Centrifuge model tests and numerical simulation on ground-borne vibration propagating and vibration reduction scheme for tunnel inner structure

Traffic vibration of roads, trains and metro system is increasingly influencing normal life and facility operation in large cities, as population grows and infrastructures get more congested. Aiming to assess the impact of ground-borne vibrations nearby elevated traffic system on a tunnel housing sensitive scientific in struments, this paper employed centrifugal model tests and numerical simulations to analyze the attenuation trending of vertical vibration propagating from the pile foundation supporting the traffic system and vibratory response of the tunnel model, as well as the passive damping effects of a rubber isolation layer in tunnel structure. Model tests were carried out both in saturated sandy soil layer and dry one, under individual pile vibrations. Results from centrifugal tests indicated that vertical vibration energy decreases with increasing propagation distance, with more rapid attenuation in saturated sands compared to dry sands. Comparison within frequency domain of the vibration shows that high-frequency components attenuated faster than low-frequency ones in the ground, and in the 10–50 Hz range, vibrational energy at the tunnel invert was significantly lower than at the crown, with saturated sands exhibiting lower vibrations than dry sands. However, in the 50–100 Hz range, vibrations at the tunnel invert amplified, with saturated sands exhibiting higher vibrations than dry sands. A 5 mm thick rubber isolation layer was shown to reduce vibrations at the center of the tunnel base between 10–60 Hz in saturated sandy soils. Numerical simulations supported the experimental results and further investigated the impact of soil damping ratio and dynamic shear modulus on vibration propagation. An increased damping ratio significantly reduced high-frequency vibrations and vertical acceleration FRF values. A higher dynamic shear modulus led to decreased soil acceleration response under vibration, though the effect diminished with higher excitation frequencies. This integrated experimental and numerical study provides valuable insights for optimizing vibration reduction strategies in tunnel construction, with potential applications to similar engineering projects.