Study On The Stability Of Continuous Welded Rail(CWR) Under Vehicle Loads And Temperature Force

With the development of high-speed and high-haul railway lines, the continuous welded rail (CWR) has been used in many countries. Since the rail is constrained and can't move freely, it would produce a high longitudinal force which could lead to railway structure's buckling as well as vehicle's derailment and do harm to the safety operation as the temperature varies.Through in-depth analysis of CWR buckling mechanism and its influencing factor, and according to the nonlinear finite element theory, the FEM model to analyze the stability of CWR track is developed. The FEM model is a track framework that includes rails, ties, rail fastenings and ballast resistances as a whole system. It can consider the nonlinear deformation of rail, ballast nonlinear resistance and rail fastenings nonlinear resistance moment. By using this model, influences of curve radius, initial irregularity, rigidity of rail, torsion resistances of rail fastenings, lateral ballast resistance and longitudinal ballast resistance on the stability of continuously welds rail track are calculated and its laws and characteristics have been found. In addition, the change in the state of stress in the ballast caused by vehicle force on the stability of continuously welds rail track has also been discussed and its laws are investigated due to changes in Train Centre Spacing, Bogie Centre Spacing and Axle Load, etc.Results show that the axial temperature force due to temperature rise is the root cause of losing stability in CWR and the initial track irregularity is the direct reason. Lateral ballast resistance is the main factors of guaranteeing stability in CWR. The track framework stiffness composed by the lateral stiffness of rail and the torsion resistances of rail fastenings is another important factor of resisting track's buckling. The longitudinal ballast resistance has little effect on the stability of CWR track, but has significant influence on the distribution of axial temperature force in rail. The invalid ties as well as the track uplift under Vehicle loads in the initial irregularity region have notability impact on the stability of CWR. With differences in the relative position between vehicle and initial irregularity of CWR, Train Centre Spacing, Bogie Centre Spacing and Axle Load, the effects of vehicle loads have different rules, which are also relevant to the rail vertical bending stiffness, ballast vertical stiffness and sleeper - ballast friction coefficient and other factors, on the stability of CWR.In a word, through analyzing the track structure's buckling from various angles, this dissertation would make valuable contributions to actual railway track's design and maintenance.