嵌岩特性对嵌岩桩桩顶纵向振动阻抗的影响研究

摘要

基于平面应变模型和Rayleigh-Love杆模型，建立了成层地基中嵌岩桩纵向振动的计算模型和控制方程，结合边界条件和初始条件，采用Laplace变换技术和阻抗函数递推技术求得了任意荷载作用下嵌岩桩桩顶纵向振动复阻抗的频域解析解，并在桩基础动力设计关注的低频范围内详细讨论了嵌岩特性对嵌岩桩桩顶纵向振动阻抗的影响。结果表明：对于同一上覆土层，动刚度随着嵌岩深度的增大而减小，而动阻尼则逐渐增大；对于嵌岩桩段半径等于桩半径的嵌岩桩，动刚度和动阻尼均随着桩身截面半径的增大而增大，对于嵌岩桩段半径小于桩半径的嵌岩桩，随着嵌岩桩段半径的减小，动刚度逐渐减小，动阻尼逐渐增大；随着岩层特性变好，动刚度逐渐增大，动阻尼逐渐减小。%Based on the plane strain model and Reyleigh-Love rod model,the calculating model and governing equation of a rock-socketed pile embedded in layered soil was established during an arbitrary vertical exciting force acting on the pile head.Combining the boundary conditions and initial conditions,the analytical solution to vertical dynamic impedance at the head of the rock-socketed pile was derived by means of Laplace transformation and the impedance function transfer method.By means of parametric study method,the influence of rock-socketed characteristics on the vertical dynamic impedance at the head of the rock-socketed pile was investigated within a lower frequency range.The results showed that for a certain depth of overlaying soil,the dynamic stiffness decreases with increase in the rock-socketed length while the dynamic damping increases with increase in rock-socketed length;when the radius of rock-socketed segment is equal to pile radius the dynamic stiffness and dynamic damping increase with increase in pile radius;when the radius of rock-socketed segment is less than pile radius,the dynamic stiffness decreases with decrease in radius of rock-socketed segment,but the dynamic damping increases with decrease in radius of rock-socketed segment;the dynamic stiffness increases and the dynamic damping decreases with increase in shear wave velocity of bedrock.