夏季工况下扩底能量桩单桩热力学响应分析  

Thermomechanical Characteristics of Single-belled Energy Pile Under Summer Conditions

作　　者：周杨[1,2] 孔纲强[1] 李俊杰[2] ZHOU Yang;KONG Gang-qiang;LI Jun-jie(Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,Hohai University,Nanjing 210098,Jiangsu,China;College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210098,Jiangsu,China)

机构地区：[1]河海大学岩土力学与堤坝工程教育部重点实验室,江苏南京210098 [2]河海大学水利水电学院,江苏南京210098

出　　处：《中国公路学报》2023年第5期65-74,共10页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(52108313,51778212);中国博士后科学基金项目(2021M690884)。

摘　　要：能量桩是一种兼具承载性能和换热载体双重功能的建筑节能新技术。将大直径扩底灌注桩内部的声测管底部连通形成环路,在桩基完整性检测完成后作为浅层地温能换热管道,即可形成大直径扩底能量桩。依托南京市某扩底桩基础工程项目,开展建筑荷载与温度联合作用下大直径扩底能量桩的热力响应特性现场试验;实测夏季工况下桩身温度与应变的发展规律,初步探讨热致应力变化规律。基于荷载传递法,考虑桩体温度不均匀分布及扩大头的作用,建立热力耦合作用下扩底能量桩工作特性的简化分析方法,分段求解得到任意温度-荷载组合作用下的桩体变形和桩身应力;通过与现场试验数据进行对比,验证了理论方法的可靠性。研究结果表明:桩顶建筑荷载会使桩顶的约束增大1~1.25倍;相较于等直径桩,扩底桩能够减少约26%的桩端应力,扩大头可有效提高能量桩在温度-荷载联合作用下的承载潜能。Energy piles are a new energy-saving technology with conventional bearing capacity and heat transfer carrier functions.Large-diameter belled piles are widely designed to bear the load of the superstructure.The bottom of the acoustic pipe in a large-diameter belled cast-in-place pile is connected to form a loop,and a large-diameter belled energy pile can be formed after the completion of pile foundation integrity testing.Based on a pile-raft foundation project in Nanjing,China,field tests of the thermomechanical characteristics of a large-diameter belled energy pile under building and thermal loads were performed.The development of the temperature and strain of the pile body under heating conditions was measured,and the variation law of the thermal stress was preliminarily investigated.Based on the load transfer method and considering the nonuniform distribution of the pile temperature and the effect of the belled head,a simplified analysis method for the working characteristics of a belled energy pile under thermomechanical loads was established.The pile deformation and pile stress under thermomechanical loads can be obtained by solving the problem in sections.The reliability of the proposed method is verified by comparing it with field test data.The construction load on the top of the pile increases the restraint of the pile head by approximately 1-1.25 times.Compared with an equal diameter pile,a belled pile can reduce the tip stress by 26%.The existence of an enlarged head can improve the bearing potential of an energy pile under thermomechanical loads.

关 键 词：道路工程 能量桩 现场试验 大直径扩底桩 热力响应特性 理论分析 

分 类 号：U416.1[交通运输工程—道路与铁道工程]