基于PIV技术与分形理论的桩-土系统水平循环受荷模型试验研究  

Experimental study on lateral cyclic loading model of pile-soil system based on PIV technique and fractal theory

作　　者：袁炳祥[1] 李志杰 陈伟杰 罗庆姿 杨光华[2] 王永洪[3] YUAN Bingxiang;LI Zhijie;CHEN Weijie;LUO Qingzi;YANG Guanghua;WANG Yonghong(School of Civil and Transportation Engineering,Guangdong University of Technology,Guangzhou,Guangdong 510006,China;Guangdong Research Institute of Water Resources and Hydropower,Guangzhou,Guangdong 510610,China;School of Civil Engineering,Qingdao University of Technology,Qingdao,Shandong 266033,China)

机构地区：[1]广东工业大学土木与交通工程学院,广东广州510006 [2]广东省水利水电科学研究院,广东广州510610 [3]青岛理工大学土木工程学院,山东青岛266033

出　　处：《岩石力学与工程学报》2023年第2期466-482,共17页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51978177,52278336,41902288)。

摘　　要：单桩基础作为涡轮风机常用的基础形式之一,常受周期性横向荷载的作用,这将导致桩-土系统动力响应的变化。通过改变土体相对密实度与粒径大小2个参量开展一系列室内模型试验,探究水平循环荷载作用下单桩基础的内力变化及累积变形特性,并利用PIV技术及分形理论分析桩周土体周期性的运动规律。试验结果表明:(1)循环荷载对于桩身弯矩的影响较为显著,随着循环次数的增大,桩身弯矩值随之减小,减小的幅度随土体相对密实度的增加而增大;同时,桩周土体粒径越小,桩身产生的弯矩相对较大。(2)桩基整体绕桩身一点做刚性转动,土体的相对密实度越高,桩身累积变形越小;砂-钢接触面的界面摩擦角受到土体粒径的影响,土体粒径越大,界面摩擦角越小,桩身的水平累积位移越大。(3)表层土体位移范围随土体相对密实度的增加而减小,而粒径大小对于土体位移场的影响较小;随着加载的进行,桩后土体位移影响范围增加,而桩前土体影响位移范围减小,桩周沿加载方向的部分土体会发生对流运动。(4)桩周土体位移场具有分形特征,分形维数值随着土体相对密实度的增加而减小,大小在1.18~1.42范围;分形维数与土体位移场面积之间呈现正比例线性关系,而与循环次数之间呈现指数函数关系;以此提出了拟合公式,与已有数据点的拟合结果较好。该研究结果可为探究水平循环荷载作用下桩-土系统的稳定性评估提供试验基础。As one of the common forms of foundations for the wind turbine,monopile is often subjected to cyclic lateral loading,which can lead to changes in the dynamic response of the pile-soil system.In order to investigate the internal force variation and the cumulative deformation characteristics of the monopile,a series of model tests were carried out by varying two parameters:the relative density and the particle size of the soil.And the movement law of the soil around the pile under cyclic loading was analysed by the PIV technique and fractal theory.The test results showed that:(1)The influence of cyclic loading on the bending moment of the pile was relatively significant.With the increase of the number of cycles,the magnitude of the bending moment reduced,and the amplitude rose with the increase of the relative density of the soil.In addition,the smaller the particle size of the soil around the pile,the larger the bending moment.(2)The monopile rotated rigidly around a point.The amount of cumulative deformation of the pile decreased with the increase in the relative density.The interfacial friction angle of the sandsteel contact surface was affected by the particle size of the soil.The larger the particle size,the smaller the interfacial friction angle and the larger the lateral cumulative displacement of the pile.(3)The displacement range of the surface soil decreased with the increase in the relative density of the soil,and the particle size had less influence on the displacement field.As the loading progressed,the displacement range of the soil behind the pile increased,while the displacement range of the soil in front of the pile decreased,and convective movement occurred in part of the soil along the loading direction.(4)The displacement field of the soil around the pile exhibited fractal characteristics,and the fractal dimension value decreased with the increase in the relative density of the soil,varying between 1.18 and 1.42.The fractal dimension showed a positive linear relationship with the area of the soi

关 键 词：桩基础 循环荷载 桩-土相互作用 PIV技术 分形理论 模型试验 

分 类 号：TU473[建筑科学—结构工程]