高海拔地区桩基混凝土硬化时期热力响应特性现场试验  

Field tests on thermal response of pile foundation concrete in high altitude localities during hardening period

作　　者：王天赐 孔纲强[1] 刘汉龙[2] 刘星 王成龙[2] 朱鹏熹 WANG Tianci;KONG Gangqiang;LIU Hanlong;LIU Xing;WANG Chenglong;ZHU Pengxi(Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,Hohai University,Nanjing 210024,China;School of Civil Engineering,Chongqing University,Chongqing 400045,China;China State Construction Engineering Corporation Limited,Beijing 100029,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]重庆大学土木工程学院,重庆400045 [3]中国建筑股份有限公司,北京100029

出　　处：《铁道科学与工程学报》2023年第11期4140-4150,共11页Journal of Railway Science and Engineering

基　　金：国家自然科学基金优秀青年基金资助项目(51922037)。

摘　　要：高原地区高海拔、大温差和低气压的特殊环境,会导致早龄期混凝土水化热问题区别于其他地区。目前,针对减小高原地区早龄期混凝土水化热温差、加快高原地区混凝土水化热消散机理尚不清楚。通过在桩基混凝土结构中埋设换热管,建立循环换热系统,开展高原地区桥梁桩基早龄期混凝土水化热消散现场试验。实测桩基混凝土的水化热温度和热致应变变化,获得埋管式循环系统对桩身水化热温度场和应力场的规律,并初步探讨与其他地区的差异性。研究结果表明:本文试验条件下,通过水泵、循环水管、水箱等设备组成的埋管式循环系统可以用于加快高原地区早龄期混凝土的水化热消散以及减小高原地区早龄期混凝土温差;与桩-土之间的热传导相比,埋管式循环系统能够加速混凝土的水化热消散进程,通过循环管中的换热介质将水化作用的热量传递到地面外部环境中,可降低水化热的峰值温度约2~4℃,相应龄期提前约37~58 h;埋管式循环系统能够明显降低桩底部的应变变化范围,能够减小桩基早龄期混凝土的桩身应力,桩身最大约束应力(0.7倍桩长处)降低约23.6%;埋管式循环系统还能够降低混凝土水化进程中的第二零应力温度,提高早龄期混凝土的温降裂缝能力。研究结果对高原地区桩基早龄期混凝土的水化热进程控制和抗裂性能分析有一定的参考价值。The plateau area's special climate of high altitude,huge temperature changes,and low pressure will cause a different hydration and heat problem in early-age concrete than in other regions.At present,the mechanism of temperature difference of hydration heat of early age concrete in plateau area and accelerating the dissipation of hydration heat of concrete in plateau area is still unclear.Field tests of the heat dissipation of hydrated early-age concrete bridge pile foundations in the plateau area were carried out by embedding heat exchange tubes in pile concrete structures and establishing a circulating heat exchange system.The temperature and strain of pile concrete hydration heat were measured.The rule of temperature and stress field of hydration heat of pile body induced by a buried pipe circulation system was obtained,along with a preliminary discussion of differences with other areas.The results show that under the experimental conditions,the buried pipe circulation system consisting of water pump,circulating water pipe,water tank and other equipment can be used to accelerate the dissipation of hydration heat of early age concrete and reduce the temperature difference of early age concrete in plateau area.Compared with the heat diffusion between piles and soils,the buried pipe circulation system can accelerate the dissipation process of hydration heat of concrete.Through the heat exchange medium in the circulation pipe,the heat of hydration is transferred to the external environment of the ground.The peak temperature of hydration heat is reduced by about 2~4℃,and the corresponding age is advanced by about 37~58 h.The buried pipe circulation system can obviously reduce the strain variation range at the bottom of pile,reduce the pile stress at early age of concrete,and reduce the maximum constraint stress(0.7 times pile strength)by 23.6%.The buried pipe circulation system can reduce the second zero stress temperature in the hydration process of concrete and improve the temperature-reducing cracking ability o

关 键 词：高原地区 高寒地区 水化热 桩基 现场试验 

分 类 号：TU93[建筑科学—结构工程]