Study On Fatigue Property Of The CRTSⅠ Slab Track For Mixed Passenger And Freight Railway

For China, after the acceleration of some existing railway and during the primary period of the operation of passenger dedicated line, the mode of the mixed passenger and freight railway in the same line has been widely applied in order to relieve the heavy load of railway transportation. The CRTS I prefabricated slab track has been widely applied in China for its mature structure and convenient construction. For the CRTS I prefabricated slab track of passenger and freight mixed railway, it can not only undertake huge axle load and great amount volume as heavy-load railway, but also drive intensively and travel fast. The contradiction between transportation capacity and transportation volume becomes obvious. The changing of the line load situation would accelerate the wheeltrack system power and increase the invalidation and deformation of the structural members. Therefore, the fatigue failure of the track structure within the designed and applied year would increase largely in addition of the natural effects. However, there are very few researches on the systematic fatigue characteristics of CRTS I prefabricated slab track of the mixed passenger and freight railway at home and abroad. The dissertation appears to have certain significance in theory and engineering application. The main ideas are stated as follows:(1) Based on wheel-track system dynamics and referring to ANSYS/LS-DYNA, the dissertation studies on the CRTS I prefabricated slab track. It takes CA (cement-emulsified asphalt) mortar layer connection failure into consideration and simplifies it properly. The vehicle-CRTS I prefabricated slab track vertical coupling vibration spatial model has been built. It concludes the influence disconnection has on the stability and safety of passenger and freight line and rail system vertical power.(2) The study collects and reorganizes the basic rules of anti-fatigue design. Based on typical fatigue accumulation theory, it refers to the Fatigue module of ANSYS WORKBENCH with finite-element method, and calculates the forecast life span of the CRTS I prefabricated slab track separately with parameters as concrete depressed S-N curve and concrete bending S-N curve using the method of S-N curve fatigue life span analysis. Then chooses concrete bending S-N curve as the calculate parameter of further fatigue analysis.(3) Base on the fatigue life span calculating and analyzing method of S-N curve, the research takes train load (the single effect of passenger train load and freight train load, and interacted effect of the mixed passenger train and freight train load) effect into consideration to forecast the track board life span with the help of rain-flow counting method. In addition, the research also studies the possible effect on track board fatigue life span under the circumstance of the CA mortar damages.The results show that for the CRTS I prefabricated slab track of passenger and freight mixed railway, the operationof freight train is the main factor to cause the performance deterioration and reduce the fatigue life of track structrue. Especially when the damage of CA mortar layer tends to create voids underneath the track slab, the loading environment of passenger and freight mixed transport will cause more adversely affected on the track system.