砂土中单桩水平循环累积变形特性模型试验  

Model tests on cumulative deformation characteristics of a single pile subjected to lateral cyclic loading in sand

作　　者：张勋 黄茂松[2] 胡志平[1] ZHANG Xun;HUANG Mao-song;HU Zhi-ping(School of Civil Engineering,Chang'an University,Xi'an,Shaanxi 710061,China;Department of Geotechnical Engineering,Tongji University,Shanghai,200092,China)

机构地区：[1]长安大学建筑工程学院,陕西西安710061 [2]同济大学地下建筑与工程系,上海200092

出　　处：《岩土力学》2019年第3期933-941,共9页Rock and Soil Mechanics

基　　金：国家重点基础研究发展计划(973计划)(No.2013CB036304);中央高校基本科研业务费资助项目(No.310828171013)~~

摘　　要：针对典型的浅海风机大直径单桩基础,采用自主设计的水平循环加载装置,在砂土地基中完成了单桩模型试验,揭示了长期水平循环加载下单桩累积变形响应特征。试验结果表明,桩顶水平累积位移随循环次数的变化呈两阶段特征,循环加载短期效应大于长期效应;砂土密实度及循环加载路径对桩顶累积位移特征影响较大;不同初始条件下,单桩水平循环刚度随着循环次数的增大而不断增大;不同密实砂土中循环后单桩水平静承载力的变化与松密砂剪切硬软化机制不完全一致。基于经验公式法,对单桩水平循环累积位移预测模型进行了参数分析。与试验结果对比分析表明,该模型能较好地预测不同循环加载路径下单桩累积位移。Large-diameter single pile foundation is a typical foundation type for offshore wind turbines. Model tests of large-diameter single pile are conducted using a simple mechanical load rig designed in-house in sand. The cumulative deformation response of a single pile under long-term lateral cyclic loading is discussed. The test results indicate that the cumulative displacement of the pile head presents two phase characteristics with number of cycles, and the short-term effect for lateral cyclic loading is greater than the long-term effect. Sand density and cyclic loading paths greatly influence the displacement characteristics of the pile head. The lateral secant stiffness of the pile head increases with cycling under different initial conditions. The change of horizontal static bearing capacity of single pile after cyclic loading in sands of different densities is not completely consistent with hard-soft mechanism for loose-dense sand subjected to shear. The prediction model parameters for lateral cyclic cumulative displacement of single pile are obtained by use of the empirical formula method. Comparison between the calculation results and the test results show that this model can effectively predict the cumulative displacement of single pile under different cyclic paths.

关 键 词：单桩 砂土 水平循环加载 累积位移 预测模型 

分 类 号：TU472.32[建筑科学—结构工程]