Abstract:
The actual stress-free rail temperature is very important to ensure the safety of high-speed railway operation and guide the line maintenance. With Wufengshan Yangtze River Bridge as the background, the variations of the actual stress-free rail temperature before and after the line operation and its causes were analyzed through the field measurement data. Furthermore, the spatial coupling model of CWR (Continuous Welded Rail)-kilometer-level span bridge was constructed based on the finite element theory. The mapping relationship between the longitudinal and vertical spatial deformation of the bridge and the longitudinal additional force of the CWR under the load of vehicles and temperature was studied numerically. On this basis, a method for measuring the actual stress-free rail temperature of CWR on the kilometer-level span bridges was proposed. The results show that the additional force of the CWR on the kilometer-level span bridge is complex and large. As a result, the existing test methods can not obtain the real and accurate actual stress-free rail temperature of the rail. On the main span, the expansion force and the longitudinal displacement, the deflection force and the vertical deformation all show an obvious linear relationship; the temperature has an obvious linear relationship with the temperature deflection force and the expansion additional force. Based on the linear relationship, an actual stress-free rail temperature monitoring method was proposed which can eliminate the influence of additional forces. The research results can provide a reference for the monitoring point layout and maintenance & repair of CWR on the kilometer-level span bridges.