Durability Study On CRTSⅡ Type Ballastless Track Slab Based On The Reliability

Ballastless track is mainly the reinforced concrete structure, in the effect of high-speedtrain, temperature and the external environment, performance of track structure willdeteriorate gradually, even injured or damaged with the accumulation of time. This papersummarizes the durability problem and research situation on durability of ballastless track ofdomestic and foreign, proposes the method of evaluating durability of ballastless track basedon the results of reliability analysis, establishs the durability failure mode mainly for fatigue,cracking and concrete carbonation, and calculates the failure reliability and probability of thethree aspects, and regard the failure reliability and probability as basis of evaluating durabilityof the ballastless track.Before the reliability analysis of the structural, the random input variables data is veryimportant for the reliability analysis results, the variables used in the analysis of structuralreliability always is the statistics of many actual experimental data that obtained throughstatistical test. The paper collected CRTSII type slab cracking moment data under static loadtest and obtained statistical characteristics, and also collected ballastless track load-timehistory thrugh simulating the vehicles running on the ballastless track established by finiteelement software, and uses the statistics of load-time history data to analyze the reliability ofballasted track.By using the finite element software ANSYS, established the static finite element modelof CRTSII type slab ballastless track, considering the actual boundary conditions, calculatedand verified the results. Then set the static finite element analysis process with parametricanalysis as reliability calculation documents. Considering the mechanism of fatigue andmechanism of failure of the track, and identifies the corresponding failure function. Andconsidering the effect of environment on durability of ballastless track, establishs thedurability failure mode of concrete carbonation based on the mechanism of carbonation. Thenuses the reliability analysis method that combined Monte-Carlo method with ANSYS toanalyze the reliability of slab, and to evaluate the durability of ballastless track based on thereliability results.The results of the reliability shows that in the coupling of train loads and temperature,fatigue strength meet the requirements, the probability of crack width gauge is small,Carbonation in orbit during the design life period is less likely to lead to durability failure.The results of analysis of parameter’s sensitive shows that the train load, fastener stiffness,the elastic modulus of track plate, steel and the support layer, temperature and the stiffness ofsubgrade have a significant impact on the reliability of the slab fatigue, temperature andthickness of concrete cover have a significant impact on the track cracking failure board, the thickness of concrete cover, concrete strength, and environmental factors have a significantimpact on the reliability of the slab carbonation durability.This paper makes a qualitative assessment of the durability of the slab based on thereliability analysis and parameter sensitivity analysis, and make decisions to the maininfluencing factors to durability of the ballastless track. It is an attempt of researching ondurability of ballastless track from the reliability perspective.