地铁钢轨焊缝不平顺对轨道系统振动特性影响的实测研究

Field test analysis of welding unevenness impact on subway track system vibration characteristics

为探究地铁钢轨焊缝不平顺对轨道结构振动特性的影响规律,对0.5 mm焊缝不平顺、0.3 mm焊缝不平顺和无焊缝3种工况进行现场动静态测试,对比了3种工况下轨道部件振动响应的时域、频域以及振动传递特性.研究结果表明:测试区段钢轨焊缝不平顺超标较严重,下行超标率超过50%,且钢轨焊缝形态不一,致使地铁振动显著增大;3种工况下振动响应自钢轨传递至隧道壁逐渐降低,说明由于轮轨间相互作用致使振动主要发生在车轮和钢轨之间;测试路段铺设弹性长枕,振动响应损失主要发生在轨枕与道床之间,减振效果较好,焊缝不平顺工况振动响应损失较大;钢轨存在焊缝时各测点低频振动增加且频谱成分更丰富,影响人们乘坐的舒适性;与无焊缝工况对比,0.3 mm焊缝不平顺工况和0.5 mm焊缝不平顺工况下各测点振动量值最大增幅分别为25%、650%;建议应重点关注焊缝施工工艺和现场验收过程,严格控制钢轨焊缝不平顺不超过规范规定的0.3 mm限值要求.

In order to investigate the impact of welding unevenness on the vibration characteristics of subway track structures,on-site dynamic and static tests are carried out under 3 conditions:0.5 mm welding uneven⁃ness,0.3 mm welding unevenness,and no welds.The time-domain,frequency-domain and vibration trans⁃fer characteristics of the vibration response for rail components under these conditions are compared.The re⁃search results indicate that the welding unevenness of the steel rail in the testing section exceeds the standard significantly,with a downward exceeding rate of over 50%.Furthermore,the varied shape of the steel rail welds leads to a substantial increase in subway vibration.The vibration response from the rail to the tunnel wall gradually decreases under the three conditions,indicating that the vibration mainly occurs between the wheel and the rail due to the interaction between them.The test section equipped with elastic long sleepers,experiences vibration response loss primarily between the sleepers and the track bed.This demonstrates good vibration reduction effects,with significant vibration response loss under uneven welding conditions.When welds are present on the steel rail,low-frequency vibration at each measuring point increases,and the fre⁃quency spectrum becomes richer,affecting passenger comfort.Compared with the condition without welds,the maximum increase in vibration values at each measuring point under the 0.3 mm welding unevenness con⁃dition and the 0.5 mm welding unevenness condition is 25%and 650%,respectively.It is recommended to focus on the welding seam construction process and on-site acceptance process,strictly controlling the un⁃evenness of steel rail welding seams to not exceed the specified 0.3 mm limit in the standard.