Research On Long Wave S-shape Deformation Of High-speed Railway At The Begin And End Of The Vertical Curve

According to the condition of wheels load function,the track detection technology can be divided into two detection methods: dynamic detection with wheels load function and static detection without wheels load function.The static detection method has high precision,but low efficiency and slow speed.The dynamic detection method has the advantages of small impact on normal operation,high efficiency and fast speed.Because the dynamic detection has the wheel load function,it can truly reflect the operating conditions of the train.The dynamic detection has become the main detection method for the safety status of rail transit infrastructure.The research on the difference between dynamic and static inspection data has always been a very popular topic.By comparing the long wave longitudinal level of the dynamic inspection vehicle with the static inspection vertical deviation data,it is found that there are S-shaped waveform at the begin and end of the vertical curve of the dynamic detection long wave longitudinal level,and the static inspection vertical deviation does not appear similar to the S shape at the same position,and this S-type is universal.According to the phenomenon that there are S-shaped waveform of the long wave longitudinal level of dynamic detection at the begin and the end of the vertical curve,the research goal of this paper is to explore the causes and solutions of the S-shaped deformation of the long wave longitudinal level of dynamic detection.First,analyze the principle of long wave detection of dynamic detection,combined with the principle of static detection of track irregularity,follow the static detection formula of300 m chord track irregularity to determine the calculation method of track irregularity verification calculation of 120 m chord 60 m check.Then use the design line type simulation to calculate the track longitudinal level value after the mileage offset.The obtained analog longitudinal level waveform have high similarity with the motion detection waveform.It is concluded that the mileage deviation of the dynamic detection caused the S-shaped deformation at the begin and end of the curve.Then the cause of mileage deviation are explored.Due to the difference between the type of mileage detected by dynamic inspection and the design mileage.It is concluded that the difference between the track surface mileage detected by the dynamic inspection and the flat design mileage of the ledger is the main cause of the mileage deviation.Finally,examples are used to prove that the track irregularity of the 120 m string caused by the difference between the track surface mileage and the plane mileage at the begin and end of the vertical curve is similar to the S-type of the long wave longitudinal level of the dynamic detection.The research results have reference value for the analysis and application of high-speed rail track dynamic inspection data.