Mechanism Analysis And Repair Of Longitudinal Track Bed Diseases

The cracks in the track bed and the debonding are the main damage types of the ballastless track structure,which seriously affects the work performance of the track.At present,the ballastless track repair process pays more attention to the repair results,but lacks consideration of the disease mechanism,which causes aimless maintenance.It may affect the repair effect and worsen the track performance.The longitudinal monolithic track bed on a curved bridge of a metro operation line is seriously damaged,mainly including the Eight-shaped cracks,splitting and sloshing of the track bed.The three types of diseases are substantially the cracks in the track bed and the debonding between the slabs.In order to determine the formation mechanism of track diseases accurately,considering the time-efficiency and safety of the track disease repair in the metro operation line,and completing the disease repair work quickly and effectively,the track disease condition of this section is analyzed,tested and optimized through field investigation.A combination of research methods was used.The main research contents and conclusions are as follows:(1)The track diseases were investigated,the track geometry and the track slab dynamic test were conducted,and it was found that the Eight-shaped cracks,the upper surface splitting and sloshing of the track slab,were the three main diseases.(2)Through comprehensive coMParison,the finite element model that can reflect the main characteristics of the disease is established,and the influence of load combination such as train load,wind load and wheel-rail creep force is studied.It is found that the lateral force of the wheel and rail is too large,resulting in the concrete cracking on the surface of the track bed to form a figure-shaped crack.After the Eight-shaped crack is transversely penetrated on the surface of the track bed slab,it is affected by the crack fracture strength factor and the unilateral splitting occurs under small shear stress.Under the influence of transverse bending moment and water invasion,interlayer gap appears between the slabs.The sloshing phenomenon of the track bed is formed when the gap develops into a void.(3)According to the characteristics of disease,emergency repair and construction were carried out in typical areas of disease by setting up force transfer rod,grouting debonding,setting limit block,structural recovery,planting reinforcement and waterproof layer,etc.According to the results of the observation,suggestions for further optimization of repair methods were put forward to provide reference for the treatment of subsequent types of diseases.