分数阶黏弹性饱和地基中大直径管桩竖向动力响应分析  

Vertical dynamic response analysis of large diameter piles in fractional viscoelastic saturated foundation

作　　者：周凤玺[1] 孙烈璞 柳鸿博 曹小林[1] 梁玉旺 ZHOU Feng-xi;SUN Lie-pu;LIU Hong-bo;CAO Xiao-lin;LIANG Yu-wang(School of Civil Engineering,Lanzhou University of Technology,Lanzhou,Gansu 730050,China;School of Civil Engineering,Southeast University,Nanjing,Jiangsu 211189,China)

机构地区：[1]兰州理工大学土木工程学院,甘肃兰州730050 [2]东南大学土木工程学院,江苏南京211189

出　　处：《岩土力学》2024年第11期3481-3490,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.12362032);甘肃省重点研发计划(No.23YFFA0063)。

摘　　要：管桩作为一种常用的桩基础,在实际工程中被广泛应用,其动力响应分析具有重要研究价值。基于弹性动力学原理和黏弹性饱和土模型,考虑了土骨架的非流动黏性和管桩的横向惯性效应,研究了分数阶黏弹性饱和土中大直径管桩在竖向动载荷作用下的动力特性。首先,基于Biot动力固结理论和分数阶标准线性固体(fractional-order standard linear solid,简称FSLS)模型,建立了分数阶黏弹性饱和土在柱坐标系下的波动方程。其次,基于Rayleigh-Love杆模型并考虑管桩的横向惯性效应,推导了管桩的桩顶动阻抗解析解答。最后,通过算例分析,研究了分数阶模型参数、管桩横向惯性效应、桩长和土体渗透力对管桩桩顶动阻抗的影响规律。结果表明:饱和土体骨架FSLS模型参数中分数阶数和应变松弛时间的增大以及应力松弛时间的减小都会增大桩顶动阻抗;管桩的横向惯性效应在高频区段对降低桩顶动阻抗尤为明显;缩小管桩外半径和扩大其内半径以及增加桩长,降低土体渗透性均有助于提高桩顶动阻抗。As a commonly used pile foundation,tubular piles are widely used in practical engineering,and their dynamic response analysis has important research value.Based on the principle of elastic dynamics and viscoelastic saturated soil model,the dynamic characteristics of large-diameter tubular piles in fractional-order viscoelastic saturated soil under vertical dynamic load are investigated by taking into account the immobile viscosity of the soil skeleton and the lateral inertia effect of the tubular piles.Firstly,the fluctuation equations of fractional-order viscoelastic saturated soil in column coordinate system were established based on Biot's dynamic consolidation theory and fractional-order standard linear solid(FSLS)model.Secondly,based on the Rayleigh-Love rod model and considering the lateral inertia effect of the tubular piles,the analytical solution of the pile top dynamic impedance of the tubular piles is derived.Finally,the effects of fractional order model parameters,lateral inertia effect of tubular piles,pile length and soil permeability on the dynamic impedance of pile top of tubular piles are investigated by example analysis.The results show that:the increase of fractional order and strain relaxation time and the decrease of stress relaxation time in the FSLS model parameters of saturated soil skeleton increase the dynamic impedance at the top of the pile;the transverse inertia effect of tubular piles is especially obvious in the high-frequency section to reduce the dynamic impedance at the top of the pile;and the reduction of the outer radius of tubular piles and enlargement of the inner radius of tubular piles,as well as the increase of the pile length and decrease of the permeability of the soil body all help to improve the dynamic impedance at the top of the pile.

关 键 词：管桩 饱和土 分数阶黏弹性 横向惯性效应 动阻抗 

分 类 号：TU473[建筑科学—结构工程]