大跨钢桁桥温差变形下无砟道床层间性能研究

Interlayer Performance of Ballastless Track Bed under Temperature Difference Deformation of Long-span Steel Truss Bridge

通过建立大跨斜拉钢桁桥全尺寸模型和多节间钢桁桥上CRTSⅢ型板式无砟轨道空间精细化模型,形成空间多尺度有限元模型;分析钢桁梁在温差荷载作用下的桥面变形曲线与分布特征;针对跨中和主塔处无砟轨道,分析桥面温差变形、自密实混凝土(SCC)层收缩及两者共同作用时道床的层间性能,研究弹性缓冲部件刚度对层间性能的影响。结果表明:(1)主梁温差变形时,Ⅲ型板轨道在跨中、主塔等变形显著位置的适应性良好;梁温差15℃时,层间未出现脱离。(2)叠加考虑SCC凝固收缩时,会产生层间脱空;凸台限位显著影响层间性能,代表性工况跨中下挠时凸台的压应力较上拱时约高80.8%,层间脱空量减小69.4%;主桥负温差超过10℃会加剧跨中层间脱空。(3)增加凹槽垫板刚度,减小弹性隔离层刚度,可缓解层间脱空,建议垫板刚度取250 kN/mm,垫层刚度取0.01 N/mm^(3)。

By establishing a full-scale model of the long-span cable-stayed steel truss bridge and a refined spatial model of the CRTS III slab-type ballastless track on multi-panel steel truss bridges,this paper develops a spatial multi-scale finite element model and analyzes the deformation curve and distribution characteristics of the bridge deck under temperature difference load on the steel truss girders.For the ballastless track at the midspan and main tower locations,the analysis focuses on the temperature difference deformation of the bridge deck,the shrinkage of self-compacting concrete(SCC)layers,and the interlayer performance of the ballast bed under the combined effects of both.This paper also studies the impact of the stiffness of elastic cushioning components on the interlayer performance.The results show that:(1)When the main girder experiences temperature difference deformation,the CRTS III slab-type track exhibits good adaptability at significant deformation locations such as the midspan and main tower.At a temperature difference of 15°C,no delamination was observed between the layers.(2)When considering the solidification shrinkage of SCC,interlayer voids may occur.The flange limitation significantly affects interlayer performance;under representative conditions,the compressive stress on the flange during midspan deflection is approximately 80.8%higher than during camber,resulting in a 69.4%reduction in interlayer voids.Additionally,a negative temperature difference exceeding 10°C on the main bridge exacerbates interlayer voiding at the midspan.(3)Increasing the stiffness of the groove pad and reducing the stiffness of the elastic isolation layer can alleviate interlayer voids.It is recommended to set the pad stiffness at 250 kN/mm and the layer stiffness at 0.01 N/mm^(3).