非均匀冻胀条件下铁路纵向变形模型及参数分析

我国是冻土分布大国，寒区铁路轨道普遍遭受地基土冻胀影响。以往的研究偏重地基土的冻胀特征，而对纵向非均匀冻胀变形下铁路与地基土的相互作用关注较少。基于双层弹性地基梁理论，建立铁轨-轨下基础在非均匀冻胀变形作用下的力学模型，给出模型的解析解，结合算例分析夹层弹性系数和冻胀量对轨道位移和内力的影响。结果表明：弹性夹层可以有效减弱铁轨的冻胀变形和应力响应，有利于维护铁轨的运营；铁轨和轨下基础的过渡段长度、凹凸弯折段处的剪力、弯矩随着冻胀位移的增大而增长；夹层弹性系数增大会导致冻胀力对轨下基础的影响逐渐向轨道转移；过渡段的长度只与冻胀量有关。文章提出的计算方法和分析结论可为寒区铁路设计和运营维护提供科学指导。

Longitudinal deformation model and parameter analysisof railways under nonuniform frost heave

As a country covered by a large area of frozen soil, China''s railway network in cold regions is generally affected by the frost heave of the foundation soil. Although research has focused on the frost heave characteristics of foundation soils, the railway-foundation soil interaction under longitudinal nonuniform frost heave deformation remains unexplored. Based on the theory of double-layer beam on elastic foundation, this study established a mechanical model of a railway-sub-rail foundation under the action of nonuniform frost heave deformation. An analytical solution of the model was derived, and the effects of the elastic coefficient of the interlayer and frost heaving on the displacement and internal force of the track were analyzed by combining with an example. The results showed that the elastic interlayer could effectively reduce the frost heave deformation and stress response of the rail, which is conducive to rail operation. The length of the transition section between the rail and the sub-rail foundation and the shear force and bending moment at the concave convex bending section increased with the increase in the frost heave displacement. The frost heave force acting on the sub-rail foundation was gradually transferred to the track with the increase in the elastic coefficient of the interlayer. The length of the transition section was only related to the amount of frost heave. The proposed calculation method and the conclusions obtained from the analysis can provide scientific guidance for the design, operation, and maintenance of railways in cold regions.