Fatigue Analysis Of High-speed Railway Track Slab Fracture And CA Mortar Void

With the rapid development of domestic high-speed railway and large-scale construction of passenger dedicated line,CRTs I slab ballastless track is widely used in the construction of high-speed railway in China because of its mature structure and easy construction.Under the influence of high-speed train load,the main structure of slab ballastless track is difficult to avoid various diseases such as track slab rupture and CA mortar void.These diseases may affect the stress of the track and the vibration of the wheel rail system,thus affecting the long service life of the track.Therefore,it is necessary to establish the analysis model of ballastless track with defects,and study the crack propagation under the fracture of ballastless track slab and the stress characteristics under the void of CA mortar,so as to further study the fatigue life of ballastless track,which has important practical significance for the maintenance and treatment of defects in the process of track operation.The research contents and achievements of this paper are as follows:(1)Through consulting various literature and field investigation,according to the field application of slab ballastless track at home and abroad,this paper introduces the main diseases of slab ballastless track,in which track slab crack and CA mortar void are the most common diseases,analyzes the causes,and then determines the disease form to be studied in this paper.(2)The high-speed railway vehicle crtsi slab ballastless track subgrade model is established by ABAQUS finite element software,and the different void states of CA mortar are simulated by the life and death element method.The response law of CRTSI slab ballastless track system under dynamic state under different void length,void width and void position of CA mortar is briefly simulated and summarized,The results show that the end void of CA mortar has more influence on the dynamic response of track structures than the middle void.Then the concrete fatigue equation is introduced to more intuitively predict the fatigue life of track operation under different void conditions,so as to ensure the safe operation of the train.(3)Based on the fracture mechanics theory,the finite element model of CRTS I slab ballastless track is established.The model is simulated by ABAQUS,which is a finite element analysis software.The energy release rate of crack tip is obtained only under the train load,and the crack propagation is judged according to the fracture criterion of maximum energy release rate.The results show that the energy release rate at the crack tip increases first and then decreases slowly with the increase of crack depth.When the initial crack accounts for 11/20 of the thickness of the track plate,the maximum energy release rate appears at the crack tip,which has a great influence on the instability and growth of the crack.Based on the above calculation results and Paris formula of crack fatigue growth theory,the fatigue growth life of rail plate crack is studied.