Discrete Element Analysis on Mechanical Properties of Ballast Bed by Tamping in Railway Turnout Areas

Turnout is the key component of the railway tracks for trains to change direction, which is vital to operational safety and passenger comfort. Therefore, it is of great importance to perform a scientific and reasonable tamping operation for turnout areas. In this paper, based on the commercial software edem and recurdyn, a coupled simulation model of the large machine tamping device-rail-sleeper-ballast bed in the turnout area is jointly established, and the correctness of the model is verified by the test results of the lateral resistance of the ballast bed. The influence of tamping operation on the macro-and micromechanical properties of ballast bed at the switching part of railway turnout areas is studied and recommendations for the optimization of tamping operation are proposed. The results show that in the squeezing stage, strong force chains are distributed concentrately under sleepers, where the distribution range is approximately elliptical with a depth of 150 mm. After tamping, only the 200-mm ballast under the sleepers is compacted, where the compactness is increased by 5.9%. On the contrary, the compactness of the ballast in the sleeper crib is reduced by 27.4%, which is the weakest part. To ensure favorable tamping quality, the tamping sequence at the switching part of railway turnout areas is suggested to be conducted in order of first through track and then diverging track.