Influence Of Temperature Loads And Viaduct Foundation Deformation On Track Deformation Of Medium-Low Speed Maglev Transport

With the diversified development of urban rail transit systems,medium and low speed maglev transportation technology is increasingly attracting attention from the engineering community.The medium and low speed maglev track adopts a multi-layer combined structure.It must maintain the structure stability while satisfying the transmission and bearing functions.In addition,the operation of medium and low speed maglev trains has very strict requirements on the deformation limit of the track structure.Therefore,it is very necessary to carry out research on the structure and foundation deformation of medium and low speed maglev tracks.After introducing the structures and characteristics of three typical medium and low speed maglev tracks,the finite element method is used to establish the medium and low speed maglev track model including the expansion joints and bolt components.Based on the theory of temperature effect,the deformation and stress characteristics of the medium and low-speed maglev track beam and its key components are studied under extreme temperature load and vehicle loads.And it is also analyzed that the influence of the foundation deformation on the geometry of the F-shaped rail.Firstly,using the finite element model of medium and low speed maglev track,the temperature deformation and stress of the track structure are analyzed under the effects of sunshine temperature difference,sudden temperature drop and annual temperature change in Urumqi region.Result shows that,the effect of sunlight-temperature difference load on the deflection and stress of the track beam is significant.When the track structure is not taken into account,the deformation of the mid-span track beam under extreme temperature conditions is out of tolerance,but this value meets the specification requirements when considering the track structure.The annual temperature change loads will cause large longitudinal deformation of the track structure,and the sudden temperature drop will have less effect on the deformation of the track structure.Under different temperature loads,the stresses of the F-shaped rails,Hshaped sleepers and bolt-connectors are all less than the permissible limits of the materials and meet the strength design requirements of the structures.Then,taking the vertical sunlight-temperature difference load in Urumqi region as an example,the deformation and stress characteristics of different parts of the track structure under the effect of temperature and vehicle loads are studied.Result shows that,considering the joint action of vertical sunshine temperature difference and vehicle load,under normal suspended load conditions,the vertical displacement differences of the lateral magnetic pole inside and outside the F-shaped rails meet the specified limit,but the vertical displacement differences are more than the specified 0.5mm under the action of more than 1.3 times the suspension loads.In addition,under the influence of vertical sunlight-temperature difference load and different vehicle design loads,the stress of each key component of the track structure meets the structural strength design requirements.Finally,according to five different forms of bridge foundation deformation,the effect of deformation amplitude and bridge span on the geometry of F-shaped rails surface was studied.Result shows that,the deformation of F-shaped rail will increase with the increase of foundation deformation amplitude,and the length of deformation area of F-shaped rail will increase with the increase of bridge span.