Performance of Polyurethane Polymer in the Transition Zones of Ballasted and Ballastless Track

Abstract

Track disease significantly increased in the transition zones between ballasted and ballastless track. It is triggered by abrupt variation in the track’s vertical stiffness due to different support conditions. To achieve the transition of track stiffness, the ballast bed with polyurethane polymer scheme was proposed. In this scheme, the changed of ballast bed stiffness change quantity was decided by the bonding area of ballast bed with polyurethane polymer. In the test section, three bond forms of ballast bed were adopted—full bonding section, partial bonding section and local bonding section. The field test results were as follows: the vertical stiffness of ballast bed with polyurethane polymer was increased more than 5 times, 3 times, 2 times. The vertical and horizontal resistance of ballast bed was increased more than 8 times, 4 times, 3 times. With the increase of track stiffness, the vertical force of wheel-rail and the vertical vibration of rail increase, the vertical displacement of rail reduce, the vertical displacement and vertical vibration of sleeper reduce. Merely citing the vertical displacement of rail as typical, it was reduced by 25%, 16%, 3%. After the static and dynamic test, we can conclude that performance of polyurethane polymer in the transition zones can achieve the transition of ballast bed from low stiffness to high stiffness.