Research On Mechanical Characteristics Of Ballastless Track Continuous Welded Rail On Bridges In Small Radius Curve Sections Of Urban Rail Transit

As a line laying method of subway,urban rail transit viaduct has been widely used in subway construction in China and abroad due to its strong adaptability to line type,low cost and fast construction speed.Due to the restrictions of passing through blocks,crossing municipal roads,existing buildings and underground pipelines,there are many small radius curves in urban rail transit,and it is inevitable that there are small radii on elevated lines.When the train runs on the small radius curved bridge,it will not only generate longitudinal additional force due to the interaction between beam and rail,but also exert lateral force on the track structure and produce large lateral displacement,which makes the force of the track structure more complex.Based on the research status of CWR on bridges at home and abroad,aiming at the unit slab track and steel spring floating slab track on bridges,this paper establishes the calculation model of beam-slab-rail interaction in small radius curve section.The force,deformation and distribution law of the ballastless track CWR on the bridge in the radius curve section,as well as the broken bending deformation of the ballastless track are analyzed and studied comprehensively.1.The spatial coupling model of ballastless track CWR on bridge in small radius curve section is established.According to the structural composition and characteristics of unit slab track and steel spring floating slab track CWR on the bridge,based on the interaction principle of beam-slab-track and finite element method,the multi-span simply supported beam bridge and the long-span continuous beam bridge are considered respectively.The finite element software ANSYS is used to establish the spatial entity refined finite element calculation model of the unit slab track and the steel spring floating slab track CWR on the bridge in the small radius curve section.2.The mechanical characteristics of unit slab track CWR in elevated small radius curve section are studied.For the unit slab track,the distribution laws of force and deformation of CWR on multi-span simply supported beam bridge and long-span continuous beam bridge in small radius curve section under temperature load,train load,train braking load and track breaking conditions are analyzed respectively.The influence of different curve radius on mechanical properties of CWR is studied.On this basis,the rail strength is checked and calculated,which provides reference for the design and checking method of CWR on small radius curve bridge.3.The mechanical characteristics of steel spring floating slab track CWR in elevated small radius curve section are studied.For the steel spring floating slab track,three different floating slab layout schemes are considered,and their effects on the force and deformation of CWR on the multi-span simply supported beam bridge and the large-span continuous beam bridge in the small radius curve section are analyzed respectively.The results are compared with the calculation results of unit slab track CWR on the bridge.4.The influence of some key factors on the rail bending deformation of ballastless track CWR is studied.Taking the long-span continuous beam bridge as the research object,comprehensively considering the unfavorable factors of rail broken bending.The influences of initial rail bending,curve radius,overall lateral stiffness of fasteners,local failure of fasteners,overall lateral stiffness of steel springs and local failure of steel springs on the broken bending deformation of ballastless track rail are analyzed respectively.It is of great significance to improve the smoothness of ballastless track and ensure traffic safety.