Vibration emission from railway lines in tunnel - characterization and prediction

A method for characterizing and predicting vibration emission from railway lines in tunnels is presented. The characterization method consists in measuring both the tunnel vibration response during train pass-by events and the tunnel effective mobility (mobility combining point and transfer mobilities), from which the line of uncorrelated forces characterizing the source can be calculated. The results from field measurements of commuter train operations are presented and improved using a numerical tunnel/groundmodel. The transfer of an existing situation to a new one is performed using two different train/track/tunnel models. The situation change is expressed in terms of difference in the force density applied to the tunnel invert between the original and the new situation. The track models are first calibrated from the characterization field measurements and then used to estimate a given situation change. The results of the two models/procedures compare rather well, thus cross-validating the approaches.