Design Research On The Terminal Spine Of CRTS Ⅱ Slab Track On The Short Subgrade Section

CRTS Ⅱ slab track is one of the main track structure types used in high-speed railway in China at present. Its longitudinal multilayer continuous structure makes the longitudinal interaction force system more complex. The longitudinal force transmission terminal spine system behind abutment is used as the limit structure of the track structure, which is an important part of CRTS Ⅱ slab track.Taking the inverted T-shaped main terminal spine as an example, this paper considers the effect of ballastless continuous weld rail on the terminal spine force and deformation behind abutment; Sets up the integration finite element analysis model of rail-slab-bridge-terminal spine-subgrade, the force and deformation of the terminal spine under temperature load or braking load and breaking slab load are calculated and analysed; Combined with the existing setting projects of terminal spine applied on short subgrade section, the analysis of the interaction between the terminal spine and the ballastless continuous weld rail is made, by optimization of existing projects, a project of foundation plate being laid continuously on the short subgrade, setting T-shaped terminal spine in the middle of foundation plate and using AB group filling material filling the terminal spine is put forward. The main research results are as follows:(1)Under temperature load, the force and displacement of the terminal spine is about 10～20 times of that under braking load, therefore, the temperature load is the main force of the terminal spine, and the influence of the braking load on the force and deformation of the terminal spine can be neglected; The position of the breaking slab force has great influence on the force and displacement of the terminal spine, and the most unfavorable position is in the position of main terminal spine, so recommends checking the breaking slab force as a accidental load separately;(2)The main terminal spine force is mainly affected by the expansion stiffness and temperature difference of the track plate and the foundation plate, according to the existing setting conditions of the inverted T-shaped terminal spine, it is only applicable to the temperature difference under 40℃ of the track plate and the foundation plate; When the temperature difference is 50℃, the longitudinal displacement of the main terminal spine reaches 4.67mm, which is already more than 3mm, and at this time, the maximum tensile stress of the main terminal spine is 2.66MPa, which is beyond the strength of concrete;(3) The force of the concretion-point of the main terminal spine and friction plate and the toe of the main terminal spine is large, which is a weak link of the main terminal spine, so suggests strengthening structure design of the concretion-point;(4) When foundation plate is laid continuously on the short subgrade and sets terminal spine, rail longitudinal force and displacement on the right side of continuous beam and the middle of the subgrade change more smoothly and the numerical value is small, which means the track structure is stronger in the longitudinal direction and it is more likely to play the role of longitudinal force transmission of the friction plate and the terminal spine; From the point of reducing the engineering cost, the economic application and ensuring the safety of project, it is available to adopt the project of foundation plate being laid continuously on the short subgrade, setting T-shaped terminal spine in the middle of foundation plate and using AB group filling material filling the terminal spine.