Research On Distribution And Homogenization Of Track Stiffness In#12Heavy Haul Turnout

Modern railway transportation became highly division-clear and specialized bothin high-speed railway and heavy haul traffic. The demands which ensure themfunctioning well are much different. As to heavy haul railway, besides safety andgeometrical stability, life expectancy and technique economics are considered intop-priority.Through in-depth literature review of development of turnouts and research intrack stiffness, it appears that despite that all the effort has been proceeding, verticalstiffness variations along the track, namely, track stiffness irregularities are emergedto be a serious problem. Railway vertical track stiffness is a essential parameter whichinfluences the bearing capacity, geometrical stability and the life of track components.Changes in track stiffness will cause variations in the rail-wheel interaction forces,which may incur vibrations of train and track components leading to fatigue problems,cracks, wear, plastic deformation and so on.To achieve the purpose that it is qualified to use in the heavy haul traffic,structure redesign and improvement of materials are commonly used and take intoeffect in the new-designed75-12heavy-haul turnout. Field dynamic testing has beenconducted in Da-qin railway and excellent service performance has been proven. Forfurther improvement, a study raised in the track stiffness of heavy-haul turnout.Though what have done in track stiffness of high-speed turnout is coming into use,apparently far from sufficient and complete, less work has been done within heavyhaul track yet.The three-dimensional finite-element numerical model of new-designed turnout isestablished. Using that model, the calculation of turnout stiffness distribution has beenproceeded and influences of vertical stiffness to turnout is analyzed, including themilling of switch rail, setting of smooth bed, using of spacer block and so on. Aswitch contains several irregularities in stiffness. The bending stiffness of switch railand point rail differs from section to section; the lengths of sleepers are incrementalalong the track and so on. Smoothing track stiffness irregularities of turnouts is moredifficult than that in common line. After deliberate consideration of optimization intheory and engineering feasibility, tie plate grading arrangement is recommended as abest method among all the engineering proposals, and integrated layout plan has beenraised and fully presented.