Generation And Development Mechanisms Of Rail Corrugation On Subway Track Based On Wheel/Rail Vibration Characteristics

With the expansion of city scale and the increase of travel demand in recent years, existing urban public transport system can not meet the travel requirements of residents any more. In order to increase the transport capacity of urban public transport system and solve the problem of traffic congestion, subway construction has been carried out in many cities in China. However, it can be seen from the operation experience of operation lines that the problem of rail corrugation has occurred on subway lines in different extent in major cities in China. Rail corrugation not only reduces the service life of constituent parts of track structure and increases the workload of maintenance, but also affects the running safety of the train seriously. Therefore, it has great practical significance on ensuring the safe operation of subways to do researches on the generation and development mechanism of metro rail corrugation. Based on this, this paper reveals the reason for the formation and development of metro rail corrugation starting with the analysis of vibration characteristics of wheel/rail system. The specifics are as follows:1. Displacement receptance and corrugation growth rate are selected as evaluation indexes evaluating generation and development of rail corrugation respectively. The concepts of the two indexes are introduced and the derivation process and calculation method of corrugation growth rate are presented emphatically.2. Frequency domain analysis models of4kinds of track structures and wheelset in Beijing subway are established. The track structures are respectively general short sleeper track, vibration absorber fastening track, LVT track and ladder-shaped sleeper track. Peak frequencies of vibration response of each track and wheelset are obtained through modal analysis and frequency response analysis. Then the relationship between corrugation formation and wheel/rail vibration is got by comparing the peak frequency and corrugation passing frequency. Results show that:the vertical vibration of track structure under certain frequency is an important cause of corresponding wavelength corrugation; the vibration of wheelset around310Hz is an important cause of rail corrugation on vibration absorber fastening track; the vibration of wheelset has little effect on the formation of rail corrugation on other three tracks; additional mass of wheelset has larger effect on the formation of long-wave corrugation while less impact on the formation of short-wave corrugation.3. Vehicle-track-tunnel coupled time domain analysis models are established to calculat time-history distributions of dynamic indexes of track. Then the indexes above are converted to the frequency domain to study the vibration characteristics of track structure under the train load and track irregularity excitation. Results show that: multiple vibration response peaks of rail exist within1000Hz; good agreement between peak frequency and corrugation passing frequency exists, indicating that the inherent vibration of track is an important reason of rail corrugation.4. Development mechanism of rail corrugation on different tracks is studied based on corrugation growth rate. Then the influence law on corrugation growth trend caused by the influencing factors is analyzed such as curve radius, different positions between adjacent sleepers, train speed and wheel/rail friction coefficient. Results show that:rail corrugation has large increasing trend around corrugation passing frequency; among4different tracks, vibration absorber fastening track is most prone to produce corrugation while general short sleeper track is least prone to produce corrugation; among4wheels of leading wheelset and draging wheelset, the interaction between inner wheel of leading wheelset and rail makes the maximum contribution to corrugation growth; increasing curve radius will help slow down the development trend of corrugation; in the high frequency band, corrugation development trends are quite different at top of the sleeper and mid span of adjacent sleepers, which can lead to the formation of high-frequency short-wave corrugation; train speed has little effect on the formation of long-wave corrugation while large effect on the formation of short-wave corrugation; reducing wheel/rail friction coefficient significantly slows down the development trend of corrugation.