Research On Detection Technology Of Temperature And Crack Of Ballastless Track Slab In Severe Cold Area

China's high-speed railways crisscross all major cities across the country.The ballastless track technology develops rapidly.The ballastless track lifts the speed limit of the ballasted track on the train,and is widely used due to its high stability and strong durability.But with the accumulation of operating time,the large temperature effect shortcomings of the ballastless track are gradually exposed.Especially on the routes with poor construction quality,the maintenance workload of ballastless tracks has gradually increased.The temperature measurement and disease detection of the ballastless track slab are becoming more and more critical to its safe operation and characteristic research.It is of great significance for the development of temperature and disease detection technology of the ballastless track.Infrared temperature measurement technology is a commonly used non-contact temperature measurement method.This technology detects through the radiant energy of the target infrared band,and has the advantages of non-contact,non-invasive,fast response,and passive measurement.In this paper,infrared temperature measurement technology is used to detect the temperature and cracks of the ballastless track slab.The aims of the thesis are threefol d: First to develop an infrared temperature measurement system for ballastless track slab in severe cold area which is suitable for high-cold and high-speed comprehensive detection trains,to solve the problem of temperature detection of ballastless track slabs;Second to study on the infrared temperature measurement technology of ballastless track slab in outfield,to solve the problem that the calibration environment and measurement environment temperature of the developed infrared temperature measurement system are inconsistent,which affects the measurement accuracy;Third to study on the crack detection technology of ballastless track slab based on single pixel infrared detector,to realize dual parameter detection of temperature and cracks.The main research contents of this paper are as follows:(1)In order to solve the problem of large-scale temperature measurement of ballastless track slab in the outfield,an infrared temperature measurement system for ballastless track slab in severe cold area is developed.The lack of temperature measurement function of ballastless track slab in high-cold and high-speed comprehensive inspection train is solved.The range of the temperature measurement system is-40??60? under the environment of-30??30?.The response speed of the temperature measurement system is better than 2.5ms.According to the requirements,the infrared temperature measuring system adopts a discrete structure.The upper computer of the system performs data processing,including calibration and measurement functions.The slave machine is responsible for radiation energy collection and photoelectric conversion.The slave machine works outdoors in a harsh environment.It is designed with a temperature control system and a cold start system.It is mounted at the bottom of the detection train through a connection structure.In the development process.The signal-to-noise ratio of the selected detector is calculated to ensure that the selected detector can complete the target measurement task of-40?.And the bearing capacity of the designed connection structure is calculated to ensure the safe use of the instrument.The temperature measurement system is calibrated by a surface blackbody.The temperature control range of the developed surface blackbody is -40??60?.And it is realized by constructing a second constant temperature field through a constant temperature bath.(2)In order to measure the large-scale temperature of ballastless track slab in severe cold area based on infrared temperature measurement system,the infrared temperature measurement technology of ballastless track slab in outfield is studied.The research contents mainly include the establishment of infrared temperature measurement model,the research of influencing factors of temperature measurement accuracy and the research of radiation response calculation of low temperature blackbody in band.The research focuses on solving the measurement accuracy problem which is affected by the inconsistency between calibration environment and measurement environment.To solve this problem,a high-precision temperature measurement method for ballastless track slab in outfield is proposed.In this method,the target self-radiation and the reflected environmental radiation mixed together in the calibration process are separated theoretically by two calibration functions at different ambient temperatures.An equivalent blackbody radiation function is constructed.This function accords with the actual measurement scene of the ballastless track slab in outfield,and can be used to improve the temperature measurement accuracy of the ballastless track slab in outfield.The proposed infrared temperature measurement method for ballastless track slab in outfield is verified by experiments,which proves the feasibility of this method.(3)Aiming at the problem of crack detection of ballastless track slab,the research on crack detection technology of ballastless track slab based on single-pixel infrared detector is carried out.The temperature information is used for crack detection in this technology.Light and shadow interference can be avoided.Only the voltage series are collected and compared,so this method has a fast response,and is convenient for high-speed vehicle inspection.This method is based on the situation that the crack can not fill the field of view of the infrared detector.In the research,the crack inspection scene of the ballastless track slab is constructed.Based on the constructed detection scene,the functional relationship between output signal and cracks width is established.According to this function relationship,the crack width in the field of view can be calculated.According to the established functional relationship,simulation research es are carried out: a)observing the changing trend of the output signal when there are cracks;b)the relationship between crack width and output voltage change;c)the relationship between the radius of the field of view and the width of the detectable crack.Finally,the millimeter-level crack detection simulation experiment was carried out,which verified the feasibility of the detection method.(4)In the laboratory,response speed verification experiment,environmental temperature adaptability verification experiment,and uncertainty analysis are carried out on the developed infrared temperature measurement system for ballastless track slabs in severe cold areas.The response speed of the system is verified by an experiment,using the infrared temperature measurement system and a turntable with a linear speed exceeding 360km/h.The environmental temperature adaptability verification experiment was carried out,using an infrared temperature measurement system and a high and low temperature test chamber.Repeated measurement experiments are performed using the calibrated infrared temperature measurement system,and uncertainty analysis is performed based on the measurement results.