| Nowadays,the speed of railways is constantly improving.It’s more convenient for people’s life,but the track vibration not only worsen the wheel-rail relationship but also shorten the life of track structure.It will leave the hidden danger for the safe operation of high-speed railway.The existing measures of rail vibration reduction mainly focus on changing the overall stiffness of the rail system,using heavy-duty rail,setting up vibration reduction fasteners and so on.Although these measures can reduce the vibration of the orbital structure,these also lead to abnormal wear of the rail and increase the investment of the rail s tructure as a result.On this basis,relevant people at home and abroad put forward some new measures to solve this problem,such as downward the vibration reduction part,increase the vibration quality of the orbit system and consider the energy consumpti on of material damping.Therefore,it’s of great practical significance to develop a new cement-based material which can be used in rail transit structure and has excellent damping performance.In this paper,the method of combining polyurethane material with excellent damping performance with cement-based material is proposed.This paper mainly studies the effect of fillers and polyurethane on cement mortar working performance,basic mechanical properties and damping performance.The influence of the vibration reduction layer of polyurethane cement mortar of different thicknesses on the dynamic characteristics of the plate-type track structure is analyzed by numerical simulation.The details are as follows :The basic mechanical and damping properties of polyurethane cement mortar.First of all,9 kinds of mix proportion of polyurethane cement mortar are designed according to different contents of polyurethane,and the consistency,the flexible and the compressive strength of polyurethane cement mortar are researched.Then 5 kinds of mix proportion are chose according to the test result,and then the elastic modulus and the damping properties are researched.The loss factor,storage modulus and loss modulus are measured by Dynamic Mechanical Analyzer.The results show that the incorporation of polyurethane can significantly reduce the consistency and the mechanical properties of mortar.The incorporation of polyurethane can increase the loss factor and loss modulus of mortar and improve the damping properties of polyurethane cement mortar.Fillers enhance damping property of polyurethane cement mortar.According to the test results of previous chapter,the polyurethane content of 10% is chose as a basic mix proportion.Then 15 kinds of mix proportion are designed to research that the effects of the the content of mica powder,crystal whiskers and the mixture of mica powder and crystal whiskers on the basic mechanical and damping properties of polyurethane cement mortar.The results show that all the 3 kinds of fillers can reduce the consistency of polyurethane cement.The crystal whiskers can improve the strength of polyurethane cement mortar.The mica powder makes a better increase effect on the loss factor than the crystal whiskers,but the crystal whiskers make a better increase effect on the storage modulus.The effect of mixed filler on the basic mechanical and damping performance of mortar is not as obvious as that of single mica powder or single doped whiskers.Build the four-layers vehicle track model and analyze the vibration reduction performance of the polyurethane cement mortar.According to the test results,the polyurethane content of 10% and the crystal whiskers of 4% are chose to the best vibration reduction material.The cost of polyurethane cement mortar is calculated,and then analyze the selection of plate track structure.The results show that the vertical peak displacement of the orbital structure is reduced 49.74% and the vertical peak acceleration is reduced 38.00%.Considering the cost of material,the 50 mm～100 mm thickness of polyurethane shock-absorbing layer is recommended.In vibration sensitive locations,it is effective to combined with other vibration reduction measures to reduce the vibration of the orbital structure and extend the service life of the orbital structure in the high-speed running state of the train. |
