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Date of Publication:2022-10-04

Journal:地震工程学报

Issue:2

Page Number:403-409

ISSN No.:1000-0844

Abstract:Re-liquefaction induced by aftershocks causes serious hazards on soil structures after the end of the main shock.In this study,the influences of aftershocks on an artificial island are discussed based on the FE-FD coupling finite element analysis method at different scales of after-shocks and interval time between the main shock and aftershock.The results indicate that with dissipation of excess pore-water pressure after the main shock,liquefied areas in the sand layer of the artificial island gradually decrease;however,the liquefied areas expand rapidly when an after-shock occurs,and can possibly be larger than the liquefied areas induced by the main shock;the extent of damage to the artificial island is much worse when an aftershock occurs than when it does not.The increasing of the interval time between the main shock and aftershock results in the drainage consolidation during this time significantly improving the ability of the artificial island to re-liquefy;thus,full-scale re-liquefaction in the artificial island is difficult when the excess pore-water pressure entirely dissipates.Settlement and horizontal displacement of the artificial island increases with increase of the peak acceleration of the aftershock and the liquefaction point-in-time of the sand layer occurs a few seconds early.After the main shock,with drainage by consolidation in the soil,settlement of the artificial island continues to increase,and is even larger than the set-tlement induced by the main shock,but the horizontal displacement barely changes.Before the af-tershock,if the sand layer of the artificial island is still liquefiable,the sand layer may play a role in seismic insulation and reduce the hazards caused by the aftershock to the artificial island.There-fore,it is necessary to consider multiple seismic fortifications during a period of time for offshore structures,especially for artificial islands.

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