Study On Longitudinal Force Of CRTS? Slab Track CWR On Bridge

With the sustainable development of China high-speed railway and implementation of the "going out" strategy.CRTS III slab track,as a new type of track structure independently developed in China,is widely used in CWR on bridge,which can meet the strict requirements of high-speed railway for operational safety and train running stability.The mechanism of beam-slab-rail interaction is relatively complicated and was made less relevant research.The excessive interlayer interaction force will lead to rail broken,cracking of interlayer contact,structural damage of internal convex block,elastic layer and isolation layer,which will affect the safe service of CRTS III slab track CWR on bridge,and even endanger the safety of train running on bridge.Based on comprehensive analysis of the research status of longitudinal force of CWR on bridges at home and abroad,the longitudinal force of CRTS? slab track CWR on bridge with multi-span simply supported beam bridge and long-span continuous beam bridge were investigated comprehensively in this article,which from the static and dynamic perspectives respectively.The main research works include as follows:1.Spatial coupling model for CRTS? slab track CWR on bridge.According to the structural composition and features of CRTS? slab track,multi-span simply supported beam bridge and long-span continuous beam bridge,which were widely used in China high-speed railway.Based on mechanism of beam-slab-rail interaction and finite element method,spatial coupling model of CRTS? slab track CWR on bridges were established respectively by ANSYS,in which spatial geometry and mechanical property of the rail,fastener,track slab,self-compacting concrete layer,convex block,elastic cushion,isolation layer of geotextiles,bed plate,bridge beam,support on pier and abutment top were considered in details.2.The calculation program for longitudinal force of CRTS? slab track CWR on bridge.Based on C# advanced programming technology and parameterized language APDL,the secondary development of ANSYS was realized,calculation program of CRTS? slab track CWR on bridge was accomplished.Such program can realize parameter setting,model establishing,calculation loading,calculated data post-processing,among them,structural parameters includes spatial geometry and mechanical parameters of track and bridge structure,as well as load parameters such as complex temperature load,train load and braking load.Comparison with the existing research results verifies the accuracy of static and dynamic analysis using the model created in this article,and the universality and reliability of the calculation program.3.Study on static characteristics for longitudinal force of CRTS? slab track CWR on bridge.On the basis of the calculation program and from the static force,the characteristics of expansion-contraction force,deflection force,braking force and rail breaking force of CRTS? slab track CWR on bridge were studied,and the most disadvantageous conditions were summarized.Among them,various complex temperature loads including bidirectional non-linear temperature gradient of bridge beam and vertical temperature gradient of track slab were considered,various loading modes were considered for train load and train braking load,the influence of different broken locations temperature loads of rail were considered in the calculation of rail broken value.It was suggested that the overall temperature load,train load and braking load of full bridge,and the location of maximum expansion-contraction force should be selected as the rail broken position to design checking of CWR on bridge.On this basis,safety checks for rail strength,rail broken value,elastic cushion deformation and relative displacement between adjacent layers were carried out respectively.It was suggested that the spacial coupling finite element model based on beam-slab-rail interaction method should be adopted in the calculation of rail broken value and rail breaking force.The study provides a theoretical basis for the design checking method and reasonable checking load of CRTS? slab track CWR on bridge.4.The influence factors analysis on longitudinal static force of CRTS? slab track CWR on bridge.On the basis of the calculation program and from the static force,the rules of how related parameters,such as longitudinal stiffness of fasteners,laying scheme of small resistance fastener,bearing arrangement,longitudinal stiffness abutment and pier top,were investigated.From the point of view of reducing the static longitudinal force of structures,reasonable suggestions were put forward for the choice of fasteners and laying scheme in the design process,the reasonable value range of structural parameters of track and bridge was given,as well as the simplified method of bridge span and beam section in the process of structural checking calculation.The results show that the bridge with smaller temperature span is more advantageous to the longitudinal force of track and bridge structures,and the bearing arrangement should follow this principle.The model of continuous beam bridge with constant section is not suitable for the calculation of deflection force.The study provides references for structural design improvement and laying method of CRTS? slab track CWR on bridge.5.Study on dynamic characteristics for CRTS? slab track CWR on bridge.Taking the middle span of double-track long bridge in this paper as the research object,on the basis of the CRH2 high-speed EMU with 8 sections and from dynamic force,the longitudinal wheel-rail force during uniform running and rapid braking of the train was obtained by calculation formulas.The longitudinal and vertical dynamic characteristics of ballastless track and bridge structures under the conditions of uniform running and rapid braking of the train were analyzed.It was suggested that the selection of static and dynamic loads in the calculation of CRTS III slab track CWR on bridge by comparing with the results of static calculation.The results show that the longitudinal displacement and acceleration of ballastless track and bridge structures have reversed abrupt changes in varying degrees at the moment of train start braking and stopping,the relative displacement between rail and track slab,and longitudinal force of pier top are disadvantageous when the train braking in the direction of fixed support.It was suggested that the deflection force and braking force of CRTS III slab track CWR on bridge should be calculated according to the static load in the code.The study provides a theoretical basis for the structural stability of CRTS III slab track CWR on bridge during operation.