张靖皋长江大桥锚碇基础软土夹层蠕变特性试验及分形蠕变模型研究  

Research on Creep Characteristics and Fractal Creep Model of Soft Soil Interlayer on Anchoring Foundation of Zhang-Jing-gao Yangtze River Bridge

作　　者：罗超[1] 郝海龙[1] 魏乐永[1] 龚维明[2] LUO Chao;HAO Hai-long;WEI Le-yong;GONG Wei-ming(CCCC Highway Consultants Co.Ltd.,Beijing 100010,China;Southeast University,Nanjing 210096,China)

机构地区：[1]中交公路规划设计院有限公司,北京市100010 [2]东南大学,南京市210096

出　　处：《公路》2023年第6期99-106,共8页Highway

基　　金：国家重点研发计划项目,项目编号2021YFB1600301;中国交通建设集团有限公司科技项目,项目编号2022-ZJKJ-01。

摘　　要：张靖皋长江大桥锚碇基础位于中国南方临江富水且软土夹层深厚地区。该层软土的蠕变特性对桥梁基础的变形稳定性有着重要的影响,不容忽视。利用GDS应力路径三轴试验系统,采用分别加载方式开展了一系列三轴固结排水剪切蠕变试验,研究了江苏临江软土的蠕变特性。试验结果表明,软土蠕变分为瞬时应变、衰减蠕变及稳定蠕变3个阶段,呈现出典型的非线性蠕变行为且随时间和应力增长表现出稳态蠕变的特征。通过拟合不同应力水平下的试验结果,基于分形导数理论,引入分形黏壶代替传统Abel黏壶,建立了适用于江苏临江地区软土的非线性分形Burgers蠕变模型。相比于传统模型,该分形Burgers模型参数少、精度高、物理意义明确。研究结果对于预测基础变形和制定控制基础变位的措施具有一定意义,可为中国南方沿江地区的工程应用提供参考。The anchoring foundation of Zhang-Jing-gao Yangtze River Bridge is located in a riverside area with rich water and deep interlayer of soft soil in southern China.The creep characteristics of the soft soil have an important influence on the deformation stability of the bridge foundation,which cannot be ignored.A series of triaxial consolidation drainage shear creep tests are carried out by using the GDS stress path triaxial test system with separate loading methods to study the creep characteristics of Jiangsu riverside soft soil.The test results show that the creep of soft soil is divided into three stages:instantaneous strain,attenuation creep and stable creep,showing typical nonlinear creep behavior and steady-state creep and shear shrinkage with the increase of time and stress.By fitting the test results under different stress levels and based on the fractal derivative theory,a nonlinear fractal Burgers creep model suitable for soft soil in Jiangsu is established by introducing the fractal dashpot instead of the traditional Abel dashpot.Compared with traditional model,the four-component fractal Burgers model has fewer parameters,higher precision and clear physical meaning.The sensitivity analyses of model parameters further reveal the influence of key parameters on soil creep characteristics,and confirm the effectiveness of the proposed model in describing the creep behavior of soft soil.These observations are extremely important for predicting the foundation displacement and formulating measures to prevent the deformation,which can provide reference for practice applications in the riverside area of southern China.

关 键 词：锚碇基础 软土地基 三轴固结排水试验 蠕变特性 分形Burgers模型 

分 类 号：U443.24[建筑科学—桥梁与隧道工程] U448.25[交通运输工程—道路与铁道工程]