Research On Mechanical Characteristics Of Assembled Vibration Reduction Track In Urban Rail Transit

In recent years,China’s rail transit has developed rapidly.Track structure,as a system to bear train load and guide the train to run safely and comfortably,is the key to affect the development of rail transit.The traditional track structure of urban rail transit has many problems,such as complicated construction procedure,low efficiency in construction,poor smoothness of the line,serious vibration and noise,frequent disease,difficult maintenance and so on.These problems will restrict the development of urban rail transit.The assembled vibration reduction track structure adopts composite structure of slab and pad,which is prefabricated in the factory and assembled on site.The construction is rapid.The flexible isolation structure of rubber damping pad is adopted,which can effectively reduce the vibration and noise,and it is convenient for maintenance.The assembled vibration reduction track has a broad development prospect.However,most of its research are focused on construction,and its mechanical characteristics are still lacking.Therefore,it is urgent to study the static and dynamic characteristics of assembled vibration reduction track,so as to provide theoretical guidance for its engineering optimization design and popularization.Aiming at the mechanical characteristics of assembled vibration reduction track structure,the static analysis model of assembled vibration reduction track structure was established based on finite element theory,and based on the finite element and multi-body dynamics theory,the rigid-flexible coupling dynamic analysis model of six marshalling metro trainassembled vibration reduction track-foundation was established.The static and dynamic responses of assembled vibration reduction track structure were calculated and analyzed,and its mechanical characteristics were studied.The system tests of assembled vibration reduction track structure were carried out,and the performance of assembled vibration reduction track structure,such as vibration reduction,limit,anti-floating and replaceable performance,were analyzed and studied.The main research contents and conclusions are as follows:(1)The static analysis model of assembled vibration reduction track and the rigidflexible coupling dynamic analysis model of train-assembled vibration reduction track-foundation were established.Based on the finite element theory and according to the design parameters,a fine finite element model for static analysis of assembled vibration reduction track was established considering the geometric nonlinear characteristics of rubber damping pad conical truncated top.Based on the finite element and multi-body dynamics theory and according to the measured load-displacement data,the rigid-flexible coupling dynamic analysis model of six marshalling metro train-assembled vibration reduction track-foundation was established,and the nonlinear characteristics of rubber damping pad stiffness was taken into consideration in the model.And the correctness of dynamic model was verified.(2)The static characteristics of assembled vibration reduction track under train load,temperature load and their combined action were studied.Based on static analysis model of assembled vibration reduction track,the static characteristics of assembled vibration reduction track structure under train load,temperature load and their combined action were studied,and the most unfavorable position and the critical load position of assembled vibration reduction track structure were explored,from the aspects of structural deformation,stress distribution and bending moment distribution.(3)The dynamic characteristics of assembled vibration reduction track on different foundations were studied,and the influence of train and track structure key parameters were analyzed.Based on the rigid-flexible coupling dynamic analysis model of train-assembled vibration reduction track-foundation,the dynamic characteristics and the vibration distribution characteristics of assembled vibration reduction track under train load were studied from the aspects of wheel-rail interaction,train operation safety and comfort,track and foundation dynamic response,etc.And the vibration reduction effect of assembled vibration reduction track on different foundations were evaluated.The results show that the insertion loss of assembled vibration reduction track on different foundations is greater than 10 d B,the vibration reduction effect is significant.Based on the rigid-flexible coupling dynamic analysis model of train-assembled vibration reduction track-foundation,the influence of train and track structure key parameters were analyzed from the aspects of train and track dynamic responses and vibration reduction effect of track.It was found that the dynamic responses of train and track increase with the increase of train speed,but the influence of train speed on vibration reduction effect is not obvious.With the increase of rubber damping pad stiffness,the dynamic response of train changes little,the displacement of structure above rubber damping pad decreases gradually,and the vibration of base slab increases gradually,the vibration reduction effect becomes worse.Considering the nonlinear characteristics of rubber damping pad stiffness,the insertion loss of the base slab increases by 3.36 d B,and the vibration reduction effect is more significant.(4)The mechanical performance system tests of assembled vibration reduction track structure were carried out,and its vibration reduction,limit,anti-floating and replaceable performance were studied and analyzed.The wheelset drop test,slab pushing test,concrete pouring test and slab uncovering test of assembled vibration reduction track were carried out,and its vibration reduction,limit,anti-floating and replaceable performance were studied.The results show that the foundation insertion loss measured by wheelset drop test is 7.7-9.2d B,the vibration reduction effect is significant.And the vibration reduction performance,limit performance,anti-floating performance and replaceable performance of assembled vibration reduction track is excellent.Based on the simulation calculation and test method,the static and dynamic characteristics of assembled vibration reduction track structure were systematically studied in this paper,and the structural performance of assembled vibration reduction track structure were evaluated,such as vibration reduction,limit,anti-floating and replaceable performance,so as to provide theoretical guidance for the theoretical checking,design optimization,engineering application,operation and maintenance of assembled vibration reduction track structure.