沿海环境双块式无砟轨道早期湿度及收缩研究

Early-age humidity and shrinkage of double-block ballastless track in coastal environment

为了研究沿海环境双块式无砟轨道结构早期湿度和收缩应变分布特征,基于ABAQUS子程序HETVAL建立有限元模型,研究混凝土浇筑早期湿度和湿度梯度分布形式,得出道床板收缩应变分布规律。研究结果表明:1)在洒水养护期时,底座板竖向和横向湿度梯度最大值分别为0.68%/mm和0.202%/mm;受环境湿度影响较大的区域为埋深90 mm,底座板内部湿度在龄期28 d时趋于一致。2)轨枕内部相对湿度随着龄期增加而逐渐下降,浇筑第56天时轨枕内部湿度基本一致。3)道床板浇筑后,轨枕表面的最大竖向和横向湿度梯度分别为1.64%/mm和0.59%/mm;在道床板浇筑35 d时,双块式无砟轨道内部湿度基本一致。4)在洒水养护阶段,轨枕与道床板界面的自由收缩应变最大值为270.58×10^(-6);在自然养护阶段,受大气湿度影响,其收缩应变与湿度变化幅度呈线性相关;道床板表面在湿度饱和期的收缩应变占总收缩应变的58.21%。

In order to study the characteristics of humidity field and shrinkage strain in the casting early stage of double-block ballastless track structure on bridge in coastal environment,finite element model was established based on ABAQUS subroutine HETVAL to study the form of humidity and humidity gradient distribution and calculate the distribution law of shrinkage strain of track slab.The results show that:1)The maximum values of vertical and horizontal humidity gradients of the base plate are 0.68%/mm and 0.202%/mm respectively during the sprinkling maintenance period;the area which is more influenced by environmental humidity is buried 90 mm in depth,and the internal humidity of the base plate tends to be consistent at the age of 28 d.2)The relative humidity of the sleeper gradually decreases with the increase of age,and the humidity of the sleeper is basically the same at the 56th day of pouring.3)The maximum vertical and horizontal humidity gradients of the sleeper surface are 1.64%/mm and 0.59%/mm respectively after the track slab is poured;the humidity of the double-block ballastless track is basically the same after the track slab pouring for 35 d.4)The maximum free shrinkage strain at the interface of sleeper and track slab is 270.58×10^(-6) in the sprinkling maintenance stage.In the natural maintenance stage,the shrinkage strain shows fluctuating distribution due to the influence of atmospheric humidity.The shrinkage strain at the surface of track slab in the humidity saturation period accounts for 58.21%of the total shrinkage strain.