Dynamic Behavior Of B70 Concrete Sleeper On Wide Gauge Ballast Track

The B70 pre-stressed concrete sleeper is mainly used in freight railways and urban public transportation lines,there is precedent for use on passenger lines in Uzbekistan.The main purpose of using pre-stressed concrete sleepers on the Tashkent-Kharshi line is to reduce the vibration of the track structure.This paper mainly focuses on whether the concrete sleeper can reduce the vibration of the track structure and study the influence of some parameter to the dynamic response of the track structure.The main research innovations of this dissertation are given as follows:(1)A vertical plane dynamic model and pre-stressed concrete sleeper solid model of concrete sleeper and type ? concrete sleeper with ballast are established.The comparative analysis shows that the pre-stressed concrete sleeper can reduce the acceleration of the rail,which is beneficial to vibration reduction;it can reduce the acceleration of the track bed,which henceforth,reduce the track bed powdering.It can also reduce the pressure on the sleeper and the pressure of the track bed,which contribute towards the reduction of stress of the sleeper,and is as well,beneficial to the reduction of long-term deformation of the track bed.However,the vertical displacement of the rail,the sleeper and the track bed increases,which is favourable to the stability of the track structure.The acceleration is smaller,which is favourable to displacement of the ballast on the track bed whilst unfavourable for the displacement of the fastener.In order to optimize the structure of the B70 pre-stressed concrete sleeper with truss track,the three influencing parameters of track bed thickness,fastener stiffness,and sleeper spacing are analysed,and a reasonable reference value is proposed.(2)When the thickness of the track bed is increased,the rigidity of each level of the track structure is reduced,and the quality of the track bed vibration is increased.The result is the displacement of the rails,sleepers and track beds,as well as the acceleration of the rails tends to increase.While the track bed vibration,the pressure between the sleepers and the track bed decreases.Therefore,the value of acceleration between various parts is decreased.So,the thickness of the track bed can be reduced to 0.4m.(3)The displacement of the rail is reduced,but acceleration is increased.Also,the increment in the fastener stiffness leads to the reduction and unevenness of the track,hence,accelerating the displacement of other components of the increased track structure.This increases is not large,so the fastener stiffness can be improved by reducing the unevenness of the rail.For balanced consideration,the fastener stiffness can be shortened to 50MN/m.(4)The reduction of the sleeper spacing is advantageous for reducing the displacement and acceleration of the rails,sleepers and track beds,as well as the pressure between the track bed and the sleepers.The displacement of the rails,sleepers and track beds will produce a valley when the spacing between the sleepers is 0.54 m and 0.58 m,which is the smallest when the sleeper spacing is 0.54 m.