桩顶荷载作用下细长能源桩承载特性试验  

Study on Bearing Characteristics of Slender Energy Piles with Load on Top

作　　者：陈龙[1,2] 胡逸凡 陈永辉 黄铭[4] 张体浪 CHEN Long;HU Yi-fan;CHEN Yong-hui;HUANG Ming;ZHANG Ti-lang(Key Laboratory of Geomechanics and Embankment Engineering,Ministry of Education,Hohai University,Nanjing 210024,Jiangsu,China;Institute of Ocean and Offshore Engineering,Nantong Hohai University,Nantong 226334,Jiangsu,China;Suzhou Industrial Research Institute,Hohai University,Suzhou 215000,Jiangsu,China;The Second Construction Co.Ltd.,of China Construction Seventh Bureau,Suzhou 215000,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,江苏南京210024 [2]南通河海大学海洋与近海工程研究院,江苏南通226334 [3]河海大学苏州产业研究院,江苏苏州215000 [4]中建七局第二建筑有限公司,江苏苏州215000

出　　处：《中国公路学报》2025年第1期83-94,共12页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(52478335,52178327);中央高校基本科研业务费专项资金项目(B210202032)。

摘　　要：基于离心机模型试验,对不同桩顶荷载下的细长摩擦型能源桩进行了长达30年的热-冷循环温度作用,研究桩顶荷载作用对于细长能源桩承载特性的影响。离心机加速度为70g,模型桩由铝管制成,整个桩身范围均匀设置5组应变计和6组热敏电阻用来测量桩身轴力和温度。采用标准丰浦砂作为桩周土体及桩底持力层试验材料,对桩顶自由和有桩顶荷载的能源桩施加30次热-冷循环。研究结果表明:对于长径比为50的细长桩,最大轴力出现在桩身中下部约3/4深度处,这是桩身下部温度变化以及桩侧土体给桩的摩阻力变化两者之间耦合作用的结果;循环温度作用对桩身轴力的影响主要集中在首次循环;桩身细长使得摩擦桩桩端具有一定的端承效应,在热循环阶段,细长桩桩端会存在较大的嵌固深度,使得下部轴力变化量较大;在冷循环过程中,存在桩顶作用的细长桩,桩身下部具有更深的嵌固距离;同时,桩顶荷载的施加可以减少桩身轴力衰减以及加热引起的桩侧负摩阻力。能源桩的桩基承载力会存在一定程度的折减,对于上覆荷载与长期循环温度荷载联合作用下的能源桩,在保持桩顶荷载不变的情况下,其承载能力较桩顶自由的能源桩降低14.8%。因此,在设计中应考虑其长期承载特性。To study the effect of the load on bearing characteristics of slender energy piles,a centrifuge model test was conducted with different loads applied on slender frictional energy piles,and the energy piles were subjected to 30-year thermal-cold cycles.The centrifuge acceleration was 70g.The model pile was composed of aluminum tube.Five groups of strain gages and six groups of thermistors were set uniformly throughout the pile body to measure the axial force and temperature.Standard Fengpu sand was used as the test material around the pile and bearing layer of the pile bottom.30 hot-cold cycles were applied to the energy piles with free and top loads.In a slender pile with a length-to-diameter ratio of 50,the maximum axial force occurs at 3/4 of the depth in the middle and lower parts of the pile approximately,as a result of the coupling effect between the change in temperature and the friction resistance at the lower part of the pile.The influence of the circulating temperature on the axial force of the pile is primarily concentrated in the first cycle.The slender pile body causes the tip of the frictional pile to exhibit a certain end-bearing effect.In the thermal cycle stage,the end of the slender energy pile exhibits a large embedment depth,and the axial force of the lower part changes significantly.During the cold circulation process,slender piles with load on the top have a deeper embedment distance at the lower part of the pile body.The application of pile-top loads can reduce the attenuation value of the pile shaft axial force and the negative friction resistance on the pile side caused by heating.For energy piles subjected to a combination of top load and long-term cycle temperature,the bearing capacity of the energy pile foundation is reduced to a certain extent.The bearing capacity of the pile head reduces by 14.8%compared with that of the energy pile with a free pile head,while keeping the pile head load unchanged.Therefore,the long-term bearing characteristics of energy piles should be considered in t

关 键 词：路基工程 能源桩 离心机试验 细长桩 承载特性 

分 类 号：U416.1[交通运输工程—道路与铁道工程]