Influencing Factors of Dynamic Performance of Jointless Turnout on Bridge in High-Speed Railway

Taking the case of 18# turnout (350km/h) laid on 6×32m continuous girder, a dynamic model for coupling system of vehicle and jointless turnout on bridge was established to analyze the factors that affected dynamic performance of jointless turnout on bridge, and several aspects were taken into consideration, i.e. train’s running quality, rail stress of turnout, vibration of turnout and bridge, and deformation, etc. It is shown that influenced by vibration and deformation of bridge, the train, turnout and bridge form a coupling vibration system, whose dynamic responses are stronger than those caused by train/turnout interaction on subgrade. Wheel/rail contact of turnout zone (especially the frog) has great effect on dynamic responses of jointless turnout on bridge, thus the nose rail height of frog should be optimized to mitigate the wheel load transition and its longitudinal gradient. When a train is passing a jointless turnout on bridge, a reasonable vertical stiffness for bridge is the key to keep its safety and comfort; as for the 32m continuous girder, the ratio of deflection to span should be ≤1/9000 under the ZK load (Chinese standard).