| With the full completion of ’’ Four vertical and four horizontal ’’ and the encryption and formation of ’’ Eight vertical and eight horizontal ’’,the research of high-speed railway in China has gradually transformed from large-scale construction to infrastructure maintenance,line optimization management and train safety operation.Influenced by geographical conditions,complex environment and other factors,bridge structure has been widely used in high-speed railway.China is a country located in multiple seismic fault and large subsidence areas.In this case,the pier settlement in high-speed railway is very common.When the pier settlement occurs,it will directly lead to the change of the geometry of the ballastless track and the interlayer contact state,which will affect the dynamic characteristics of the train and threaten the train operation safety.In addition,the train speed limit caused by pier settlement has accounted for 40% to 50% of the reasons for the speed limit of high-speed rail in China,which seriously restricts the speed of high-speed rail.Therefore,the typical unit slab and longitudinal slab ballastless track-simply supported beam bridge system in China is selected as the research object.On the basis of summarizing,digesting and absorbing the previous research results,the main research contents and conclusions are as follows:(1)Based on Castigliano’s second theorem and Linear superposition principle,a rail surface analytical characterization model of ballastless track-bridge system is established considering the influence of the existing interlayer stiffness mutation,the unknown interlayer stiffness mutation,and the limit components of ballastless track.The parametric solution of the model is realized by MATLAB programming.Finally,the analytical solution of the characterization model is compared with the experimental results,the measured results and the simulation results,which fully demonstrates the correctness and effectiveness of the characterization analytical model.(2)Based on the verified analytical mapping model of rail surface,the influence of pier settlement amplitude,interlayer stiffness mutation and limit components on rail surface deformation is quantitatively studied,and the influence degree of the above factors on the rail surface deformation of ballastless track with different slab types and different positions is calculated and analyzed.With the increase of pier settlement amplitude,the deformation of two kinds of slab ballastless track increases gradually.The influence of mortar void on rail surface deformation is several times higher than that of other interlayer stiffness mutation types.Compared with the existing interlayer stiffness mutation of track,such as fastener breaking,mortar debonding and mortar void,the influence of the limit components on the rail surface deformation is very weak.(3)On the basis of expounding the formation mechanism of the unknown interlayer stiffness mutation of the two kinds of slab ballastless track under the pier settlemen,the proposed mapping model is used to study the variation law of the interlayer contact behavior of the ballastless track,the development law of the interlayer contact behavior of track with the settlement amplitude and mileage is analyzed,and the influence mechanism of different positions and lengths of fastener breaking and mortar void on the contact behavior is revealed.For the unit slab ballastless track,the mortar debonding first occurs in the settlement pier area.For the longitudinal slab ballastless track,the void beneath the slab first appears in the left area of the adjacent pier of the settlement pier.In the actual project,the mortar debonding is not easy to appear,and the void beneath the slab between the base slab and the bridge deck should be focused on.(4)A coupled dynamic model of train-track-bridge system considering pier settlement and interlayer connection failure is established and verified by literature results.On this basis,the influence of interlayer connection failure and pier settlement amplitude on the dynamic response of two kinds of slab ballastless track is studied,the dynamic mapping relationship between pier settlement and train dynamic response considering interlayer connection failure is proposed,and the safety threshold of pier settlement of high-speed railway is determined.When considering the interlayer connection failure,the influence of the interlayer connection failure of the unit slab ballastless track on the dynamic response index is very weak,and the maximum value of each dynamic index of the longitudinal slab ballastless track is about 2times that of the unconsidered.According to the safety requirements of high-speed train operation,the settlement safety threshold of unit slab ballastless track pier is 25.19 mm,while that of longitudinal slab ballastless track is 22.47 mm. |
