专用铁路简支梁桥上铺设50m长钢轨预留轨缝研究

Research of Reserved Joint Gap of 50 m Rail on Simply Supported Beam Bridges for Access Railroad

为确定常用跨度简支梁桥上50 m长钢轨合理的预留轨缝,基于梁轨相互作用原理,建立了钢轨-接头-轨枕-桥梁-墩台一体化计算模型,并从5×32 m简支梁桥上梁轨相互作用引起的钢轨及桥墩纵向受力两方面验证了模型的正确性。以某专用线上的10×32 m简支梁桥为例,分析了轨温变化幅度、基本轨接头阻力、护轨阻力等对桥上50 m长钢轨接头轨缝改变量的影响。研究结果表明:梁轨相互作用对桥上50 m长钢轨接头轨缝会产生显著影响,并且影响程度与接头所处位置相关;轨缝改变量随着基本轨接头阻力和护轨扣件阻力的增加而降低,受护轨接头阻力和墩台纵向水平刚度的影响较小;跨度为24 m、32 m简支梁桥上铺设50 m长钢轨的接头螺栓扭矩应按照900N•m设计,且运营中还应该加强螺栓扭矩检查,确保降幅不超过15%。

To determine the reserved joint gap of 50 m rail on common span simply supported beam bridges for access railroad,a rail-joint-sleeper-bridge-pier calculation model based on the theory of bridge-track interaction was established.A correctness study of the model was conducted via two aspects of longitudinal force of rail and piers caused by bridge-track interaction on a 5×32 m simply supported beam bridge.Taking a 10×32 m simply supported beam bridge for access railroad as an example,the influence of rail temperature variation,joint resistance of stock rail,resistance of guard rail on rail joint gap variation was analyzed with the calculation model.The results show that the bridge-track interaction has a significant impact on rail joint gap variation of 50 m rail on bridges.The degree of impact is also related to the location of rail joints.The variation of 50 m rail joint gap decreases with the increase of joint resistance of stock rail and fastener resistance of guard rail.The joint resistance of guard rail and longitudinal stiffness of piers have little effect on the variation of 50 m rail joint gap.When 50 m rail is laid on 24 m and 32 m simply supported beam bridges,the torque design value of joint bolts should be more than 900 N•m.The torque also should be checked frequently to make sure the reduction is less than 15%.