The Research Of High Speed Railway Bridges Track Deformation Under Earthquake

High speed railway is with the high density of traffic flow, traffic, fast speed, etc. High-speed railway bridge seismic design is not only to ensure the safety of the bridge structure, but also to ensure a certain degree of operational safety during an earthquake. In addition, the wheels in direct contact with the tracks and track state directly affect the operation of the train. Under the seismic action, such as bending, deflection track deformation, vibration amplitude caused by the earthquake, may make the driving train derailment. In order to make train safety analysis under the action of earthquake, this article mainly studies the aspects of rail deformation.In this paper, we focus on 5 span simply supported girder bridge near bridge-subgrade transition as the research object. Study the relationship between main girder deformation and rail deformation and the influence of factors pier stiffness, fastener stiffness, support form on the orbit deformation Finally, according to urban rail seismic design specifications of the traffic safety limits, under different seismic fortification intensity E1, make a evaluation of high-speed railway bridges of paralleling angular, turning angle and dislocation. The following is the main work and related conclusions:(1) In this paper* the refinement model set up, then simplify the refinement model and get small computational cost, finally, the simplified model can satisfy the engineering precision.(2) Study the track constraint effect on the earthquake response of the high-speed railway bridge girders.The results show that track constraint function of high speed railway Bridges have effects on displacement of girder, the more far away from the roadbed, restriction in rail system is weak, and close to the unconstrained. Horizontal or longitudinal seismic response based on the analysis of main girder, the influence of vertical ground motion can ignored with the presence of track, only consider the condition of the ground motion along the longitudinal and transverse one-way input.(3) Study the track lateral deformation of the main beam joints distribution are.Results show that the deformation of beam joints of fasteners is bigger, to the fourth fasteners, its deformation is close to zero, So track deformation area caused by beam joint dislocation is around four fasteners at beam joint; And nearest the beam end the fastener deformation value is the biggest, beside, track lateral deformation most concentrated in this area.so analysis track angular, which calculation can base on the rail surface relative displacement of two fasteners around beam joints.(4) Study the relationship between the deformation of main girder and track deformation,which will provide the basis to follow-up study of the subject by controlling the seismic response of the main girder to ensure the traffic safety of the train. The results show that deformation of rail surface attachment beam of dislocation, a numerical relationship is between whom; Fasteners spacing of 0.6 m to beam joints as analysis scope, level of rail surface relative displacement in the horizontal dislocation displacement of beam body changes between 40%～55%, the rail surface vertical relative displacement in the vertical faulting displacement of beam body changes between 25%-40%.(5) Study the influence of pier stiffness change to the track angle. The results show that When the pier is the same, so the stiffness, and the lateral stiffness of piers is larger, the level of track angular are generally small and the level of the relatively large angle is in abutment; With the decrease of the pier line stiffness, track level angle increased gradually. The transverse stiffness of fasteners increasing, orbital level Angle increases; When adjacent pier line stiffness variation law is consistent, track level Angle will be the same, but comparing to equal stiffness of each pier, Angle will be larger; When the stiffness of adjacent spans is same, The smaller the line rigidity, the bigger the horizontal Angle;Track vertical Angle and horizontal Angle having the same change trend, at the same position, the vertical Angle value is smaller than level to the Angle value.(6) Study the influence of fastener stiffness to main girder deformation and track deformation. Results show that the effect of the fastener stiffness to longitudinal displacement of main girder is very small, but large to the girder lateral displacement, when the stiffness fasteners is low, with the increase of fastener stiffness, the lateral displacement of main girder has larger growth trend, and when the fastener stiffness is big, to increase its stiffness, displacement of the girder would be expected to increase significantly decreased; Increase the transverse stiffness of fasteners are basically not improve orbit relative displacement on surface of the beam joints of the rail, it may make the track Angle has increasing trend.(7) Due to the high speed railway bridge piers is just, paralleling angular, turning angle are parallel to meet the requirements, besides, There is nonbridge-subgrade transition where the stagger displacement of adjacent girders meet the requirements and track deformation is small, which will not affect the safe operation of the train. Under the 8 fortification intensity, when the pier’s height is more than 5 m, some safety measures should be taken. Under the 7 (0.15g) fortification intensity, when the pier’s height is more than 15 m, some safety measures also should be taken. Under the 7 (O.lg) fortification intensity, when the pier’s height is more than 15 m, it is optimized on this structure.