Experimental study on dynamic response of rock tunnel subjected to train moving load

The tunnels might be suffered from damage and destruction under the dynamic loads generated by trains moving on the upper railways, which can in turn threaten the safety of the railways. Understanding the dynamic response of tunnel under the train moving load is of significance for maintaining the operation safety of both the tunnel and upper railway. However, there is currently a lack of relevant research on this topic, especially regarding model experiments. To address this gap, this paper conducts physical model experiments on the train-rail-bridge-shaking table test system to investigate the dynamic response of tunnels subjected to train moving load. The experiment results revealed that except for the average peak particle velocity (PPA) at tunnel vault, the average PPAs at other locations and the vibration dominant frequency (f0) at all locations increase as the train moving speed (vtr) increases. With the exception of some special cases, the average PPAs on tunnel spandrels are generally less than that on the tunnel vault and greater than that on the tunnel invert. When the vtr exceeds 7.03 m/s, except for the average PPA at tunnel invert, the average PPAs on the tunnel wall are generally larger than those inside the surrounding rock mass. As vtr increases, the average f0 on tunnel wall changes more obviously compared to average f0 inside the surrounding rock mass. When the vtr exceeds 10.54 m/s, the average f0 on tunnel wall are noticeably larger than those inside the surrounding rock mass. The high coefficients of determination obtained from the nonlinear regression analysis indicates a power relationship between the average PPA and vtr, while the average f0 shows an exponential association with vtr. The research findings hold great importance in ensuring the safe operation of tunnels and railways. Physical model experiments were conducted on the train-rail-bridge-shaking table test system, where train moving load was applied through moving of a model train along model tracks. The effects of train moving speed on the particle acceleration and vibration frequency on the tunnel wall and inside the surrounding rock mass were investigated.The relationships between train moving speed and peak particle acceleration, as well as vibration dominant frequency were established using nonlinear regression analysis.