Hybrid method combining numerical modelling and experimental measurements for predicting ground-borne vibrations induced by underground trains

Abstract

The environmental vibration problems caused by underground trains have recently received widespread attention. An accurate prediction method is essential for vibration assessment around metro lines and for implementing necessary vibration isolation measures. Previous studies have indicated that a hybrid method that combines numerical modelling and experimental measurements can effectively reduce prediction uncertainty with wide adaptability. However, few studies have reported hybrid methods for predicting environmental vibrations caused by underground trains. However, these methods are limited owing to inconvenient excitation experiments in tunnels. Therefore, this study proposes a convenient hybrid prediction method. Subsequently, an experimental study was performed to validate the applicability of the Betti–Rayleigh dynamic reciprocal theorem to the proposed method. A case study was conducted using numerical simulations to verify the feasibility and accuracy of the proposed hybrid method. Finally, a numerical study was conducted to investigate the influence of adjacent hammer spacing and line-source length on the prediction results. The study results demonstrated that the Betti–Rayleigh dynamic reciprocal theorem is applicable to the proposed hybrid prediction method. Hybrid prediction method has been proven to exhibit high accuracy. The adjacent hammer spacing and line-source length can affect the prediction accuracy. Accordingly, the adjacent hammer spacing should be smaller than 19.2 m, and the line-source length should be larger than 80 m in underground train-induced vibration prediction projects under similar conditions.