Research On Sleeper Void Mechanism Under The Coupling Action Of Train Load And Water Of Twin-Block Track

Currently, twin-block ballastless track structure has been widely used in our country. According to the investigation and survey of the service condition of the twin-block ballastless track, varying degrees of failure and damage occurs, especially in the rich rainfall areas or the poor drainage lot, in which the breakage rate of ballastless track is higher than that in the arid area. Present domestic and foreign researches are not systematic and little experience is available as reference. Therefore, the research is carried out and focused on the loosening of twin-block ballastless track sleepers under the coupled action of train load and water. Basic theoretical issues of water induced damage of ballastless track are investigated, which contributes to the development of ballastless track design and maintenance. The research results are meaningful for extending longevity and are listed as follows:Firstly, through the on-site investigation and survey of the actual situation of the water induced damage of ballastless track, combining with the research situation at home and abroad, and using the relative studies of concrete pavement of the highway, a preliminary interpretation of the causes of the sleeper void of twin-block ballastless track, the evolution process and influencing factors of the issues is achieved.Secondly, a coupling dynamic calculation model of sleeper-water-track slab has been established. With the help of the calculation fluid dynamics simulation software ANSYS CFX, we carry out simulation analysis on the action performances of moving water at the situation of void sleeper, which studies the general rules of hydrodynamic pressure and flow rate and changes of various conditions.And then, a hydrodynamic pressure measurement test of loose and void sleeper has been designed.Through the test we studied the existence and changing rules of hydrodynamic pressure, which were compared with theoretical calculations. The test result presents the reliability of computational theory.Finally, the scouring and fracturing action of concrete track slab in the condition of pressure and flow rate of moving water has been explored. Based on the microscopic point of view, the scouring force in concrete generated by moving flow rate, and the critical hydrodynamic pressure of scouring concrete track slab was analyzed. Also, based on the basic theory of fracture mechanics, the fracturing action of fracture in the track slab caused by hydrodynamic pressure, in the worst case, is analyzed.