Objective Subway shield tunneling operations in hard rock strata are highly prone to inducing vibration in ground surface and adjacent pile foundations. To ensure the safety of surrounding structures, it is essential to analyze the dynamic response patterns of adjacent single piles during shield tunneling in such geological conditions.

Method Methods for onsite vibration monitoring are introduced based on a subway tunneling project underpassing a pedestrian overpass pile foundation. Time-history curves of the monitored ground surface vibration and adjacent pier vibration are analyzed. Based on a coupled DEM (discrete element method) and FDM (finite difference method) calculation approach, a numerical model is established to analyze the dynamic vibration load distribution within the model. Based on this numerical model, the dynamic response characteristics including the pile body horizontal displacement, vibration acceleration time-history curves of the pile body, and the frequency domain of horizontal vibration acceleration at pile top.

Result & Conclusion  Vibration during subway shield tunneling is mainly characterized by low-frequency vibration, with the peak frequency of ground surface vibration concentrated between 3.5 ~ 4.0 Hz. Ground surface vibration in front of the cutterhead is greater than that on the sides, with the weakest vibration occurs behind the cutterhead. When the load amplitude is below 5 mm/s, the horizontal vibration displacement at each monitoring point of the pile body exhibits a linear increase with the increase in load amplitude. Pile foundation vibration induced by low-frequency vibration shows multiple peaks, while under high-frequency vibration, the amplitude of the adjacent pile foundation vibration acceleration is relatively smaller, and the wave peak number is also fewer. The peak frequency of adjacent pile foundation vibration induced by various frequency sources is generally located at half of the load frequency.