列车荷载下桥上CRTS Ⅲ型板式无砟轨道挠曲力与位移

针对中国自主研发的CRTSⅢ型板式无砟轨道在运营阶段的受力变形问题, 以梁-板-轨相互作用原理为基础, 考虑钢轨、轨道板、自密实混凝土层及底座板等细部结构的空间尺寸与力学属性, 运用有限元法建立了高速铁路桥上CRTSⅢ型板式无砟轨道无缝线路精细化空间耦合模型; 计算了列车荷载作用下轨道及桥梁结构的挠曲力与位移, 分析了不同列车荷载作用长度、桥上扣件纵向阻力及墩台顶固定支座纵向刚度对挠曲力与位移的影响。研究结果表明: 在全桥加载情况下, 多跨简支梁桥上钢轨挠曲力在支座处表现为拉力, 跨中表现为压力, 大跨连续梁主桥上钢轨挠曲力在两侧边跨表现为拉力, 中间跨表现为压力, 单线加载时2种桥上有载侧钢轨挠曲力分别达到了38、53 kN, 约为双线加载时的1/2;轨道、桥梁结构纵向力与位移最大值不同时出现在同一工况下, 需要根据不同的检算部件选取最不利的列车荷载作用长度, 并将ZK活载中的集中力设置在跨中位置; 采用小阻力扣件可以改善钢轨受力与变形, 简支梁桥和连续梁桥上钢轨最大挠曲力分别减小了35%和22%, 钢轨纵向位移分别减小了7%和5%, 但轨板相对位移分别增大了26%和30%, 需加强观测以控制钢轨的爬行; 从轨道及桥梁结构的安全性与耐久性角度考虑, 建议将墩台顶纵向刚度控制在设计值的1.0~1.5倍范围内。 

Deflection force and displacement of CRTS Ⅲ slab track on bridge under train load

To study the loading and deformation of independently developed China rail track system (CRTS) Ⅲ slab tracks in the operation stage, based on the beam-slab-rail interacting principle, with full consideration of both the dimensions and mechanical properties of detail structures such as rail, track slab, self-compacting concrete layer, and bed plate, a refined space coupling model for continuous welded rails of CRTS Ⅲ slab tracks on a high-speed railway bridge was established using finite element method.The deflection force and displacement of rails andbridge structure under train load were calculated.The effects of load action length, longitudinal resistance of fasteners and longitudinal stiffness of fixed bearings atop the abutments on deflection force, and displacement were analyzed.Analysis result indicates that with the entire bridge loaded, the deflection force of the rail on the multi-span simply supported beam bridge is expressed as tension at the supports and as pressure on the mid-span.While the deflection force of the rail on the main bridge of the long-span continuous beam is expressed as tension on both sides and as pressure on the mid-span.Under the single-line loaded condition, the deflection forces of the loaded side rail on the two bridges reach 38 and 53 kN, and is approximately half of the results under the double-line loaded condition.The maximum longitudinal force and displacement of track and bridge structures will not occur under the same condition.Thus the most unfavorable condition shall be selected based on the different parts to be examined and calculated, to set the concentrated force in ZK train load to the mid-span position.The application of small resistance fasteners changes the stress and deformation acting on the rails, with the maximum deflection forces on rail of the simply supported beam bridge and continuous beam bridge decrease by 35% and 22% respectively, and the maximum longitudinal displacement on rail decrease by 7% and 5% respectively. On the contrary, the relative displacement between track slab and rail increase by 26% and 30%, which necessitates continual observation to keep rail creeping under control.From the perspective of safety and durability of tracks and bridge structures, it is proposed that the longitudinal stiffness atop the abutments be kept within 1.0-1.5 times of the design value.