动水压力对深水桥梁单桩地震响应的影响研究  

Study on the effects of hydrodynamic pressure on the seismic responses of monopile embedded in deep water

作　　者：李芬[1] 彭晓宇 黄蔚源 胡丹[1] LI Fen;PENG Xiaoyu;HUANG Weiyuan;HU Dan(School of Naval Architecture,Ocean and Energy Power Engineering,Wuhan University of Technology,Wuhan 430063,China;Hubei Provincial Communications Planning&Design Institute Co.,Ltd.,Wuhan 430000,China)

机构地区：[1]武汉理工大学船海能动学院,湖北武汉430063 [2]湖北省交通规划设计院股份有限公司,湖北武汉430000

出　　处：《地震工程与工程振动》2022年第4期70-79,共10页Earthquake Engineering and Engineering Dynamics

基　　金：国家自然科学基金项目(51808421);中央高校基本科研业务费专项资助项目(2021IVA009)。

摘　　要：在深水环境下,流体-桥梁桩基的动力相互作用会对桩基水下部分产生动水压力,同时在地震、波流等循环荷载作用下海床的土体特性发生变化,进而对桩基的抗震性能产生影响,因此有必要对流体-桩基-海床的动力相互作用展开全面而深入的研究。文中基于饱和软黏土刚度衰减模型,建立了考虑地震动水效应的桩基-海床数值模型,探讨在不同地震动输入下,地震动水压力对桩基位移、剪力、弯矩反应的影响。研究表明:动水压力对桩基动力响应的影响程度与输入的地震动特性有关,一般在频率较低(如f=1~5 Hz)、烈度较大的地震激励下,动水压力的影响更为显著。考虑动水压力时,桩基出水面部分的位移增大,埋置在土层内的桩身剪力增大,桩底负弯矩增大,且从出现响应峰值时刻开始,动水压力对桩基位移、剪力、弯矩时程反应的影响更为明显。因此,在开展深海桥梁桩基设计时,有必要考虑地震动水效应对桩基抗震性能的影响。文中还进一步讨论了考虑动水压力时,桩基入水深度、土层厚度和地震烈度等因素对桩基动力响应的影响,结果表明随着水深增加、地震烈度变大,动水压力对桩基弯矩响应的影响更为显著;随着土层厚度的增加,动水压力对桩基位移的影响更为明显,该研究为深水桥梁桩基的抗震设计提供了重要的参考依据。Under deep water environment,the hydrodynamic pressure induced by the water-pile interaction is acted on the monopile.On the other hand,the cyclic loading such as the seismic and wave-current loads contribute to the stiffness degradation of soil,thus further affect the seismic performance of monopile.Therefore,it is necessary to conduct the comprehensive study on the water-pile-seabed interaction mechanism.In this study,based on the proposed stiffness degradation model of saturated soft clay,the seabed-pile interaction model was established to investigate the effect of seismic hydrodynamic pressure on the dynamic response of monopile under different seismic input motions.It is investigated that the effect of hydrodynamic pressure is largely dependent on the seismic characteristics.Specifically,under the earthquake excitation with low frequency(f=1~5 Hz)and large intensity,the seismic hydrodynamic pressure amplifies the response of monopile more significantly.The seismic hydrodynamic pressure induces larger positive displacement along the pile above water,the shear stress along the pile embedded in seabed increases,as well as larger bending moment at pile bottom.Moreover,the effect of hydrodynamic pressure on the time history responses of monopile becomes more significant as the peak amplitude appears.Furthermore,the effect of water depth,seabed depth and seismic intensity on the dynamic responses of monopile have been discussed.With the increase of water depth and seismic intensity,the effect of hydrodynamic pressure is much more obvious,especially on the pile bending moment,whereas the displacement increases more significantly with deeper seabed depth,which can be served as a critical reference for the seismic design of monopile embedded in deep water.

关 键 词：桥梁工程 单桩-海床相互作用 桩基动力响应分析 动水压力 地震响应 饱和多孔介质 刚度衰减模型 

分 类 号：U442.39[建筑科学—桥梁与隧道工程]