AbstractsTransportation

With the rapid economic and urban development, the high-speed railway system connecting major cities serves as a vital role in the national transportation network. Due to its high speed, punctuality, safety, comfort, high transportation capacity and less land use, it has become a new trend of railway development in the world especially in Asian and European countries. We have derived the benefits of high-speed railways since Tokaido Shinkansen as first high-speed railway was began operations in Japan in 1964. The main railway lines usually pass directly over densely populated urban areas or high-tech industrial areas, where the railway structure mainly comprises elevated bridges. Considering the extremely high speed, the bridge vibration caused by running high-speed train (HST) is concerned. This long-term vibration may cause deterioration of the bridge structures, such as the cracking or exfoliation of concrete. On the other hand, the bridge vibration propagates to the ambient ground via footing and pile structures, thereby causing long-term environmental problems. Those vibrations often bring annoyances to the residents alongside railway lines and malfunction to the vibration-sensitive equipment housed in the nearby buildings. Furthermore, they can induce the secondary vibration of the buildings, which seriously affect the structural safety of ancient buildings near the railway lines. Along with further urbanization and more rapid transport facilities, there is rising public concern about the environmental problems in modern Japan. Therefore, it is quite necessary to clarify the development and propagation mechanism of ground vibration caused by running HSTs on the rigid-frame viaducts (RFVs) to find out more effective countermeasures against the HST-induced vibration problems. In this study, the vibration issues related to the train-bridge-ground interaction system: the HSTinduced bridge vibration problem, the environmental vibration problem caused by running HSTs and the vibration reduction method, have been investigated by the 3D numerical analysis approach. For the HST-induced bridge vibration problem, it is very important to perform effective prediction and diagnosis on the HST-induced vibration of either existing bridges or those in the planning stage and obtain some instructive information for the ground vibration analysis as well as the vibration mitigation analysis. An analytical procedure to simulate the train-bridge coupled vibration problem with considering the train-bridge interaction (TBI) as well as the effect of ground properties is established. The vibration responses of RFVs caused by running HSTs are analyzed in consideration of the wheel-track interaction including the rail surface roughness. The RFVs including the track structure are modeled as the 3D beam elements and simultaneous vibration differential equations of the bridge are derived by using modal analysis. The elastic effect of ground springs at the pier bottoms and the connection effect of the sleepers and ballast between the track and…