Dynamic characteristics of subgrade-bridge transitions in heavy-haul railways under roller excitation: Fid-Bau Portal

Dynamic characteristics of subgrade-bridge transitions in heavy-haul railways under roller excitation

Li, Shuanglong / Wei, Limin / Chen, Xiaobin / He, Qun / Chen, Aohan

Abstract The dynamic performance of subgrade-bridge transitions containing track components (rails, sleepers, ballast, etc.) in heavy-haul railways has been extensively studied by researchers. However, the influence of subgrade filler distribution on the dynamic performance and stiffness variation has not been characterized due to the laying of track components. This study focuses on the dynamic characteristics of the subgrade-bridge transition before the track components are laid. Field dynamic tests under roller excitation, comprising dynamic stresses, accelerations and displacements, were performed on a subgrade-bridge transition in the Meng-Hua heavy-haul railway, China, and the correlations between the dynamic responses and the filler distribution were analyzed. In addition, a three-dimensional FEM model considering drum-subgrade coupled vibration, which was validated with field measurements, was proposed to investigate the distribution of subgrade vertical equivalent stiffness (VES) and the variation in drum-subgrade contact force. The results show that the dynamic responses, including stresses, accelerations and displacements, are significantly correlated with the filler distribution. The dynamic stress diffusion angle and lateral pressure coefficient in the transition filled with A group filler (well-graded coarse-grained soil with less than 15% fine-grained soil) are different from that in the ordinary subgrade filled with B group filler (coarse-grained soil with 15%~30% fine-grained soil) and C group filler (improved soil contained a local silt clay). Furthermore, the subgrade VES increases approximately linearly from the ordinary subgrade to the transition termination, and the maximum drum-subgrade contact force increases with the increasing stiffness difference between the ordinary subgrade and the transition termination.