameters.
format	article
author	Jiang Qifeng Rong Mianshui Wei Wei Zhang Bin Wang Jixin
author_facet	Jiang Qifeng Rong Mianshui Wei Wei Zhang Bin Wang Jixin
author_sort	Jiang Qifeng
title	Influence of thick soft superficial layers of seabed on ground motion and its treatment suggestions for site response analysis
title_short	Influence of thick soft superficial layers of seabed on ground motion and its treatment suggestions for site response analysis
title_full	Influence of thick soft superficial layers of seabed on ground motion and its treatment suggestions for site response analysis
title_fullStr	Influence of thick soft superficial layers of seabed on ground motion and its treatment suggestions for site response analysis
title_full_unstemmed	Influence of thick soft superficial layers of seabed on ground motion and its treatment suggestions for site response analysis
title_sort	influence of thick soft superficial layers of seabed on ground motion and its treatment suggestions for site response analysis
publisher	De Gruyter
publishDate	2021
url	https://doaj.org/article/f90dd9ef5ddb4a7e9878e6ac87a9b192
work_keys_str_mv	AT jiangqifeng influenceofthicksoftsuperficiallayersofseabedongroundmotionanditstreatmentsuggestionsforsiteresponseanalysis AT rongmianshui influenceofthicksoftsuperficiallayersofseabedongroundmotionanditstreatmentsuggestionsforsiteresponseanalysis AT weiwei influenceofthicksoftsuperficiallayersofseabedongroundmotionanditstreatmentsuggestionsforsiteresponseanalysis AT zhangbin influenceofthicksoftsuperficiallayersofseabedongroundmotionanditstreatmentsuggestionsforsiteresponseanalysis AT wangjixin influenceofthicksoftsuperficiallayersofseabedongroundmotionanditstreatmentsuggestionsforsiteresponseanalysis
_version_	1718371697230348288

Influence of thick soft superficial layers of seabed on ground motion and its treatment suggestions for site response analysis

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