Study On Monitoring Longitudinal Stress In Continuous Welded Rail Based On Strain Electrical Measuring Method

Continuous welded rail(CWR) is welded by standard unit rails together, which is cancelled connection joints between traditional rails. It is a widely used track form that can meet the comfortable needs for the rapid development of high-speed railway. There is great longitudinal stress in it when the rail is affected by the wheel rolling, the ambient temperature changing and other factors in operating. Rail crawling will happen when the rail stress is bigger than the resistance of fasteners and ballast bed. Stress concentration and uneven distributionis will be produced due to the crawling, and this will affect the stability of rail track. There is a great significance to monitor the state of rail stress in advance.In this paper, longitudinal strain and temperature in CWR was monitored based on strain electrical measuring method, and wireless sensor network was used to transmit and gather them. Longitudinal stress and locked temperature vibration were calculated through the strain and the temperature. The feasibility measurement scheme based on strain electrical measuring method was studied, and sensors for collecting the strain and the temperature were arranged reasonably. Installation process for strain sensor was made according to the CWR field work environment. At the same time, a kind of location marking tool and clamping device were designed for improving the efficiency, accuracy and consistency of strain gauge installation.Sensors were made and integrated in the laboratory. Temperature drifts and stress calibration test were carried on the integrated sensor units which was in order to improve the stability and accuracy of them for long-term monitoring.The integrated sensor measurement unit and system of it were installed in a inter-city rail line and experimental base.A software for analyzing the stress in CWR based on the MATLAB. Rail stress and lock temperature vibration were compared and analyzed from the26monitoring points installed in the experimental base. The monitoring data showed that the stress of the monitoring positions in the main line was about-40-+75Mpa in the inter-city rail and it was about±35Mpa near the rail joints positions in the experimental base. The stress away from the rail joints was bigger and stable about-30-+75Mpa. The lock locking vibration was within±3℃at the monitoring positions of the fastened rails, which conformed the railway standard for the safety threshold range of it.