| With the increasing vibration and impact on the ballast bed in the way of high-speed and overloading track load,the ballast particles worn and torn,the traction and friction of ballast particles reduced.Under the influence of the repeated and external factors of the track load,the elasticity of ballast bed that tends to stabilize the working state dropped and a large geometrical deformation of ballast bed,these serious consequences made the railway maintenance expense to increase sharply.As a large railway maintenance machinery,the dynamic stabilizing vehicle can effectively improve the repair work of railway,and it can improve the overall stability of the ballast bed and restore the geometry of the ballast bed for the new railway or maintenance line.This paper mainly analyzes the mechanical characteristics of the settlement of ballast bed under the action of track load or stabilizing vehicle,and the interaction mechanism between sleeper and ballast bed.Based on the research of theoretical method,the mechanical properties of ballast bed under different circuit conditions are studied by the discrete element method.Based on the discrete element-finite element coupling method,the paper studies the interaction mechanism between the ballast track structure,tests the compactness of the track bed based on the contact strength method,and maintains the track bed in time to ensure the driving safety.The main research contents and conclusions are as follows:1.The three-dimensional model of sleeper and ballast bed is established through the design and selection of sleeper material,size and ballast bed structure.The discrete element simulation model of sleeper and granular bed is established by the time step of discrete element software EDEM,the contact model is selected and the irregular ballast particle model is simulated.2.Simulation by discrete element,establishing the discrete element simulation model of sleeper and track bed.Based on the discrete element simulation model,analyzing the influence of driving speed and axle weight on the mechanical characteristics of track bed subsidence and the mechanical characteristics of the bed subsidence from the microscopic view.In the certainly cyclic loading times,the results show that,the faster the train speed and the higher the axle weight,the higher the settlement of the track bed.When a certain number of cycles are reached,the ballast particles extrusion of the track bed reaches the stable stage,and the sinking amount of the bed decreases gradually;the relationship between the rotation or movement of the ballast particles and the settlement of the bed is analyzed from the microscopic view without considering the crushing particles.3.Establishing the coupling model of the discrete element-finite element of the sleeper and the granular bed and the coupling simulation analysis,the distribution of the contact force between the sleeper and the ballast particles under different driving speed,the axle weight of different trains,and the geometrical deformation and stress distribution of sleeper under different line conditions were obtained.The results show that the effect of the ballast particles on the sleeper is mainly distributed in the middle and the side of the sleeper.According to the contact strength value between the sleeper and the ballast particles,the relationship between the contact strength value and the track bed subsidence is analyzed,and the results show that the sinking of the bed is increasing with the contact strength.In this paper,based on the theory of discrete element method and particle contact dynamics theory,the contact mechanics behavior of ballast particles is analyzed,and the relationship between the compactness of the bed and the contact strength value is analyzed through the change of contact strength between sleeper bottom and ballast particles.The results show that the greater the contact strength between the sleeper bottom and the ballast particles,the better the contact between the sleeper and ballast particles,and the compactness of the bed is good. |
