| CRTS ? slab track is one of the most ballastless track structures currently used in our country's high-speed railway,and its service performance is good.However,with the increase of operating time,Type ? slab track shows a more significant temperature effect,of which the problem of high temperature arching in summer is more prominent.At present,domestic rectification measures for high-temperature arching of type ? slab tracks include interlayer grouting,rail slab planting,and reflective thermal insulation coating.However,these rectification methods cannot change the longitudinal connection of the track structure,which leads to temperature force accumulation.The fundamental problem.Unlocking the longitudinally connected track structure into a unitary track structure is a new idea to solve the high temperature arching of type ? slab track.However,at present,there are few domestic and foreign systematic studies on the transformation of longitudinally connected systems into unitary systems,and the track structure before and after unlocking is affected.The change of the force system is more complicated.Therefore,the theoretical and technical research on the temperature force release at the plate end of the longitudinally connected track structure system is urgently needed.Aiming at the problem of high-temperature arching of type ? slab track,based on the project of China Railway Corporation(P2018G005),from the perspective of permanently releasing the temperature force between the plates,this paper analyzes the temperature and force release on the front and rear bridges based on the finite element analysis model of type ? slab track temperature and force release The transformation of the stress characteristics of the ballastless track structure.The specific research content and results are as follows:(1)Based on the cohesive force model theory and the concrete damage plastic model theory,the finite element analysis model of the type ? slab track before and after the release of temperature force was established,and the model was verified.Combined with relevant tests and literature,the parameters of cohesion model and concrete damage plasticity were determined.The main structural components of the ballastless track model in this paper are introduced,and the modeling methods of the components and the values of related parameters are introduced.The accuracy of the parameters of the cohesion model and concrete damage plasticity of this paper and the correctness of the finite element model of the long bridge ballastless track seamless line are verified by comparison with field tests and existing literature results.(2)Demonstrate the necessity of temperature force release of type ? slab track.According to the structural characteristics of type ? slab track,a preliminary idea of temperature force release scheme is proposed.In this paper,based on the structural characteristics of type ? slab track,three feasible temperature force release schemes are proposed: the partial longitudinal connection scheme with only the wide and narrow joints removed,the track slab and the mortar layer and the base where the slabs are removed.The full-unit scheme of concrete for slabs and the long-base unit scheme in which two base plates are longitudinally connected on the basis of the full-unit scheme.(3)Based on the established plastic nonlinear finite element analysis model of ballastless track damage,the deformation characteristics of the track after temperature force release are analyzed from the three aspects of temperature load adaptability,lateral stability and longitudinal stability.Some longitudinal connection schemes have strength risks during extreme low temperature loads.A temperature drop above 5°C can cause longitudinal instability of the base plate;anchoring the base plate has little effect on the longitudinal instability of the track structure after limiting the temperature force release.The unlocking scheme that retains the longitudinally connected base plate for unlocking the track plate should be discarded.The temperature force in the track structure of the full-unit scheme is extremely small,but the cost of completely dissipating the temperature force in the track structure is that the track structure generates a certain longitudinal displacement,and the displacement amplitude is within a safe range.The use of base plate planting reinforcement to limit the overall temperature load not only has little effect on reducing the longitudinal displacement of the track structure,so it is more reasonable to not limit the longitudinal displacement of the track structure due to temperature effects.The friction resistance of the "two cloths and one film" sliding layer is not enough to balance the braking force load under extreme braking conditions.To ensure the longitudinal stability of the track structure under extreme conditions,it is recommended to plant more than 8 bars.The temperature deformation of the long base full-unit solution gradually increases from the center of the base plate to the end of the plate,and the peak value of the longitudinal displacement is about 3.27 mm when the overall temperature is raised to 50 °C.Compared with the previous scheme,this scheme saves a lot of construction and is an ideal scheme for temperature force release of the track structure.(4)Designed and checked two limiting methods of anchoring limit in the plate and steel rod implantation in the grouting hole.Combined with the calculation results,it is suggested that if the full-unit solution is used for unlocking,it is advisable to use a grouting hole to implant the steel rod limit.In the field application,rubber materials can be used to wrap the steel rod to reduce stress concentration.If the long base unit is used for unlocking,the position in the base plate should be used to limit the planting bar,and the planting bar should be as close as possible to the center of the unit plate.(5)Based on the finite element analysis model of the CWR on ballastless track of long bridges,the stress deformation characteristics and static characteristics of the CWR and part of the longitudinal connection structure and the whole unit structure are analyzed,and the CWR static The parameters of force characteristics influence the law.In the analysis of expansion and contraction force of CWR,the distribution law of the rail expansion force of the full-unit scheme is similar to that of CRTS III type slab ballastless track and other unit rails.Compared with the type II slab track,the rail expansion force increases sharply,and the peak value of the expansion force increased from 45.3k N to 787.3k N,and the longitudinal force of the abutment caused by the telescopic force increased from 184.48 k N to 892.08 k N.In the analysis of the braking force of the seamless line,the release of temperature force significantly increased the braking force of the rail,and the peak braking force increased from 87.5k N to 249.3k N,an increase of about 185%.The release of temperature force causes the braking force of bridge piers and abutments to increase from 1080.3k N to 2398.6k N under the adverse working conditions of full-bridge braking,an increase of about 122%.The braking force characteristics of seamless lines are greatly affected by the rigidity of the bridge piers and abutments.169 pictures,21 tables,101 references. |
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