| In recent years,with the continuous encryption of high-speed railway networks,the situation of parallel and cross-construction of new lines adjacent to existing lines is increasing day by day.In addition,due to the influence of various factors such as the geological environment,the uneven settlement of existing bridge piers in the transverse direction is increasing.Based on the bottom-up mapping transfer mechanism of the rail-bridge structure,the track structure laid on the beam is also deformed by the settlement of the pier,which in turn affects the geometry of the track structure.When the train runs to the settlement section,the rail surface irregularity will aggravate the wheel-rail contact vibration response,which will threaten the safety of the line operation.To solve this problem,this paper selects the standard box girder of a 32.6 m high-speed railway as the research object and establishes a static and dynamic damage coupling model considering the uneven settlement of the transverse bridge.The static rail surface deformation and inter-layer force under the action of transverse bridge settlement are studied,and the influence of settlement on driving safety and comfort is further analyzed.The main research work is as follows :(1)Based on the finite element method,the spatial static coupling model of CRTS Ⅲ unit slab ballastless track-bridge considering the transverse uneven settlement of the pier is established.Based on the theory of rigid-flexible coupling and vehicle-track-bridge interaction,the dynamic model of a high-speed train-track-bridge system is established by using ABAQUS finite element and multi-body dynamics software SIMPACK.The error is within the allowable range,which verifies the rationality and correctness of the model.(2)Considering the two settlement types of single and double piers,the settlement damage model of the ballastless track-bridge pier is established to study the influence of uneven settlement of transverse bridge piers on the inter-layer stress of CRTS Ⅲ track structure and the deformation law of track surface.The research shows that the settlement of single and double piers leads to composite irregularity such as arching,height,level,and distortion on the rail surface.When the settlement difference is the same,the settlement damage of the double pier is more serious than that of the single pier,and the settlement of the double side is more serious than that of the single side.It is suggested that the daily maintenance of high-speed railway bridges should be controlled within 10 mm,and the adverse conditions of settlement of 15 mm and above should be avoided as far as possible.(3)Based on the dynamic model of the train-track-bridge rigid-flexible coupling system,the influence of different settlement types on the safety and comfort of train operation is studied.The research shows that the wheel load reduction rate and the vertical acceleration of the vehicle body are sensitive to the influence of settlement and vehicle speed.When the settlement is too large or the vehicle speed is too high,it is easy to exceed the limit.Aiming at the high-speed railway line with an operating speed of 300 km/h,based on the train operation safety index,the single and bilateral settlement threshold of the pier transverse bridge direction are 10.98 mm and 10.7mm respectively.For the high-speed railway line with an operating speed of 350 km/h,the settlement threshold of single and bilateral piers in the transverse bridge direction is 7.5mm and 6.9 mm respectively.(4)Considering the static and dynamic evaluation indexes of high-speed railway lines and bridges,the damage classification and maintenance suggestions of a 32.6m multi-span simply supported beam bridge under the uneven settlement of single and double pier transverse bridges are preliminarily put forward.It is expected that the above classification standards can provide the theoretical basis for the " scientific repair,precise repair,and graded repair " of the public works department. |
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