Mechanics Analysis Of Ballastless Track Structure Under Heavy-haul Vehicle Loads

With the increase of train axle loads and railway transportation demand, although the operation department has enhanced the structural strength of ballasted track, the inherent flaws of ballasted track have become increasingly apparent. As a novel railway track structure, non-ballasted track, which could overcome many defects of the ballasted track, has been widely used in the high-speed railways and becomes an important development direction of heavy haul railway tracks. It has been on the agenda of many countries around the world to develop non-ballasted track for heavy-haul transport operation. Chinese Ministry of Railways has proposed to use dual blocks track and low vibration track in the tunnel of new heavy haul railway lines. At present, mastering the non-ballasted track technology, China is vigorously developing heavy haul railway with axle load more than25t. It is significant both in the aspects of theory and engineering to research the structural mechanics on heavy haul non-ballasted track.After a brief literature review of relative research work on the heavy haul train and non-ballasted track, the finite element method was applied to establish numerical models of variety kinds of non-ballasted tracks for static analysis in this thesis. Giving the static load types and parameters to evaluate the structural performance, the static responses of non-ballasted track models under different axle load were analyzed. Numerical results show that these types of non-ballasted track structures can meet the basic strength requirements to run heavy haul trains. In a sense, non-ballasted track that has elastic support has advantages than the others. Based on the vehicle-track coupled dynamics, a vertical dynamic model was established considering the characteristics of heavy haul train. Dynamic responses inducing by vehicles running on different rack structures were calculated. At the same time, the sensitivity analysis of the non-blasted track design parameter was carried out. Results show that non-ballasted track structure can meet the basic requirements for large axle heavy haul trains. Finally, the finite element models of non-ballasted tracks for structural dynamic analysis were established. The dynamical vibration responses under different conditions were calculated. The results show that when the heavy haul trains run on the non-ballasted track, the vibration response of the track structures does not exceed the limit proposed in relative design codes. Dynamic load on mortar layer increased significantly and the mortar layer is the weak link of the track structure.Static and dynamic applicability analyses of non-ballasted tracks used in heavy-haul railway were conducted in this thesis. Relevant research results could be the reference for the design and application of non-ballasted track used in the heavy-haul railway lines.