Research On The Crack Initiation And Growth In The Sleepers Corner Of CRTS? Double-block Ballastless Track

In recent years,the high-speed railway in our country maintains the fast development.Ballastless track is applied in the construction of high-speed railway in most,among them,double-block ballastless track which is a main structure of ballastless track is applied widely.Double-block ballastless track bear a long-term and repeated influence of the outside temperature and train load,combined with the influence of its own structural characteristics and the material characteristics of concrete,a large number of cracks appeared on the track.The existence and growth of cracks will cause corrosion of steel bars and affect its long-term effect.Thus,it is very important to study the mechanism of crack's occurrence and development.Based on the theory of damage mechanics and fracture mechanics,this paper established a finite element model of the double-block ballastless track to study the initiation and growth of the crack on the corner of sleeper of the double-block ballastless track on the roadbed of Wuhan-Guangzhou passenger special line.To accomplish this research,the following work is required:(1)The causes of cracks on double-block ballastless track are analyzed preliminarily and the crack types are summarized.Then the crack on the corner of the sleeper is determined as the main analysis object.(2)A finite element model of double-block ballastless track with damage plasticity is established by using the finite software ABAQUS and the theory of damage mechanics.Then the characteristics of damage factor and stress under different loads are analyzed and the initiation position,initiation trend and initiation time of the crack on the corner of sleeper are analyzed.Finally it is pointed that the main cause of the crack on the corner of the sleepers is the structural characteristics of the sleepers block and the effect of external temperature load.(3)Based on the theory of fracture mechanics,the finite element model of double-block ballastless track with crack is established and the characteristics of stress intensity factors(SIF)of crack tip under different loads are analyzed.Then this paper studies the growth law and the instability growth state of crack on the corner of sleeper and analyzes the factors that affect the crack on the corner of sleeper.Finally,the axial temperature load is determined as the main driving force during the crack growth on the corner of the sleeper.