考虑动载作用冻土桩基传递函数及其影响系数研究  

Study on Transfer Function and Influence Coefficient of Pile Foundation in Frozen Soil Considering Dynamic Loading

作　　者：张召阳 吴亚平[2] 杜兆金 陈林海 蒋硕 ZHANG Zhaoyang;WU Yaping;DU Zhaojin;CHEN Linhai;JIANG Shuo(Jiangsu Testing Center for Quality of construction engineering Co.,Ltd.,Nanjing 210028,China;School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;School of Civil Engineering,Central South University,Changsha,410075,China)

机构地区：[1]江苏省建筑工程质量检测中心有限公司,南京210028 [2]兰州交通大学土木工程学院,兰州730070 [3]中南大学土木工程学院,长沙410075

出　　处：《铁道标准设计》2020年第11期44-50,共7页Railway Standard Design

基　　金：国家科技支撑计划项目(2014BAG05B05)。

摘　　要：为了研究动载对冻土桩基传递函数的影响,制作了室内冻土-混凝土单桩模型,在静载的基础上对模型桩施加不同频率和不同大小的正弦波动荷载,分析冻土桩基的桩土相对位移、桩身轴力以及桩侧冻结应力沿桩体埋深的变化规律,并根据试验结果进行理论推导,得出考虑动荷载作用的冻土桩基传递函数及反映动载影响的动荷载系数。结果表明:桩土相对位移与桩身轴力沿桩体埋深逐渐减小,桩土相对位移沿埋深近似呈1/4正弦波长变化,桩侧冻结应力沿桩体埋深先增大后减小,在桩体埋深1/2处达到最大值;随着动载频率的增大,桩顶位移、桩土相对位移及轴力减小而桩侧冻结应力增大;桩侧冻结应力沿桩体埋深的传递函数可表示为桩土相对位移与动载频率的函数,据此得到动载影响系数沿埋深的变化,其大小随着动载频率及动载占比的增大而增大。In order to study the influence of dynamic load on the transfer function of pile foundation in frozen soil,a single pile model of indoor permafrost-concrete is established and sinusoidal wave loads of different frequencies and magnitude are applied to the model pile on the basis of static load to analyze the relative displacement of soil,axial force and frozen stress along the buried depth of permafrost pile foundation.The transfer function of permafrost pile foundation under dynamic load and the dynamic load coefficient reflecting dynamic load influences are obtained based on theoretical deduction of the test results.The results show that the relative displacement of pile-soil and the axial force of pile gradually decrease with the depth of the pile in the soil,the relative displacement of pile-soil is approximately 1/4 sine wave length along the buried depth,the frozen stress at pile side increases first and then decreases along the buried depth of pile,and maximizes at 1/2 of the buried depth of the pile;with the increase of the dynamic frequency,pile top displacement and relative displacement of pile and soil and axial force decrease while pile side freezing stress increases;the transfer function of frozen stress along the buried depth of pile can be expressed as the function of relative displacement and dynamic load frequency of pile and soil;accordingly,the variation of dynamic load influence coefficient along the buried depth is obtained,and its magnitude increases with the increase of dynamic load frequency and dynamic load proportion.

关 键 词：冻土 混凝土模型桩 动荷载 桩土相对位移 传递函数 动载影响系数 

分 类 号：TU752[建筑科学—建筑技术科学] U416.1[交通运输工程—道路与铁道工程]