Abstract: Through the in-situ wave velocity test carried out after the construction of subgrade, the dynamic characteristic parameters of a subgrade-culvert transition zone in high-speed railway were obtained. The longitudinal distributive regularities of dynamic response amplitudes in the subgrade-culvert transition zone were studied by conducting two in-situ tests, respectively during both the comprehensive commissioning test and commercial operation. The comprehensive effects of train speed, running direction and driving load in the adjacent line on the dynamic responses were analyzed. Besides, the distributive regularities of vibration velocity of these two dynamic response tests were compared. Based on these test results, the effective values of vibration velocity and dynamic shear strain were calculated. The results of our study indicate that the train running direction has a significantly effect on the vibration velocity. The increment in the vibration velocity induced by driving load in the adjacent line is not negligible, and the vibration velocity shows positive linear correlation with the train speed. No significant change in vibration velocity between these two tests is found. The dynamic shear strains are less than the one fifth of the average value of the volume shear strain threshold. It can be concluded that the long-term dynamic stability of the subgrade-culvert transition zone can be guaranteed. The analytical approach and related parameters provided in this paper can serve as a valuable reference for railway engineering.

Key words: high-speed railway, subgrade-culvert transition zone, dynamic response, long-term dynamic stability, in-situ test, dynamic shear strain