Effect of Squeezing Force of Tamping Picks on Ballast Bed during Three-sleeper Tamping Operation
To study the relationship between the squeezing force of the tamping picks and the state of the ballast bed in the three-sleeper tamping operation,simulated polyhedral ballast particles were generated based on computer imaging technology.Considering the complex force transmission process between the tamping picks and the ballast,the virtual el-ement was proposed to simulate the action of the squeezing cylinder.The DEM-MBD coupling algorithm and the Hertz-Mindlin Nassauer Kuna constitutive relation were utilized to establish the three-sleeper asynchronous tamping machine-track panel-ballast bed coupling analysis model.The correctness of the simulation model was verified by the field meas-ured data of the self-developed three-direction vibration sensor(TAB).On this basis,with the revealing of the evolution process of contact force fabric of ballast particles in ballast bed during squeezing stage,the influence of squeezing force on local compactness of ballast bed,motion characteristics of ballast particles,contact state of sleeper and ballast bed stiffness was analyzed from macro-meso perspectives using mathematical statistics principle.The results show significant anisotropy in the distribution of normal and tangential contact forces of ballast particles in the ballast bed during the squeezing stage.The sleeper bottom is more sensitive to the squeezing force.Both the smaller and larger squeezing forces can lead to larger mathematical expectation and variance of ballast particle velocity distribution in the upper part of the sleeper bottom,which is not conducive to the compaction stability of ballast particles.At the squeezing force of 7.8 kN,the ballast bed stiffness can reach the maximum value of 41.43 kN/mm,with optimal sleeper contact state.Therefore,it is suggested that at the track lifting amount of 30 mm,the squeezing force of a pair of tamping picks should be 7.8 kN.The squeezing force of tamping picks should be customized according to the track lifting amount in the maintenance,so as to ensure the quality of the three-sleeper tamping operation.
ballast bedpolyhedral ballast particlesthree-sleeper asynchronous tampingdiscrete element methodcontact fabric
万方数据
维普
