Research On Defect Characteristics And Classification Of Higher Speed Rails

According to the field survey results of rail defect on the higher speed line, the defect characteristics of higher speed rail were studied. By analysis of rail rolling contact fatigue, the proposals were put forward to revise classification criteria of rail defect in China, which are closely related to the railway traffic safety under the condition of higher speed.The survey about rail defect was investigated on the typical higher speed track section of mostly Railway Bureaus and the results indicated that except for the traditional defect types there were three new rail defect types including uniform alternation side wear of rail in straight line, rail rolling contact fatigue(RCF) damage and rail wave bend. The features and formation causes of the three new rail defect types were studied and reliable measures were provided in this paper to prevent and solve the rail defect problems on higher speed track.With the changes of railway transport condition in recent years, rail rolling contact fatigue damage has become more and more prominent. The damage not only appears on high rail in curved track, but also on low rail, gauge corner and head surface central section of both rails in straight track. It greatly affects the service life of rail and even endangers traffic safety of railway. In China head checking, squat and spelling are the main performance patterns of rail rolling contact fatigue damage. Concerned with rail rolling contact fatigue damage emerging on Guangshen and Jingguang railway track, and imported heat-treated rail, the thesis mainly analyses and studies head checking damage, its initiation mechanism and whole life model of its propagation. The influence by rail strength grade and rail cant on rail rolling contact fatigue damage was discussed and the corresponding prevention counter measures and recommendations were put forward.On the basis of investigation about service condition and test analysis, the paper dissertates types, states and reasons of rail defect. By referencing domestic and foreign classification methods of rail defect and information of all kinds of typical defects, reference materials were provided to confirm rail defect types for field workers and analyze the reasons for rail defect. Combined with statistics task overview of rail defect in China, the thesis suggests that the classification criteria of rail defect should be revised, and it will have significance of reality.