基于非局部理论的土中桩基纵向振动特性分析  

Analysis of longitudinal vibration characteristics of pile foundation based on nonlocal theory

作　　者：余春春 傅敏[1] YU Chunchun;FU Min(College of Civil Engineering and Architecture,Zhejiang College of Construction,Hangzhou 311200,China)

机构地区：[1]浙江建设职业技术学院建筑工程学院,浙江杭州311200

出　　处：《四川建筑科学研究》2023年第3期74-79,97,共7页Sichuan Building Science

摘　　要：为了考虑土体孔隙动应力、孔隙尺度和土体颗粒大小等因素的影响,在Eringen提出的非局部理论的基础上,结合土动力学理论,建立了基于非局部理论的土体振动控制方程。将桩-土之间的动力相互作用等效为动力Winkler弹簧-阻尼器,忽略桩周土体的径向位移和环向位移,运用Novak薄层法,考虑土体无穷远处和桩-土接触面处的边界条件,得到了桩周土体纵向振动的解析解以及动力Winkler弹簧-阻尼器的刚度系数和阻尼系数。在基于非局部理论土体纵向振动研究的基础上,建立了桩基的纵向振动控制方程,根据桩端边界条件求解了桩基的纵向振动问题,给出了桩顶复刚度和导纳的解析解。通过数值算例分析了非局部效应、桩基长径比和桩土模量比对考虑非局部效应的土中桩基纵向振动的影响规律。数值分析结果表明:简谐荷载作用下,考虑非局部效应的桩-土系统同样存在共振现象;在高频时,非局部效应对桩基纵向振动的影响不能忽略;桩土长径比和桩土模量比的影响较大,桩基几何尺寸是桩基抗震设计需要重点关注的因素,可以通过改变桩身混凝土弹性模量或者对土体进行夯实等措施来改善桩基的振动。In order to consider the effects of soil pore dynamic stress,pore size and soil particle size,a soil vibration control equation was established based on nonlocal theory proposed by Eringen and combined with soil dynamic theory.The dynamic interaction between pile and soil was equivalent to dynamic Winkler spring-damper,and ignored the radial displacement and circumferential displacement of the soil around the pile.The analytical solution of the longitudinal vibration of the soil around the pile and the stiffness coefficient and damping coefficient of the dynamic Winkler spring-damper were obtained by using the Novak thin layer method and considering the boundary conditions at the infinity of the soil and the pile-soil contact surface.Based on the study of longitudinal vibration of soil based on nonlocal theory,the longitudinal dynamic control equation of pile foundation was established,the longitudinal dynamic problem of pile foundation was solved according to the boundary conditions at the pile end,and the analytical solutions of complex stiffness and admittance at the pile top were given.Through numerical examples,the effects of nonlocal effect,pile length-diameter ratio and pile-soil modulus ratio on the longitudinal vibration of pile foundation in soil based on nonlocal theory were investigated.The numerical results show that the pile-soil system considering nonlocal effect also has resonance under simple harmonic load.At high frequency,the influence of nonlocal effect on the longitudinal vibration of pile foundation can not be ignored.The influences of pile-soil lengthdiameter ratio and pile-soil modulus ratio are greater.The geometric size of pile foundation is a key factor in the seismic design of pile foundation.The vibration of pile foundation can be improved by changing the elastic modulus of pile concrete or tamping the soil and so on.

关 键 词：非局部理论 Novak薄层法 纵向振动 桩顶复刚度 长径比 

分 类 号：TU473.12[建筑科学—结构工程]