Subgrade Cumulative Plastic Deformation under the Bridge in the Transitional Period of Orbit Dynamics Analysis

Abstract

In this paper, the author researches on the dynamic characteristics analysis of bridge transition track under cumulative plastic deformation of subgrade. This paper considered interaction between structural layers and, by in combination with the dynamic model of slab track and by use of finite element software, established the spatial dynamic numerical model of vehicle-track-subgrade coupling system and then analyzed the dynamic response in the bridge-subgrade transition section in the form of regular and inverted trapezoid. The results show that: Under the action of train load, the dynamic responses in the two kinds of transition section are basically consistent; The settlement of the section in inverted trapezoid is slightly larger than that of the section in regular trapezoid, while the section in regular trapezoid is more favorable to maintenance of the track regularity, in contrast to the section in inverted trapezoid; The junction between bridge and subgrade (in the range of 5 m behind the abutment) is the weak portion in the whole transition section, and should be designed and constructed separately. By considering the dynamics indices of locomotive, the track deflection angle of the transition section should set the limit value of 0.05%, K 30≥210 MPa in the range of 0~5 m behind the abutment and K 30≥150 MPa out of the range of 5 m.