Tack Static Irregularity Management Value Research For Subway Viaduct Line Based On Virtual Track Inspection Method

Track static irregularity,as exciting source of wheel-rail system,is a key factor affecting train operation quality.However,there is currently a temporary lack of relevant regulations for the subway static irregularity management,and “the Regular-speed Railway Lines Repair Codes” are mostly used to guide the maintenance subway line.Compared with the regularspeed railway,the structure of subway viaduct line has lower stiffness,higher proportion of curve and smaller radius.For the steel spring floating slab track U-beam viaducts line,discrete support of low-stiffness vibration isolators and periodic layouts of low-stiffness U-beams have led to changes of the track stiffness.Since the track dynamic geometric state is controlled by the track static irregularity and the track structure state,when the track structure state is poorly affected by the track stiffness irregularity,the maintenance and management workload of the track static irregularity is large.Whether the existing general-speed railway repair codes are applicable to the vibration-reduction subway viaducts lines needs to be discussed urgently.Based on the vehicle-track-bridge coupling dynamic model and the virtual track inspection method,this paper proposes a method for estimating the static track irregularity management value,which integrates the track dynamic geometric state,vehicle safety index and stability index.The flexible body is generated by dynamic substructure analysis and modal analysis of the rail,floating slab and U-beam finite element models,and then the vehicle-steel spring floating slab track-U-beam viaducts model is established coupled with the multi-rigid body vehicle model.Then,the virtual dynamic irregularity is obtained by frequency-domain integral,filter processing and inversion based on the virtual track inspection method.After comparing and verifying with the actual measurement results of the track inspection vehicle,the influence of the track alignment and superelevation state on the control index of the track static irregularity management value is studied.Finally,the static irregularity management value of the of the straight/curved steel spring floating slab track U-beam viaducts line is calculated respectively,and it is compared with the existing normative control indicators and management values.The main conclusions are as follows:(1)In addition to vertical dynamic irregularities,alignment/horizontal dynamic irregularities also have characteristic wavelengths at 1/n times bridge span.The time-domain peak values were larger than those of the straight viaduct.The overheight of the curve segment has little effect on the track dynamic geometry state,but has significant effect on the safety and stability indexes.(2)The static irregularity management control indexes of straight/curved steel spring floating slab track U beam viaduct line level Ⅰ and Ⅱ are consistent with planned maintenance and temporary repair of general speed railway.The control indexes of grade Ⅲ and Ⅳmanagement,temporary repair and speed limit management of general high-speed railway are distinguished as the track dynamic geometry state.This is because the structural stiffness under the track of vibration absorption type subway overhead line is low,and the track dynamic geometry state has been disqualified when the safety and stability indexes have safety allowance.(3)The management values of straight/curved steel spring floating slab track U beam viaduct line at different stages have a minimum difference of 13%/25% and a maximum difference of 57%/75% compared with general speed railway.Therefore,compared with the static irregularity management standard of common speed railway,it is necessary to include the track dynamic geometric state in the control index of vibration reduction subway viaduct line,and the management standard of common speed railway should not be directly used.(4)The evaluation index of static track irregularity management value is obviously inferior to that of the straight line due to the small radius curved line,with a minimum difference of 14% and a maximum difference of 50%.Therefore,it is necessary to design the static irregularity management standard according to different lines.The research results of this paper put forward suggestions for the scientific management of the static irregularity of the vibration-reduction subway viaduct line.