预应力混凝土箱梁水化热研究测试  

Research and Test of Hydration Heat of Prestressed Concrete Box Girder

作　　者：伍丽[1] Wu Li

机构地区：[1]中铁十八局集团第五工程有限公司,天津300450

出　　处：《辽宁省交通高等专科学校学报》2023年第5期1-5,共5页Journal of Liaoning Provincial College of Communications

基　　金：中国铁建股份有限公司科技研发计划项目(18-C03)。

摘　　要：为了防止施工时预应力箱梁桥主梁混凝土因水化热过高而造成温致裂缝的出现,对两座预应力箱梁桥开展了现场水化热实时监测,同时建立有限元仿真模型分析其水化热应力场和温度场的变化趋势,并对合理拆模时间进行了研究,结果表明:预应力箱梁桥施工时会有较大的水化热产生于主梁根部梁段,通常会持续7天左右,前1至2天温度快速升高至最大值,这时箱梁腹板外部混凝土受力状态为受拉,在4天内先后经历温度的快速升高和快速下降,所以在此过程中会有较大的内外温差,结构容易出现裂缝;建议以水化热为角度来分析确定合理拆模时间,同时确定了正常天气条件下预应力箱梁桥拆模时间应超过4天。In order to prevent the occurrence of temperature-induced cracks in the concrete of the main girder of the prestressed box girder bridge due to excessive hydration heat during construction,the two pre-stressed box girder bridges were monitored in real time on the site of the hydration heat,and a finite ele-ment simulation model was established for analysis.The change trend of its hydration thermal stress field and temperature field,and the reasonable dismantling template time is studied.The results show that:during the construction of prestressed box girder bridges,there will be a large amount of hydration heat generated in the girder section at the root of the main girder,usually It will last for about 7 days,and the temperature rises rapidly to the maximum value in the first 1 to 2 days.At this time,the stress state of the external con-crete of the box girder web is in tension,and it experiences a rapid increase and a rapid decrease in tem-perature within 4 days.In this process,there will be a large temperature difference between the inside and outside,and the structure is prone to cracks.It can be added fly ash to the cement and optimize the con-crete mix ratio to reduce the heat of concrete hydration,so as to avoid cracks in the structure.It is recom-mended to use water taking the heat as an angle to analyze and determine the reasonable dismantling tem-plate time and determined that the demolding time of the prestressed box girder bridge should exceed 4 days under normal weather conditions.

关 键 词：预应力箱梁桥 水化热 温致裂缝 监测 

分 类 号：U448.213[建筑科学—桥梁与隧道工程]