Study On The Influence Of Stiffness Of Rail Pad On The Impact Fatigue Characteristics Of CRTS? Slab Track

CRTS ? slab track is one of the main track structure types of high-speed railway in China.Under the influence of wheel rail force and environmental factors,fatigue damage and component aging have occurred,especially the stiffness of rail pad in fastening system will increase with the extension of operation time.This will not only lead to the increase of wheel-rail impact,but also aggravate the fatigue damage of track structure.Therefore,it is necessary to study the fatigue damage mechanism of track structure under wheel-rail impact and evaluate the effect of rail pad stiffness on fatigue life.In this paper,CRTS ? slab track structure is taken as the research object,the dynamic stress and fatigue characteristics of track structure under wheel-rail impact are analyzed,and the influence of the stiffness of rail pad on the service life of track structure is discussed.Firstly,the multi-body dynamic model of CRTS ? slab track is established to analyze the wheel-rail interaction under track irregularity,and the influence of rail pad stiffness on track dynamic action is analyzed.Under different track irregularities,the maximum vertical force of wheel and rail increases with the increase of rail pad stiffness,but the growth rate slows down gradually.The main factors that increase the maximum vertical force of wheel and rail with the increase of rail pad stiffness are random long wave irregularity of track,and the vertical force of wheel and rail caused by harmonic short wave irregularity is not to do with rail pad stiffness.Next,the transient analysis model of CRTS ? slab track is established,which has the ability to solve the deformation and stress of each component of track structure under dynamic loads.According to the calculation results,it is predicted that the failure mode of track slab is crushing at the bearing platform,while CA mortar is cracking at the end of the slab and falling at the corner.When the track system has harmonic short-wave irregularity at the same time,the influence of the stiffness of rail pad on the dynamic stress amplitude of track structure is significantly higher than that of track with only random long-wave irregularity.Finally,the typical fatigue damage model of concrete and CA mortar material is applied to CRTS ? slab track structure to predict the fatigue life of track structure under wheel-rail impact load when the stiffness of rail pad is different.The fatigue life of track slab can fully meet the fatigue performance requirements under various track irregularities and rail pad stiffness conditions.When the track system has harmonic irregularities,fatigue life of CA mortar layer decrease exponentially with the increasement of rail pad stiffness.The fatigue life of track slab can be determined on the premise of ensuring the safety of track structure and low maintenance workload.The optimal solution is 14 years,and the static stiffness of the rail pad is 67.2 kN/mm.