Research And Optimization Analysis On Lateral Resistance Of Composite Sleeper

Composite sleeper have the advantages of renewable,wide application range,convenient installation and maintenance,good durability,low life cycle cost and various types.However,due to the low density and smooth surface of composite sleeper,the lateral resistance is lower than that of concrete sleepers,which limits its wide application to a certain extent.At present,the domestic and foreign related research on the lateral resistance of composite sleeper is relatively limited.In view of this,in order to solve the problem of insufficient lateral resistance of composite sleeper,this paper puts forward several optimization schemes for FFU sleeper.Based on the ballast bed test platform,a series of tests on lateral resistance of concrete sleeper,strip composite sleeper and optimized composite sleepers are carried out,and the lateral resistance of various types of sleeper is quantitatively analyzed.On this basis,this paper establishes a three-dimensional DEM numerical model of sleeper-ballast bed,compares the difference of the effect of different optimization schemes on the lateral resistance of composite sleepers,studies the regulation of the lateral resistance sharing,further analyses the contact characteristics between sleepers and ballasts from the mesoscopic level,and clarifies the interaction mechanism between sleeper and ballast.The main work and achievements of this paper are as follows:1.Through ballast bed test platform,a series of lateral resistance tests are carried out.Aiming at FFU sleepers,this paper puts forward various optimization schemes.Based on ballast bed test platform,a series of tests on lateral resistance of concrete sleepers and strip,textured and structure-optimized composite sleeper are carried out.The difference of lateral resistance between strip composite sleeper and concrete sleeper under the same ballast bed geometric section is compared,and the influence of ballast bed shoulder size on the lateral resistance is revealed.The effect of textured and structure-optimized composite sleepers on the lateral resistance is clarified,which enriches the study of mechanical properties of composite sleeper and ballast bed,and provides experimental data support for numerical simulation.2.Establish the sleeper-ballast bed DEM model and carry out meso-numerical analysis of lateral resistance.In this paper,3D scanning technology is used to extract the geometric shape of ballast particles and establish the ballast particle template library.A three-dimensional DEM model of full-scale sleeper and ballast bed is established based on the relevant experimental parameters,and the reliability of the numerical results is verified.The lateral resistance numerical results of concrete sleepers,strip composite sleeper and various optimized composite sleepers are compared and analyzed and the difference of improvement of each optimization scheme is analyzed.The sensitivity analysis of relevant influencing parameters,including ballast shoulder and ballast bed density,is carried out.3.Based on the DEM model,the regulation of lateral resistance sharing is clarified,and the law of lateral resistance evolution of ballast bed is deeply understood.In this paper,the resistance development process of the bottom,side and end of the sleeper during the lateral displacement is recorded while the DEM is used to simulate the lateral resistance.The regulation of lateral resistance sharing of composite sleeper is clarified,and the different effects of various types of optimized composite sleepers on the resistance of each part are analyzed,which verifies the correctness of the optimization idea of composite sleepers proposed in this paper.4.Based on the DEM model,the interaction mechanism between sleeper and ballast particles is analyzed from the meso-level.Based on the numerical calculation of discrete element method,this paper studies the distribution of contact force bound in the ballast bed and the contact between sleeper and ballast particles,reveals the meso-distribution of contact force in the ballast bed,clarifies the force situation of sleeper and ballast particles,summarizes the influence of various optimization schemes on the micro-contact characteristics,and lays a foundation for the structural innovation of sleeper.