Resilient modulus of fine-grained subgrade soil considering load interval: An experimental study

On automatic block lines, there is a time interval between two trains traveling on a track in the same direction. Therefore, the dynamic load on the railway subgrade is composed of the periodic vibrations generated when the train passes, and the intermittent period when there is no train passing. To study the influence of the train interval time on the dynamic behavior of a railway subgrade, a series of dynamic triaxial tests of heavy-haul railway subgrade soil were conducted under consecutive cyclic loading and intermittent cyclic loading, while considering the interval time. The variation laws of the resilient moduli of specimens with different moisture contents and stress states with loading cycles under the two loading modes were compared and analyzed, and the influence of the load interval on the resilient modulus was discussed. The results showed that the load interval improved the resilient modulus of a specimen and its ability to resist failure. When the specimen was in a saturated state, its resilient modulus tended to increase with an increase in the intermittency period. A prediction model considering the soil stress state and load interval was proposed, based on introducing a factor k(4) to quantify the effect of the load interval on the resilient modulus.