Influences Of Pier Settlement And Beam Creep Of High Speed Railway On Mechanical Properties Of Ballastless Track On Bridge

The rapid development of high-speed railway has greatly promoted the progress of national economy.At the same time,with the continuous improvement of train operation speed,the service status and deterioration of high-speed railway infrastructure began to appear gradually.Under the action of long-term cyclic loads of trains and shrinkage and creep of concrete bridges,many diseases such as pier settlement and beam structure deformation will inevitably occur.The settlement of pier and the deformation of beam structure will lead to large deformation of the upper track structure until it is destroyed,and ultimately threaten the safety of train operation.In this paper,the ballastless track on the bridge under the action of pier settlement and beam creep of high-speed railway is taken as the research object.Static and dynamic analysis models are established by finite element software ABAQUS.The effects of pier settlement,beam creep,combined effect of pier settlement and beam creep on the static and dynamic characteristics of ballastless track are studied.The main research work is as follows:(1)The static characteristics of ballastless track under pier settlement are analyzed.Based on the vehicle-track interaction theory,the ballastless track-bridge coupling static model is established.Rail is modeled by beam elements,the track is modeled by solid elements,and the prestressing reinforcement is considered according to the actual situation.The bridge is modeled by solid elements,and the bridge support is considered as spring damping element.At the same time,the concrete material in the track structure is considered as non-linear.Based on this static model,the static characteristics of two types of ballastless track structures under three settlement conditionss,such as single pier settlement,two adjacent piers settlement and two non-adjacent piers settlement,are studied,and the effects of different settlement amplitudes on the static characteristics of ballastless track are analyzed.The results show that for CRTS I slab ballastless track,the tension and compression stresses of track slab are more affected by settlement amplitude than those of CA mortar and base slab,and the tension and compression stresses of track slab are the largest under two non-adjacent piers settlement.For CRTS II slab ballastless track,plastic damage will occur along with the increase of settlement amplitude under three settlement conditions,and the settlement of two non-adjacent piers is the most disadvantageous to the stress of CRTS ? slab ballastless track.(2)The static characteristics of ballastless track under beam creep are analyzed.Based on the ballastless track-bridge coupling static model,the static characteristics of two types of ballastless track structures with different creep amplitudes are studied.The results show that the beam creep will lead to periodic arch deformation of two types of ballastless track structures,and the deformation curve of CRTS ? slab ballastless track is more smooth.When the creep amplitude is between 5mm and 30mm,track slab and base slab of CRTS ? slab ballastless will appear plastic damage with the increase of creep amplitude,and the base slab is more sensitive to the creep deformation of the beam,and plastic damage will occur when the creep amplitude is smaller;CRTS ? slab ballastless track structure has never been plastic damage.(3)Static characteristics of ballastless track under combined effect of pier settlement and beam creep are analyzed.The static characteristics of two types of ballastless track system under combined effects are analyzed under different settlement amplitudes of piers and creep amplitudes of beam.The results show that the combined effect of pier settlement and beam creep increases the rail deformation of two types of ballastless track in the area affected by combined effect.The tensile damage value of track slab and base slab of CRTS ? slab ballastless track under combined effects is larger than that of beam creep.For CRTS ?slab ballastless track,the combined effect of pier settlement and beam creep eliminates the track plastic damage caused by the settlement of single pier.(4)The dynamic response of vehicle-track-bridge system under the condition of pier settlement and beam creep is analyzed.Based on the vehicle-track-bridge interaction theory,the vehicle-ballastless track-bridge coupling dynamic model is established.The vehicle model is considered as a multi-rigid-body coupling system,and the rail is modeled by solid elements.The vehicle model and ballastless track model are connected by wheel-rail contact model,and the influence of track irregularity is considered.Based on this dynamic model,the effects of derailment coefficient,wheel load reduction,vertical acceleration and lateral acceleration of vehicle body with different amplitude of settlement and creep are studied.The results show that pier settlement and beam creep have a greater impact on derailment coefficient,wheel load reduction and vertical acceleration of vehicle body,but a smaller impact on lateral acceleration of vehicle body.The wheel load reduction and vertical acceleration of vehicle body will exceed the corresponding safety and comfort limits with the increase of settlement and creep amplitude.At the same time,based on the evaluation criteria of vehicle safety and comfort,the corresponding settlement and creep thresholds of two ballastless track systems on bridge under the action of pier settlement,beam creep and combined effect are given.