极端日气温差对单元道床板伸缩变形的影响分析

严寒地区双块式无砟轨道大单元道床板的日伸缩位移幅值与日气温均值存在阶梯型跳跃式的非线性关系,且跳跃时间点对应的日伸缩变化幅值显著放大。为掌握大单元道床板特殊的伸缩变形规律,明确其力学机理,通过对试验数据的统计分析和力学模型的理论推算,得出如下主要结论:严寒地区大单元道床板特殊的伸缩变形行为与极端日气温差的存在密切相关;极端日气温差20℃引起的板端日伸缩变形幅值可达到常见日气温差5~10℃的3.2~10.0倍;大单元道床板日伸缩变化幅值的放大效应与其温度梯度日变化幅值成正比,与其整体温度日变化幅值成反比;极端日气温差引起的极大温度梯度消失时对应的道床板整体温度值存在一定的随机性,由此引发道床板日伸缩位移均值的阶梯型跳跃式发展行为。

Influence Analysis of Extreme Daily Air Temperature Difference on the Telescopic Deformation of Unit Bed Slab

The daily average telescopic displacement of double-block ballastless track's large unit bed slab has a step-type and jumping nonlinear relationship with the mean value of the daily air temperature in the severe cold area, and the amplitude of the daily telescopic change corresponding to the jump time point shows a significant amplification. In order to grasp the special telescopic deformation law of the large unit bed slab and its mechanical mechanism, this paper conducts statistical analysis of the experimental data and theoretical calculation of the mechanical models. The main conclusions are as follows: the large unit bed slab's telescopic deformation in severe cold regions is closely related to the existence of the extreme daily air temperature difference; the daily telescopic deformation amplitude caused by the extreme daily air temperature difference of 20 ℃ can reach 3.2～10.0 times of the common daily air temperature difference of 5～10 ℃; the daily telescopic deformation amplification effect of the large unit bed slab is proportional to the daily variation amplitude of its temperature gradient, and inversely proportional to the daily variation amplitude of its overall temperature; the corresponding overall temperature parameters of the bed slab has a certain randomness in the wake of the disappearance of the extreme temperature gradient caused by the extreme daily temperature difference, which results in the step-type and jumping development behavior of the unit bed slab's mean telescopic displacement.