地震作用下的液化砂土地基PHC管桩动态响应

为研究液化砂土地基上的PHC管桩在地震作用下的动态响应,利用FLAC3D有限差分软件建立土体、实体PHC管桩和桩顶等效质体组成的数值模型,同时考虑水体、土体和PHC管桩之间的耦合作用。通过在模型底部施加地震荷载进行完全非线性动力分析,研究土体的液化情况、场地的变形以及PHC管桩的响应。结果表明,地震作用引起了饱和砂土有效应力减小,全高度的砂土均发生了液化;液化的发生与否以及发生时间不仅与土体的埋深有关,也与地震荷载的序列和地震荷载的峰值加速度相关;埋入土中的桩身正应力呈先增大再减小的趋势,最大值出现在护坡和砂土交界处;埋深较浅处桩的侧向位移大于埋深较深处;由于PHC管桩在强震作用下的位移和内力值均较大,应在码头建造之前对极易液化的场地进行改善。

Dynamic response of PHC pipe pile in liquefied sandy soil foundation under earthquake

In order to study the dynamic response of PHC pipe piles on the liquefied sandy soil foundation under earthquake,we apply FLAC3D finite difference software to establish soil,solid PHC pipe pile and equivalent mass at pile top as superstructure considering the coupling among the water body,the soil and the PHC pipe pile,and study the liquefaction of the soil,the deformation of the site and the response of the PHC pipe pile by the application of seismic loads at the bottom of the model for complete nonlinear dynamic analysis.The results show that the effective stress of saturated sand decreases due to seismic action,and liquefaction occurs in all height of sand.The occurrence and time of liquefaction are not only related to the buried depth of soil,but also to the sequence of seismic loads and the peak acceleration of seismic loads.The normal stress of pile embedded in soil increases first and then decreases,and the maximum value appears at the junction of slope protection and sandy soil.The lateral displacement of pile in shallow depth is larger than that in deep depth.The displacement and internal force of PHC pipe piles under strong earthquake are both large,and it is necessary to improve the liquefaction site before the construction of the wharf.