| Continuous welded rail (CWR) is a long rail line which is welded by standard length rail together, which eliminates the rail joints so that trains run more smoothly and which is widely used in high-speed railway. When the rail temperature changes, CWR will have a longitudinal temperature force, excessive temperature force may lead to rail broken or rail twisted s threating traffic safety. Therefore, it has a very important significance for the rail maintenance to accurately master the rail longitudinal temperature force distribution and trends inside the rail.In the thesis, the experimental principle of measuring rail longitudinal temperature force is analyzed. Rail strain is measured by the strain electrical measuring method.Data is obtained via the rail longitudinal temperature force monitoring system which is mainly composed of the components of data acquisition, data transfer part and the part of the power supply. Then use the rail strain obtained to solver longitudinal temperature force inside the rail.A three-dimensional finite element model of ballastless track is established. The rail longitudinal temperature force is simulated which the rail body is as the main research object. A high and low temperature box simulation experiment of longitudinal temperature force is conducted, rail longitudinal force acquisition experiments is conducted in the test platform of rail temperature force. And the results show that the anastomosis of simulation and experimental results are good, and this simulation model can response variation of rail longitudinal temperature force with rail temperature.Rail longitudinal temperature force for many situations is simulated and analyzed using the model which has been established. The relation of longitudinal strain and vertical strain caused by the longitudinal temperature force is simulated, and experiment is conducted in the test platform of rail temperature force, the results indicate that the value of the vertical strain caused by the longitudinal temperature force is0.3times of the longitudinal strain; The temperature stress distribution is simulated inside rail, and the results show longitudinal temperature stress in rail waist is the most gentle, which is able to respond to the overall temperature stress of the rail, and the change of longitudinal temperature stress is the largest in rail foot, the buckle pressure has a greater impact on the longitudinal force; The relationship between the extent of the rail fracture and their impact distance under the longitudinal temperature force is simulated, and the results show under20℃temperature drop, the influence distance of fracture10%is480mm, fracture30%is5670mm, fracture60% is9450mm, completely broke the influence distance is19530mm,the greater of the fracture extent, the greater of the impact distance.Field experiments of the longitudinal temperature force are conducted at a ring railway and an intercity railway. Rail longitudinal strain and temperature acquisition tests are conducted in a ring railway, the results show that acquisition error of longitudinal strain and rail temperature is less than±5%. And rail temperature, the longitudinal temperature force and stress-free temperature variation of rail are analyzed in each monitoring point. The trend between longitudinal strain and rail temperature with time is experimented and analyzed in intercity railway, trends of rail temperature and rail temperature force are monitored and analyzed of monitoring points over two months, and find that the longitudinal temperature force is performance for the tension and pressure at the beginning of monitoring, gradually become longitudinal pressure. |
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