路基冻胀-融化-沉降组合作用下CRTSⅢ型板式无砟轨道的变形损伤

Deformation Damage of CRTSⅢSlab Ballastless Track Under Combined Action of Subgrade Frost Heave-thaw-settlement

对于我国季节性冻土区高速铁路路基病害,只考虑单一冻胀作用对无砟轨道结构的影响存在一定缺陷。针对这一问题,本文建立CRTSⅢ型板式无砟轨道精细化分析模型,研究了路基冻胀-融化-沉降组合作用下无砟轨道结构的损伤机理和变形规律。结果表明:相较于单一冻胀作用,路基冻胀-融化-沉降组合作用能更加准确反映路基从冻胀到融化过程中轨道结构的变形和损伤;在冻胀-融化-沉降过程中,钢轨、轨道板、底座板三者垂向位移幅值均呈现先增大再减小而后反向增大的趋势;在路基融化回落至4 mm时,底座板和自密实混凝土以及下部路基表层的层间离缝位置均呈现从冻胀波峰两端到冻胀波峰中部的迁移;轨道板损伤只发生在路基冻胀阶段,底座板损伤发生在路基冻胀和融化阶段。

For the diseases of high speed railway subgrade in seasonal frozen soil area in China,there are certain shortcomings in only considering the action of single frost heave on ballastless track structure.In response to this issue,this article would establish a refined analysis model for CRTSⅢslab ballastless track,and studies the damage mechanism and variation laws of ballastless track structure under the combined action of subgrade frost heave-thawsettlement.The results indicate that compared to a single frost heave effect,the combination of subgrade frost heavethaw-settlement can more accurately reflect the deformation and damage of track structures for the process from frost heave to thawing.During the frost heave-thaw-settlement process,the vertical displacement amplitudes of the steel rail,track plate,and base plate all show a trend of first increasing,then decreasing,and then increasing in the opposite direction.When the subgrade thaws and falls back to 4 mm,the interlayer joints between the base plate,selfcompacting concrete,and the surface layer of the lower subgrade all show a migration from the two ends of the frost heave peak to the middle of the frost heave peak.Track plate damage only occurs during the subgrade frost heave stage,while base plate damage occurs during the subgrade frost heave and thawing stages.