Experiment And Simulation Analysis Of Ballast Breakage And Its Effects On Railway Gravel Bed

Ballast track structure due to low construction cost,short period,maintenance is convenient and fast,vibration reduction and drainage performance is strong and other advantages are widely used in China’s ordinary passenger and freight lines,heavy-haul railways and some high-speed railways.But one of the most common problems in the ballast track structure is that the line traffic(load cycle number)continues to increase,ballast gradually deteriorated phenomenon.Due to the ballast corner crushing,pulverization crushing,overall splitting,the dynamic load between the wheels and the railway tracks increased significantly,eventually resulting in the differential settlement of the track structure and track irregularity,seriously affecting the safety and comfort of the train operation.Based on the above existing problems,this paper adopts the method of combining Laboratory test and simulation to carry out research on the breaking law of railway gravel ballast particles.The specific research contents and results are as follows:(1)Based on the independent design of a single ballast compression and shear integration device,the single static compression test and shear test of railway gravel ballast,analysis of the broken form of ballast particles,and statistics of square,conventional,needle,flake ballast particles in different particle size grading under the change of breaking strength,The normal distribution model and Weibull distribution model are used to characterize the distribution law of particle breaking strength,and provide experimental reference for the calibration of particle breaking parameters of ballast.(2)Based on the principle of the discrete element method and can be broken ballast grain refinement of modeling were discussed,set up single ballast static compression and shear broken numerical simulation,through compared with the indoor experiment,research based on grid partitioning can be broken ballast particles under the rationality of the modeling method for ballast provide fine particle breaking parameter calibration modeling basis.(3)Using Box-Behnken test design method,combined with conventional ballast,needle ballast,flake ballast three different forms,the critical compression crushing strength,critical shear crushing strength,normal stiffness and tangent stiffness under the influence of single ballast crushing simulation design,and the simulation test results for regression analysis,Obtain the response surface of discrete element ballast crushing parameters;The target test results of compression crushing strength and shear crushing strength were taken as the target parameter optimization.Finally,the correctness of the optimized parameters was verified by direct shear test.(4)Modeling way based on single grain refinement and fracture parameters,establish railway gravel sheets pillow simulation model,to study the change characteristics of ballast bed under the train load state,and explore the train loads to the ballast bed particle degradation influence,for the high-speed rail frantic jumble orbit design,construction and operational condition assessment and provide a scientific basis for maintenance and repair.