Research On The Influence Of Connection Damage And Maintenance Limit For Slab Track Of Turnout

Turnout is a is an important part of the high-speed railway track which allowing the rolling stock run from a track branch into another,realizing the cross of different lines.It's difficult to avoid producing a variety of diseases during their service,and the disease will affect the turnout structure and driving safety,the interlayer damage is the most common form of injury.In this article,the influence of mechanics and wheel-rail system dynamic performance of irregular interlayer damage between turnout slab and base of track was analyzed,and also proposed maintenance standards of interlayer damage between the slab and the base.This article is about the research on the connection damage of slab ballastless track in turnout area,including the following contents and conclusions:(1)Based on field surveys,the injury of base is divided for their own damage,the interface damage and construction defects three categories,by the analysis of damage which provide a reference to explain the cause and development mechanism of damage.The most important factor affecting the quality of the turnout base plate is construction pouring quality,if construction quality is improperly controlled,The edge of slab is easy to produce open joint,improve the quality control of construction is the basic way to maintain the long-term durability of the base plate.(2)Using the finite element method,analysis statics model for the slab turnout is established,nonlinear spring was used to simulate different height of open joint,fractal principle is used to simulate the uneven boundary of open joint,consider the train load and temperature gradient alone or coupling,and in-depth studing the influence of open joint of different type,different leght,different height to turnout structure.Studies have shown that,open joint in slab-end is most disadvantageous to the ballast structure,followed by slab-edge,then the slab-conner and the middle of slab.When the area of open joint of slab-coner exceeding 0.3m~2,the tensile stress exceeds the cracking stress of concrete slab.Open joint in the middle of the slab has little effect on the track structure.When the length of open joint of slab-end is more than 0.8m and the height is greater than 2mm,the vertical displacement and longitudinal and stress lateral tensile stress of the turnout plate increases sharply.When the distance of slab-edge exceeds 0.6m and the height exceeds 2mm,the longitudinal tensile stress of the turnout plate reaches several times of normal state and exceeds the cracking stress of the concrete of the turnout plate.(3)Based on the dynamic theory of wheel-rail system,using finite element analysis software,and in-depth studing the influence of open joint of different type,different leght,different height to turnout structure.Open joint form the track dynamic irregularity,intensify the vibration of the wheel-rail system,reducing driving comfort and safety,the open joint of slab-end is the most unfavorable effect on the track structure,when open joint is large,the track dynamic irregularity caused by open joint began to play a leading role,maximum wheel-rail vertical force,relative displacement of turnout structure,vertical vibration acceleration as well as wheel increased sharply.Under the cycle action of train load,will significantly accelerate the development of open joint and orbital components trauma,reducing driving comfort and safety.Studies have shown that,the open joint of slab-corner has little effect on the track structure,the dynamic response of ballast structure is mainly caused by the irregularity of the rail itself.When the length of open joint exceeds0.4m~0.8m,vertical vibration acceleration and relative displacement of turnout structure significantly increased,which will accelerate turnout structure trauma.When the length of open joint of slab-edge is more than 0.6m,the dynamic response of the turnout system increases sharply,affecting driving comfort and safety of the turnout.(4)Combined with the maintenance theory and characteristic of damage,maintenance level of open joint of slab-end,slab-edge,slab-corner and middle of slab are divided into grade I,garde II,grade III three levels,according to three specifications of length l,the height h and the width b.