研究目的: 单元式无砟轨道应用过程中检测出波长与板长相近的周期性不平顺问题,影响了列车运营舒适性。为研究周期性变形的敏感影响因素,以CRTSⅢ型板式无砟轨道为例,建立考虑层间非线性接触关系的无砟轨道多物理场耦合分析模型,分析轨道板内温度梯度和自密实混凝土收缩对轨道板翘曲变形和轨面周期性不平顺的影响程度,获取了两种荷载与周期性变形间传递关系。
研究结论: (1)温度梯度、混凝土收缩等效降温量越大,轨道竖向变形差越大且传递比越大,+90 ℃/m、-45 ℃/m温度梯度时,钢轨垂向变形差分别为0.72 mm、0.32 mm,传递比分别为0.015 8 mm/(℃·m^-1)、0.018 3 mm/(℃·m^-1);(2)等效降温-10 ℃时,钢轨垂向变形差0.39 mm,传递比为0.073 9 mm/℃;(3)与混凝土收缩组合时,正温度梯度变形效应叠加,负温度梯度变形效应抵消,-45 ℃/m温度梯度与混凝土收缩-10 ℃间引起的变形效应相当,可基本抵消;(4)通过控制轨道精调时机,合理预设初始不平顺可减小运营期单元式无砟轨道周期性不平顺;(5)本研究结论可为控制目前广泛存在的无砟轨道周期性变形问题提供理论指导。

Research purposes: In application, periodic track irregularity with the wavelength close to the slab length has been detected on unit ballastless track, which seriously affects running comfort. To analysis the sensitive factors of periodic deformation, taking the CRTS Ⅲ slab track as an example, a multi-physical field coupling analysis model of the ballastless track considering the nonlinear contact relationship between layers is established. The influence of temperature gradient and self-compacting concrete shrinkage in the track slab on the warping deformation and periodic irregularity of the track surface is analyzed, and the transfer relationship between two types of loads and periodic deformation is obtained.
Research conclusions: (1)The greater the temperature gradient and the equivalent temperature decrease of concrete shrinkage, the greater the vertical deformation difference and the greater the transfer ratio of the rail.Under thetemperature gradient of +90 ℃/m and -45 ℃/m, the vertical deformation difference of the rail is 0.72 mm and 0.32 mm, and the transfer ratio is 0.0158 mm/(℃·m^-1) and 0.0183 mm/(℃·m^-1).(2) Under the equivalent temperature decrease of -10 ℃, the vertical deformation difference of rail is 0.39 mm, and the transfer ratio is 0.073 9 mm/℃.(3)When combined with concrete shrinkage, the positive temperature gradient deformation effect is superimposed, and the negative temperature gradient deformation effect is canceled out. The deformation effect caused by -45 ℃/m temperature gradient is equivalent to that caused by concrete shrinkage of -10 ℃, which can be basically canceled out.(4)By controlling the timing of track precise adjustment and presetting a reasonable initial irregularity, the periodic irregularity of unit slab track during operation can be reduced.(5)The research results can provide theoretical guidance for controlling the periodic deformation of ballastless track, which is widely existing at present.