Refined Modeling And Discrete Element Analysis Of Particle Crushing Of Railway Track Bed

Railway transportation is not only a necessary travel mode in people’s daily life,but also the main artery of national economic development.With its own economy and applicability,ballasted tracks are widely used in passenger and freight transportation.The ballast bed is a granular system composed of a large number of ballast particles.The crushing of the ballast particles under the action of the train load is an important reason for the decrease of the overall mechanical properties of the ballast bed.Therefore,research on the crushing process of railway ballast particles has great theoretical significance and practical engineering application value.Based on the real shape of the ballast particles,this paper realizes the fine modeling of the particle crushable model.Using numerical experiments as the research method,from the perspective of single particle and particle system,the process of ballast particle crushing in railway ballast bed is studied.The specific work content is as follows:(1)Using a three-dimensional laser scanner to collect ballast particle information,based on the dense point cloud on the surface of the particle,reconstruct the refined model of the ballast particle,and establish a three-dimensional model library of the ballast particle.And with the characteristic length of particles as the core parameter,a three-dimensional evaluation index for particle shape analysis is established.(2)The dynamic filling method is proposed,based on the real shape of the ballast particles,the granular crushable model is refined,and the single-particle unconfined uniaxial compression numerical test scheme is used to analyze the single-particle crushing process by using the general method of particle crushing analysis..The results show that there are obvious phase changes in the single particle crushing process,which can be divided into the following four stages: particle rotation,contact stability,partial crushing and complete crushing.(3)Starting from the external and internal influencing factors of the numerical experiment,the controlled variable method is adopted to study the influence of loading speed and particle shape on single particle crushing.The results show that the loading speed and particle shape have a significant effect on the crushing process of single particles.The former is reflected in the fact that the local fragmentation of the direct contact area between the particles and the loading plate will increase with the increase of the loading speed.The latter is affected by the irregular appearance of the ballast particles,resulting in the flatness of the particle surface affecting it and the loading.The contact area of the board surface.The more flat the particle shape is,the more obvious the brittleness of the particle is broken.(4)Using the method of irregular particle spatial distribution,based on the box-type numerical test scheme,a simplified model of the ballast particle system is established,and the crushing process of the ballast particle system is analyzed from the macro and meso perspectives.The results show that: from a macro perspective,the crushing of the ballast bed particle system presents a staged change,which can be divided into four stages: particle compaction,crushing initiation,crushing accretion,and late crushing.From a meso-level perspective,there are three major characteristics of ballast particles being broken by the interaction between the particles: corner breakage,crushing crushing,and multi-point contact.