| Various sorts of damages appear in the long term service of China high speed railway,such as mortar de-bongding,buckling deformation of slab,broken plate etc.Broken plate is one of the typical damage of ballastless track,which will seriously affect safety and durability of the track structure.Especially in the long-span bridge,due to the complex interaction of beam and track,occurrence of the broken plate may bring more serious derived damages,such as the failure of the support,the instability of the bridge and so on,which may result in the failure of the whole track bridge system.Therefore,it is of great significance to research the influence of broken plate and evaluate the reliability of the ballastless track-foundation system.In this paper,CRTSⅡ slab ballastless track on long-span bridge under the conditions of broken slab is taken as the research object.Through the establishment of finite element model,impacts of broken plate on force characteristics of slab track-bridge system are analyzed.And a method is proposed to evaluate reliability of ballastless track-bridge system in damage condition based on the theory of structural reliability,which will guide the track maintenance.The main work and conclusions of this paper are as follows:(1)Based on the finite element method,two nonlinear space coupling finite element models of CRTSⅡ slab track on long-span bridge are established.In these models,rail and bridge are simulated by Euler beam element,while track plate and base plate are simulated by 3D solid element.Multi-scale simulation of large scale bridge and small scale damage are completed.And coupling of the long bridge beam unit and the base plate space solid element are achieved.(2)For the damgage of track plate cracking of CRTSⅡ slab ballastless track on long-span bridge,influence of different temperature,different fracture position and different depth of fracture on force and deformation of ballastless track is analyzed.The results indicate:temperature drop range and fracture depth have great infulcence on the components of track structure.When the overall temperature decline is higher than 30℃,and the fracture depth is more than 180mm,additional longitudinal force of the base plate about 30m near the broken seam exceeds the ultimate tension value,and the base plate has risk of cracking.When temperature drop range exceeds 15℃,and the fracture depth is more than 20mm,longitudinal resistance of fasteners about 50m near the fracture exceeds limit value,and the rail will creep.CA mortar layer will cause shear failure.The most unfavorable fracture position of the track plate is at the sliding support on the right side of the continuous beam.(3)For the damgage of base plate cracking of CRTSⅡ slab ballastless track on long-span bridge,influence of different temperature,different fracture position and different depth of fracture on force and deformation of ballastless track is analyzed.The results indicate:temperature drop range and fracture depth have great infulcence on the components of track structure.When the overall temperature decline is higher than 30℃,and the fracture depth is more than 180mm,additional longitudinal force of the track plate about 20m near the broken seam exceeds the ultimate tension value,and the track plate has risk of cracking.When temperature drop range exceeds 5℃,and the fracture depth is more than 20mm,CA mortar layer will cause shear failure.The most unfavorable fracture position of the base plate is at the sliding support on the right side of the continuous beam.(4)Based on the Monte Carlo sampling method,combining MATLAB and ABAQUS software,a method to analyze the reliability of ballastless track under disease condition is proposed.Taking the CRTSⅡ slab track on long-span bridge with base plate fracture as an example,track reliabilities are analyzed from the components and overall perspective.The results of calculation and analysis show that the failure probability of the track slab is maximum,it’s up to 28.3%. |
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