夏季高温双块式无砟轨道道床板早期温湿度分布特征

Early temperature and humidity distribution characteristics of double-block ballastless track slab in summer

为了研究夏季高温道床板浇筑早期温度和湿度分布规律,制作了新建高铁桥上双块式无砟轨道道床板试验模型,开展了道床板浇筑早期温湿度长期监测试验,研究了温湿度分布规律和温度竖向、横向和纵向分布形式,并基于GEV模型提出了日温度最值代表值和日最大竖向正、负温度梯度代表值。研究结果表明:1)当龄期为11 h时,道床板温度达到最大值;在水化热影响下,浇筑后92 h内道床板温度随着埋深增加而呈递增趋势,随后受气温影响,温度呈相反规律变化;纵向板中湿度减小率比板端的高;2)道床板竖向温度是埋深和时间的非线性函数,分布呈“抛物线”形;埋深100~230 mm是高温核心区;道床板板中处竖向温度梯度最大,且竖向温度梯度随着埋深增加呈现出较大差异性;3)受线路走向影响,横向温度呈凸形非对称分布;纵向温度梯度较小,为了简化计算可以忽略不计;4)板中竖向负温度梯度代表值为67.17℃/m,大于规范值,建议竖向温度梯度取值在有条件情况下可根据现场实测数据确定;5)道床板早期温湿度、竖向温度梯度分布应重点研究板中断面,为了防止道床板浇筑后表面出现裂纹,应注重洒水养护,尤其是道床板板中洒水要均匀且充足。

In order to study the early temperature and humidity distribution characteristics of slab in summer,the test model of the double-block ballastless track slab on the bridge was made.The long-term monitoring test of temperature and humidity in the early stage of slab was carried out.The distribution law of temperature and humidity and the vertical,horizontal and longitudinal distribution of temperature were studied.Based on the GEV model,the representative value of daily maximum temperature and daily maximum vertical positive and negative temperature gradient were proposed.The results show that:1)The temperature of track slab reaches the maximum value when the age is 11 h.Under the influence of hydration heat,the temperature of track slab increases with the increase of burial depth within 92 h after pouring,and then is affected by the temperature,but the temperature shows the opposite law.The humidity reduction rate in the longitudinal track slab is higher than that in the track slab end.2)The vertical temperature of track slab is a nonlinear function of burial depth and time,and its distribution is'parabola'.The burial depth of 100−230 mm is the high temperature core area.The vertical temperature gradient in the middle of track slab is the largest,and the vertical temperature gradient values show great differences with the increase of burial depth.3)Affected by the line direction,the horizontal temperature has a convex asymmetric distribution.The longitudinal temperature gradient is small and can be ignored in order to simplify the calculation.4)The representative value of the vertical negative temperature gradient in the middle of track slab is 67.17℃/m,which is greater than the code value.It is recommended that the vertical temperature gradient value should be determined according to the field measured data under conditions.5)The early temperature and vertical temperature gradient distribution of track slab should be focused on the middle section of track slab.In order to prevent cracks on the surface of track slab after pouring,attention should be paid to the maintenance of water spraying,especially water spraying in the middle of track slab should be uniform and sufficient.