Abstract: The authors investigate the dynamic response patterns of single piles at varying pile-to-tunnel distances induced by shield tunneling. The discrete element method-finite difference method (DEM-FDM) is employed to develop a two-dimensional dynamic coupling model of the tunnel structure, soil, and pile, based on field measurement data. A case study is conducted on a section of Jinan metro line 4 in China. DEM is used to simulate the properties of soil materials, while FDM enables efficient dynamic calculations of concrete structures, simulating the dynamic responses of single piles within an 18 m radius of the tunnel under different pile-to-tunnel distances. Shield tunneling vibration time-history data and spectral characteristics are monitored and analyzed, and the results reveal the following: (1) The vibration response of adjacent piles caused by shield tunneling follows a power-law or exponential decay pattern as the pile-to-tunnel distance increases, with less significant attenuation at the pile top and more pronounced attenuation at the pile bottom and at the depth corresponding to the tunnel. (2) Based on different pile-to-tunnel distances, the tunneling influence range is classified into four categories: strong influence (<3 m), moderately strong influence (3－9 m), moderately weak influence (9－12 m), and weak influence (>12 m). (3) As the pile-to-tunnel distance increases, the high-frequency components of the vibration signals gradually diminish, while low-frequency components propagate further, still inducing vibrations in the pile. (4) Over 90% of the shield tunneling vibration energy is concentrated in the 0－64 Hz range, with low-frequency vibrations exerting a more significant impact on structures.

Key words: hard rock strata, shield tunnel, construction vibration, discrete element method-finite difference coupling, pile-tunnel spacing, dynamic response