考虑黏性的液化土中水平振动桩基桩顶阻抗研究  

Analytical solution to lateral dynamic impedance of piles in viscous liquefied soil

作　　者：黄娟[1] 胡钟伟 余俊[1] 李东凯 HUANG Juan;HU Zhong-wei;YU Jun;LI Dong-kai(School of Civil Engineering,Central South University,Changsha,Hunan 410075,China)

机构地区：[1]中南大学土木工程学院,湖南长沙410075

出　　处：《岩土力学》2023年第5期1445-1456,共12页Rock and Soil Mechanics

基　　金：国家自然科学基金资助项目(No.51008311)。

摘　　要：建立了三维黏性流体-桩-土体相互作用分析模型,对简谐激振水平动荷载作用下的液化土中桩基振动响应问题进行解析研究。将桩周液化土体视为黏性不可压缩流体,建立流体运动方程,利用亥姆霍兹分解和分离变量法并结合流体边界条件和桩-流体位移、速度连续条件及桩身边界条件,求得了黏性流体动压力及流体速度势解析表达式,从而得到桩身阻力表达式。用饱和多孔介质模型模拟饱和未液化土层,在已有饱和未液化土层振动响应解析解的基础上,推导得出上覆黏性液化流体,下层土体为饱和未液化土中水平振动桩基桩顶阻抗解析解。与已有的水中悬臂梁自由振动解析解对比,验证提出的模型解的正确性,最后分析了流体黏滞系数、桩长、桩土模量比对桩顶阻抗的影响。结果表明,忽略液化土体的黏性特征会高估桩基础桩顶的刚度阻抗,低估其阻尼阻抗。A three-dimensional viscous fluid-pile-soil interaction analysis model is established to analyze the vibration response of pile foundation in liquefied soil under simple harmonic excitation horizontal dynamic load.The liquefied soil around the pile is regarded as viscous incompressible fluid,and the fluid motion equation is established.The analytical expressions of viscous fluid dynamic pressure and fluid velocity potential are obtained by using Helmholtz decomposition and variable separation method,combining fluid boundary conditions,pile-fluid displacement,velocity continuity conditions and pile boundary conditions,so as to obtain the expression of pile resistance.The saturated unliquefied soil layer is simulated using the saturated porous medium model.Based on the existing analytical solution of vibration response of saturated unliquefied soil layer,the analytical solution of pile top impedance of horizontal vibrating pile foundation in saturated unliquefied soil is derived.The correctness of the solution of the proposed model is verified by comparing with the free vibration solution of the existing cantilever beam in water.Finally,the effects of fluid viscosity coefficient,pile length and pile-soil modulus ratio on pile top impedance are analyzed.The results show that neglecting the viscosity characteristics of liquefied soil will overestimate the stiffness and impedance of pile foundation and underestimate the damping impedance.

关 键 词：液化土 黏性流体 水平振动 桩基 桩顶阻抗 

分 类 号：TU473[建筑科学—结构工程]