Dynamic Behavior of the Tunnel Ground Assembly Under Harmonic Excitation: Experimental and Numerical Studies
摘要
In real-world subway transportation, the tunnel-ground system is usually subjected to complex multi-frequency excitation, which can be considered as a superposition of numerous harmonic loads. This paper investigates the dynamic response of a tunnel-ground system due to stationary harmonic loads applied on the tunnel invert.
MethodsModel test and numerical modelling results are used for the investigation. In the model test, the transfer ratios between acceleration responses of the target points and path points in the frequency domain of 31.5–200 Hz are calculated to analyze vibratory propagation characteristics in the tunnel and surrounding soil along various directions. Internal forces of the tunnel lining are computed based on the measured strains and material parameters at testing locations.
ResultsThe loading frequency is taken into account in both analyses related to the acceleration and internal force responses. Moreover, results obtained from the 3-dimensional numerical model are compared with the experimental ones. It is shown that the numerical model with transversely isotropic soil shows a good match with the experiment in the presented examples. Eventually, through the validated numerical model, the complete circumferential distributions of internal forces regarding the lining sections of interest are calculated and discussed.
ConclusionAs the study is carried out concerning a specific site along the metro line, the dynamic behavior found in this work has the potential to provide vital information for vibration mitigation measures given similar geological conditions.