Experimental Study On Temperature Adaptability Of Ballastless Track Of Recycled Plastic Composite Sleeper

Recycled composite sleeper(hereinafter referred to as composite sleeper)is a new type of sleeper made of polymer materials,because of its good performance in vibration and noise reduction,it has been widely used in railways.However,due to the material properties of the composite sleeper,the linear expansion coefficient is large and about 10 times that of concrete.When the composite sleeper ballastless track is used,under the effect of temperature load,the two have certain influence on the geometry and structure of the track due to the different deformation amount.Therefore,it is necessary to study the influence of temperature load on the ballastless track structure of the composite sleeper.Firstly,in order to determine the linear expansion coefficient of this type of composite sleeper material,a measurement test was designed.The deformation of the test piece at each temperature was measured,and the data was fitted and derived to obtain the relationship between temperature and linear expansion coefficient.The experimental research found that the deformation of the material with temperature can be divided into low temperature section,normal temperature section and high temperature section.The linear expansion coefficient increases rapidly and decreases slightly in the low temperature section,the normal temperature section tends to be constant,and the high temperature section Increases slowly.It is not constant at temperature.Secondly,the long-sleeper buried and double-block composite sleeper ballastless track real-scale model is designed to test the gauge change and the sleeper deformation of the two tracks structures under the integrated heating and cooling,and the test results are processed and analyzed.The test results show that seam were all appeared in the two tracks under integrated cooling,and the seam value of long-sleeper buried is larger than double-block,Therefore,both structures should pay attention to the maximum cooling rate in the laying area.In the process of overall temperature change,the gauge of long-sleeper buried has a large change,and its structure should be laid in a small annual temperature difference and avoid direct sunlight,but the gauge of double-block is basically unchanged.Therefore,the double-block track can adapt to larger ambient temperature changes while reducing the amount of sleeper,and is superior to the long-sleeper buried in terms of structural stability.Then,the two finite element models of ballastless track are established,and the deformation and gauge change of the sleeper under the overall temperature and temperature gradient are calculated and compared with the test results.The results show that under the overall temperature load,the simulation results are basically equal to the experimental test results;under the temperature gradient,the gauge and the seam width of the two track structures are below the limit.Finally,according to the test temperature and the finite element calculation of the laying temperature,the temperature requirements of the two track structures under the conditions of structural stability and geometry are summarized.