Real-time evaluation of mechanical qualities of ballast bed in railway tamping maintenance

•A novel test device assessing the impact force on tamper was proposed.•Macro-mechanical properties of ballast bed and tamper were studied experimentally.•Micro-mechanical properties of ballast and tamper were analyzed numerically.•Real-time evaluation of ballast bed was innovatively achieved. Real-time evaluation of the mechanical qualities of ballast beds is essential for improving tamping effort in railway maintenance. This study aims at evaluating the mechanical qualities of ballast beds based on the impact force on tamper. A novel test device was newly developed to assess the impact force on tamper. This device has high accuracy and long service life. The mechanical qualities of ballast bed and the impact force on tamper were studied experimentally. Results indicated that tamping decreased the lateral resistance and support stiffness of ballast bed by 38.57%–54.08% and 46.92%–62.42%, respectively. Furthermore, a tamping-ballasted track coupling model was constructed and validated by comparing the mechanical qualities of ballast bed between the test and simulation. The dynamic characteristics of ballast and tamper were analyzed numerically. A mathematical expression was developed to invert the mechanical qualities of ballast bed based on the impact force on tamper according to the numerical results. Thus, an innovative real-time evaluation of the ballast bed was achieved by combining the proposed test method and mathematical expression. This study helps to conveniently collect health information of ballasted track at a low cost. [Display omitted]