Analysis On The Parameter Influences And Research On The Improvement Measures Of Track Slab Upwarp Of Double-block Ballastless Track

In recent years, some questions which influence the global stability of track are coming into being with the ballastless track put into operation. According to the findings for the service conditions of a few passenger transportation railway lines recently, track slab upwarp of double-block ballastless track is one of patterns of manifestation to the total stability of track, especially in transition section and post-cast strip of railway track. Therefore, it is of great and practical significance to conduct a research on the question of track slab upwarp. In this paper, CRTS double-block ballastless track is considered as the research object based on the field investigation to analyze the causes of slab track upwarp, and to conduct model tests of force transfer parameters between slab track and supporting course. Besides, analyzing models of double-block ballastless track in transition section and post-cast strip are established, which are used to analyze parameter influences of slab track and to research preventive measures and improvement measures of track slab upwarp.First, by field investigation of ballastless track service conditions, combining existing research achievement about structure deformation and force transfer character at home and abroad, preliminary analysis for the causes of slab track upwarp of double-block ballastless track in transition section and post-cast strip are conducted.Second, model tests of force transfer parameters between slab track and supporting course are conducted. The results of bonding strength and friction coefficient in the tests indicate that (1) discreteness of bonding strength is biggish, which is relevant to both materials and section dispose, and the value of bonding strength ranges from0.6MPa to1.5MPa,(2) the value of friction coefficient is above1.0if the contact surface after the bonding condition is destroyed. Due to the causes of material strength and friction evenness, discreteness of friction coefficient is biggish, and its value ranges from1.5to3.0.Again, analyzing models of double-block ballastless track in transition section and post-cast strip are established, and then parameter influences of slab track upwarp are analyzed. The analyzing results manifest that (1) the increase in the total temperature and temperature gradient of slab track will augment the value of it’s upwarp,(2) the increase in the bonding strength and friction coefficient could reduce the value of slab track upwarp,(3) increasing the number of anchored girder could decrease the value of slab track upwarp. Then the preventive measures of slab track upwarp are put forward.Last, improvement measures of slab track upwarp of double-block ballastless track in transition section and post-cast strip are researched, and the improvement measures are as follow: second level steels sized M25×400are as anchor pin in the measures, which are arranged between sleepers, In transition section,6ranks of anchor pin are arranged on the bridge side of anchored girder, the distance between ranks is equal to the distance between fastenings, there are4anchor pin per row.16ranks of anchor pin are arranged on the roadbed side of anchored girder ranging from0to10m, the distance between ranks is equal to the distance between fastenings, there are5anchor pin per row.10ranks of anchor pin are arranged on the roadbed side of anchored girder ranging from10m to18m, the distance between ranks is equal to the distance between fastenings, there are4anchor pin per row. In post-cast strip,4ranks of anchor pin are arranged on the both sides of after-pouring section respectively, the distance between ranks is equal to the distance between fastenings, there are4anchor pin per row.