简支梁桥上无缝道岔温度力与位移影响因素分析

Analysis of the Influence of Some Parameters on the Temperature Force and Displacement of Seamless Turnout on Simple-Supported Beam Bridge

将道岔、梁和墩台视为一个系统,建立简支梁桥上无缝道岔的有限元模型。根据变分原理和“对号入座”法则建立有限元方程组。以铺设一组43号道岔的18跨32 m混凝土简支梁桥为例,研究影响简支梁桥上无缝道岔受力与位移的因素,如支座布置形式、轨温变化幅度、梁温差、扣件阻力、道床阻力、限位器间隙、岔枕刚度、限位器位置、梁跨长度和桥墩刚度等。计算结果表明,简支梁桥上无缝道岔在温度荷载作用下,钢轨温度力在限位器处和限位器前梁端处同时出现两个峰值;与桥上无缝线路相比,桥上无缝道岔桥墩处的最大受力显著增大;当梁与导轨同向伸缩时,岔区内钢轨位移较大;限位器应布置在梁跨中部;限位器间隙对桥上无缝道岔的受力与位移有双重影响;岔区内钢轨的受力与位移随桥墩刚度增大而减小;岔区内采用较大的扣件阻力和道床阻力,岔区外采用较小的扣件阻力和道床阻力,可以降低钢轨附加温度力。

A finite element model of the seamless turnout on simple supported beam bridge was established by regarding the turnout, beam and pier as one system. The nonlinear equation sets of the model were established by the variational principle and the “set-in-right-position” rule. An example was presented in which a No. 43 seamless turnout was laid on a simple-supported reinforced concrete beam bridge. The span of the beam is 32 meters and the span number is 18. Some parameters influencing the temperature force and displacement of the seamless turnout on simple-supported beam were analyzed, such as the disposal of supports, the algebraic difference between rail temperature and the stress-free temperature, the maximum temperature difference of beam, the fastening resistance, the ballast resistance, the gap limit of spacer, the lateral rigidity of switch tie, the location of spacer, the length of beam, and the stiffness of pier, and so on. Calculation results show that there are two peak value points in the rail temperature force of seamless turnout on simple-supported beam bridge which lies in spacer and the nearest beam end point before spacer. Compared with CWR on bridge, the maximum longitudinal force of pier in seamless turnout on simple-supported beam bridge increases greatly. When the switch rail and the beam expend or shrink in the same direction, the maximum displacement of rail in seamless turnout increases, and the spacer should be laid in the middle point of the beam. The gap limit of spacer has two side influences on the force and displacement of seamless turnout on simple-supported beam bridge. The rail temperature force and displacement inside seamless turnout decrease with the increase of pier stiffness. Greater fastening resistance and ballast resistance are adopted inside seamless turnout. Smaller fastening resistance and ballast resistance are adopted outside seamless turnout which can reduce the additional temperature force of the rail.