Research On Mechanical Characteristics Of Stable Work Track Bed Based On Discrete Element

The dynamic stabilization operation can make the loose ballast bed after cleaning and tamping uniformly settle to a stable state,and the overall mechanical properties of the ballast bed are also rapidly improved.In order to perform stable operations with high efficiency and high quality,it is necessary to accurately grasp the dynamic response characteristics of the ballast bed during stable operation and the influence of stable operation parameters on the mechanical properties of the ballast bed.Based on this,the discrete element ballast bed model is established,and the mechanical properties of the static offline test ballast bed,the dynamic response characteristics of the dynamic stable work track bed,and the change law of the mechanical properties of the ballast bed under different stable operating parameters are studied.The main contents are as follows:(1)Establish a real-scale discrete element model based on the real track bed.Through three-dimensional scanning,a ballast model based on the real geometric shape is established,and a discrete element ballast bed model that meets the national standard grading requirements is established through the "particle factory".Finally,the rationality of the discrete element model is verified from multiple angles of the national standard of ballast density reference standard,field static offline test experimental data and stable operation literature calculation results,so that the discrete element model of ballast bed can accurately reflect the mechanical properties of the real ballast bed.(2)Conduct field and offline experimental tests on the track bed before stable operation,and use the discrete element model to study the lateral resistance and vertical stiffness distribution of the track bed.Perform on-site static off-line testing of the ballast bed before stable operation,and perform curve fitting on the collected data.Using the discrete element model,the distribution characteristics of the force bond between the lateral resistance and vertical stiffness of the track bed,the movement characteristics of the ballast under the sleeper,and the sharing characteristics of the lateral resistance of the sleeper are studied.(3)Through the simulation of the dynamic stable operation process,the dynamic response characteristics of the ballast bed in the stable operation process are studied.Starting from the basic theory of ballast bed vibration and the operation principle of dynamic stabilization car,the loading method of excitation load for stable operation and the selection of operation parameters are determined.Under stable operation,the average velocity response of the ballast,the spatial distribution of motion,the vibration displacement response of the sleeper,the change of the average coordination number of the ballast,and the change of contact force,reveal the dynamic response characteristics of the ballast bed in the process of stable operation.(4)Through the adjustment of the excitation value of the dynamic stable operation load,the change law of the mechanical properties of the ballast bed under different stable operation parameters is studied.From the changes of the three stable operating parameters of horizontal vibration frequency,vertical downward pressure and horizontal amplitude force,the change law of ballast bed settlement and ballast bed compactness is studied.And through the establishment of the "particle box" of the ballast under the pillow,the law of the density change of the ballast bed at different depths under the pillow is revealed during dynamic stable operation.Based on the relevant data from the field off-line experiment,a discrete element ballast bed model that meets the initial mechanical performance requirements is established,and the distribution of the lateral resistance and vertical stiffness of the ballast bed under the static offline experiment is studied.Through the simulation of the dynamic stable operation process,the dynamic response characteristics of the ballast bed in the stable operation process are studied.And the change law of the overall mechanical properties of the track bed under different stable operating parameters is studied.The conclusions obtained have reference significance for the response characteristics of the track bed under dynamic stability operation and the selection of dynamic stability operation parameters.