双块式无砟轨道道床板早期温度场特性研究

Research on the Early Temperature Field Characteristics of Double-block Track

研究目的:为探究道床板早期温度场变化特性,确定温度应力的起点温度,本文建立无砟轨道温度场计算模型且用试验验证模型的准确性,并考虑道床板混凝土水化热效应及养生方式的影响,计算分析浇筑初期道床板零应力温度等指标。研究结论:(1)在道床板混凝土浇筑前3天水化热对早期温度场影响显著,道床板在不同浇筑时刻的零应力温度差别显著,T1最大值一般出现在4:00~8:00时间段内浇筑的混凝土中,最小值一般出现在20:00左右浇筑的混凝土中,上午浇筑的混凝土比下午浇筑的T1值高;(2)塑料薄膜养生下道床板的早期温度T1、Tmax最大,自然养生和绝热养生次之,土工布养生最小,土工布和塑料薄膜养生下的板中T1、Tmax均高于浇筑温度20℃左右;(3)浇筑温度对道床板零应力影响较大,取浇筑温度为初始温度的方法会大大低估降温幅度值;(4)本研究成果可为双块式无砟轨道的设计、施工及养护维修工作提供一定的理论依据。

Research purposes:In order to research the changing characteristics of the temperature field of slab track in early stage and find out the initial temperature causing temperature stress,the temperature field computing model of ballastless track was established,and its correctness was validated by the experimental results.Taking the hydration heat and curing method of track slab into account,the zero-stress temperature at the initial stage of concrete pouring was analyzed.Research conclusions:(1)In the first three days of concrete pouring,the hydration heat has significant impact on the early temperature field of slab track.With different casting time,the zero-stress temperatures vary greatly.Generally speaking,the maximum first zero-stress temperature(T1)is occurred in the slab track which is casting during 4:00 am^8:00 am,while the minimum T1 is occurred in the slab track which is casting at 8:00 pm.The T1 which is casting on morning is higher than that on afternoon.(2)The early T1 and Tmax of slab track cured by plastic film is maximum,and that cured by geotechnical cloth is minimum,and both of them are 20℃higher than concreting temperature.(3)The concreting temperature has obvious influence on the zero-stress temperature,so it may severely underestimate the cooling temperature when the concreting temperature was considering as the initial temperature.(4)The research results can provide a certain theoretical basis for the design,construction and maintenance of double-block track.