弹性支撑块式无砟轨道力学特性研究

Research on the Mechanical Characteristics of Low Vibration Track

研究目的:由于隧道内净空的限制,重载铁路长大隧道内宜铺设无砟轨道,弹性支撑块式无砟轨道(LVT)以其良好的减振性能逐渐在重载铁路中得到应用。为研究不同轴重和加载方式下LVT结构的应力应变特性,本文以蒙华铁路重载铁路隧道应用的LVT为例,通过建立LVT结构有限元模型,以探讨LVT结构的受力与变形特征,为LVT轨道结构的优化以及设计施工提供理论依据。研究结论:(1) LVT结构能够保证30 t轴重下静力学性能安全性,当轴重由30 t提高至42 t,钢轨弯矩、轨道结构部件应力及位移幅值增长量在40%左右;横向荷载对轨道结构横向位移及应力的影响显著,板端加载时道床板及底座板应力增量分别为284%、1 000%;(2)横向荷载作用下,除支承块横向应力下降,钢轨弯矩、支承块纵向应力、道床板应力、底座板应力均呈现增长趋势,其中道床板及底座板应力分别增长400%、530%;(3)板端加载时荷载由相邻扣件共同承担,扣件节点反力峰值有所下降,荷载作用点下竖向荷载分配比例由2∶1降低至4∶1,横向荷载分配比例由67%降低至47%;(4)本研究结果对重载铁路中LVT轨道结构的设计和施工有指导意义。

Research purposes: Due to the limitation of tunnel headroom,ballastless track should be laid in the long tunnel of heavy-haul railway. Low vibration track( LVT) is gradually applied in heavy-haul railway because of its good vibration reduction performance. To study stress-strain characteristics of the LVT structure under different axle loads and load type by establishing the finite model of LVT,this paper takes the LVT applied in the heavy-haul railway tunnel of Menghua railway as an example,and by establishing the finite element model of LVT structure,discusses the stress and deformation characteristics of LVT structure,to provide a theoretical basis for the optimization and design and construction of LVT track structure.Research conclusions:( 1) The LVT structure can ensure the safety of static performance under 30 t axle load. When the axle load is increased from 30 t to 42 t,the increase in the bending moment of the rail,the stress and displacement amplitude of the track structure components is about 40%;The lateral load has significant influence on lateral displacement and stress of the track structure,and the stress increments of the track bed slab and the base slab are284% and 1000% respectively when the slab end is loaded.( 2) Under the action of lateral load,except for the decrease of the lateral stress of the support block,the bending moment of the rail,the longitudinal stress of the support block,the stress of the track bed slab and the base slab all show an increasing trend,of which the stress of the track bed slab and the base slab increase by 400% and 530% respectively.( 3) When the slab end is loaded,the load is shared by the adjacent fasteners,the peak value of the fastener node reaction force decreases,the vertical load distribution ratio under the load application point is reduced from 2 ∶ 1 to 4 ∶ 1,and the lateral load distribution ratio is reduced from67% to 47%.( 4) The research result can provide guidelines for the design and construction of LVT structure on the heavy-haul railway.