Study On Acceleration Threshold For Train Control In Earthquake Early Warning System For High-speed Railways

Earthquake may ruin lines, bridges, and tunnels of railway, and cause high-speed trains to derail from the track and casualties. Except for enhancing capacities of railway structures, it is necessary to establish earthquake early warning system for mitigating the effects of earthquake. Development of earthquake early warning system can guard the safety and stability of high-speed trains more effectively. Whether earthquake alarm threshold of earthquake early warning system are determined reasonably be closely related to the effectiveness of the system. So, as to the problem of earthquake alarm threshold in earthquake early warning system, this paper launches the following researches:(1) Basic principals of earthquake early warning and its application to railways are presented. The state-of-the-art of earthquake early warning systems for high-speed railways around the world is introduced. Main points in development of earthquake early warning system for high speed railways are discussed, including threshold for early warning, layout of monitoring stations, train operation and structure of the early warning system.(2) In order to research the stability of trains moving over bridges shaken by earthquakes, this paper establishes vehicle-bridge interaction analysis model. The idealized model for each 4-axle 2-bogie vehicle in a train can be modeled by a 27-DOFs dynamic system and Bridge model uses modal synthesis analysis (the superposition method of mode of vibration). Assuming there is not relative displacement between wheels of trains and bridge, vehicle model and bridge model can be coupled together.(3) Using SI index, running safety assessment of trains moving over bridges subjecting four earthquake waves (PGA:100 gal) is implimentded. When subjecting to El Centro and Northridge earthquake waves, trains can run safely. However, trains may derail when subjecting to TAP003 and TCU068 earthquake waves.(3) Earthquake alarm thresholds of the four typical waves are obtained utilizing this methodology. When trains moving over bridges at the speed of 350 km/h subject to El Centro, Northridge, TAP003 and TCU068 earthquake waves, earthquake alarm thresholds are 219.71 gal,146.46 gal,46.47 gal,77.20 gal respectively.