Numerical validation of a simplified source-receiver mobility approach for estimating building floor velocity responses to railway vibration

Prediction methods are required for designing buildings to protect inhabitants against ground-borne (structure-borne) sound from railway lines or other outdoor ground vibration sources. There is no European standard for such predictions yet, but a European task group (CEN/TC126/WG2/TG1) is now doing preliminary work on this subject. A promising approach, based on the source-receiver vibration system methodology (the building foundations being the source and the building upper-structure the receiver) and using a mobility approach, has been identified and presented at Forum Acusticum in 2023. In the present paper, the approach is numerically validated in a simple 2.5 D configuration (3D but infinite in one direction) of a building along a railway line. The floor velocity responses are estimated first using a numerical BEM model taken as reference model and then using a simplified mobility approach, where railway excitation is expressed as a line of uncorrelated forces applied to ground and the source-receiver mobility system expressed using effective mobilities (velocity response to a line of uncorrelated forces). The two floor velocity responses obtained are compared and the assumptions required for easily solving the systems discussed.