大跨径无砟连续梁上小阻力扣件的适应性研究

Adaptability study on small resistance fasteners on long-span continuous ballastless bridges

为探究小阻力扣件在高速铁路无砟轨道大跨径连续梁上的适应性,选用经过验证的非线性弹簧模拟梁轨间纵向阻力,建立空间轨-桥-墩-桩基础的一体化有限元模型.以武汉-咸宁城际铁路主跨100m的系列连续箱梁为研究对象,对采用普通扣件与小阻力扣件的桥上无缝线路的各种附加力进行对比研究,并探讨了采用小阻力扣件时,扣件阻力、铺设位置、运营荷载模式及墩台刚度等敏感性参数对梁轨间纵向附加力的影响.研究表明:采用小阻力扣件对挠曲力影响较小,可减小制挠力10%以上,减小轨道和墩台承受的伸缩及断轨附加力40%～57%,但断缝值有较大增长;各敏感性参数对附加作用力有不同程度的影响,参数取值应切合实际,综合比较后选择最优设计.

To investigate the adaptability of small resistance fasteners on long-span continuous bridges on high-speed railways,the integrative spatial finite element model of track-bridge-pier-foundation system was established with the proven nonlinear spring element simulating the longitudinal resistance between track and bridge.A series of continuous beams with the main span of 100 m on the Wuhan-Xianning intercity railway were considered.The various additional longitudinal forces of continuous welded rails using the common fasteners and small resistance fasteners were studied comparatively.The influences of the fastener resistance,laying position,live load mode,and pier’s longitudinal stiffness on the additional longitudinal forces were investigated.Research results indicate that small resistance fasteners have a little influence on additional bending force,but can reduce the additional force simultaneously caused by vertical load and braking load by over 10%.By adopting small resistance fasteners,the additional expansion forces and additional rail-breaking forces in long-span ballastless continuous girder can be reduced obviously by 40%～57%,while greater rail broken gap will appear.Meanwhile,the sensitive parameters discussed have great effect on the additional forces,so the value should be chosen according to the fact,and the optimal value should be adopted by comprehensive comparison during designs.