Abstract: To solve the problem of mechanical response behavior of track and subgrade, and the structure design of subgrade bed under overweight goods, an integrated model of track and subgrade was established. Based on soil elastic-plastic theory, the response laws of the track and subgrade under overweight good were analyzed. The mechanism of the spatio-temporal evolution of the mechanical properties were revealed, and the overall thickness of the track and subgrade was recommended under overweight goods. Results show that, the dynamic bending stress value imposed on the rail does not exceed the allowable value. The maximum pressure of the sleeper is 222.2 kN, which is close to the designed bearing capacity, 230 kN, of the cross-section of type Ⅲ sleeper. The bearing capacity of the ballast track structure does not satisfy the transportation requirement of overweight goods. Therefore, the subgrade bed must be adequately tamped and compacted before and after the trains pass the railway. The maximum dynamic stress at the top of the subgrage bed is 197.37 kPa, which is more than the critical dynamic stress, 169 kPa, of group A filler. The overall thickness of the track and subgrade should be 4.3 for overweight goods. The results of this work can provide theoretical basis and technical reference for the safe transportation of overweight goods and the maintenance of the track and subgrade.

Key words: railway transportation, overweight goods, integration model, stress distribution, subgrade bed design