混凝土箱梁水化热温度试验研究

研究目的:温度应力已被认为是混凝土箱梁开裂的主要原因之一。为了掌握水化热温度沿箱梁截面的分布规律,并根据混凝土施工工艺状况,估算温差应力,特对混凝土箱梁进行了水化热温度试验,为箱梁设计与施工提供有益的参考。研究方法:水化热温度测试选取了梁体的跨中及端部截面,按照能够充分反映箱梁水化热变化情况的原则,分别在顶板、底板、腹板布置了内埋式温度传感器,从混凝土入模开始,量测水化热温度的变化情况。研究结果:根据温度测试结果,可以绘制出混凝土水化热温度随观测时间变化的曲线。通过对秦沈客运专线箱梁温度测试结果的总结分析,重点阐述了箱梁混凝土早期水化热温度发展的一般规律,其中包括水化热温度时程曲线的一般形式、温升基本规律、温降基本规律、混凝土的温度梯度、入模温度与温度峰值的关系等,并提出了防止温差过大而引起混凝土开裂的工程措施。

Experimental Research on Hydration Temperature of Concrete Box Girder

Research purposes: Temperature stress was regarded as one of the major reasons of cracking of concrete box girder.For providing design and engineering of box girder with beneficial references,the main purposes of temperature test of hydration are to grasp the regularities of(distribution) of hydration temperature follow box girder section and under considering the state of arts of concrete construction,we estimate temperature stress.Research methods:The tests are carried out on mid-span and tip sections of box girder.With the principle of(disclosing) adequately the developmental rules of hydration of box girder,temperature probes covered in concrete are(arranged) at top tray,soleplate and web.Then the variation of hydration temperature would be measured after concrete placement.Research results:With the results of temperature tests,time-temperature curves of hydration could be drawn.(According) to the test results of hydration temperature of Qinhuangdao-Shenyang Passenger Dedicated Railway Line concrete box girder,the general and(developmental) rules of concrete hydration temperature in earlier phase are discussed,including the commonly form of travel time curve,the basic rules of temperature rise and heat drop,the temperature gradient of concrete and the(relations) between pumping's temperature and thermal spike.Furthermore,the measures which are used to prevent(concrete) cracks caused by great temperature difference are given.