西北严寒地区双块式无砟轨道初期力学性能分析

位于我国西北严寒地区的双块式无砟轨道采用了大单元道床板结构,为掌握该型结构对严寒地区恶劣温度环境的适应能力,了解其力学性能和行为规律,对达坂城地区采用20 m单元道床板的双块式无砟轨道试验段展开试验研究,通过数据分析和理论计算,得出如下主要结论:大单元道床板板端伸缩效应明显,引发轨道结构与基床表层大面积的层间分离滑动;大单元道床板板中部分混凝土开裂严重,年温差循环作用下大单元道床板将呈现"低温小单元组合、高温闭合大单元"的工作模式;试验段中基床表层提供的单位长度层间摩阻力为372 kN/m;极端日气温差的出现显著放大了大单元道床板日伸缩变化幅值,并形成了大单元道床板日伸缩位移均值阶梯型跳跃式发展的行为特性。

Initial Mechanical Properties Analysis of Double-block Ballastless Track in Severe Cold Area of Northwest China

The double-block ballastless track located in the severe cold area of northwest China adopted a large unit bed slab structure, in order to grasp the adaptability of this structure to the harsh temperature environment in severe cold regions and to understand its mechanical properties and behavioral laws, this paper conducted an experimental study on the double-block ballastless track test section with 20 m unit bed slab in Dabancheng area. Through data analysis and theoretical calculations, the following main conclusions were drawn: The large-unit bed slab has obvious expansion and contraction effect, which leads to the large-area separation and sliding between the track structure and the surface layer of subgrade; The concrete in the middle part of the large unit bed slab was severely cracked. Under the annual temperature difference cycle, the large unit road bed will exhibit the working mode of "low temperature small unit combination and high temperature closed large unit"; The unit length interlayer friction resistance provided by the surface layer of subgrade in the test section was 372 kN/m; The occurrence of extreme daily air temperature difference significantly amplifies the amplitude of the daily expansion and contraction of the large-unit bed slab, and forms a step-type jump behavior characteristic of the large-unit bed slab's daily telescopic average displacement.