Abstract: To investigate the impact of dynamic loading on the stability of adjacent bridges with micro-pile deep foundation pits, this study focuses primarily on the Ubisa-Shorapani (F3) section of Georgia E60 Expressway, which is a significant project contributing to China’s “Belt and Road” initiative. Numerical simulation is employed to analyze the effects of train loads on the foundation pit soil as well as the internal forces and deformation of the supporting structure. The results obtained from the numerical calculations are then compared with the data collected from on-site monitoring. The findings reveal that under the influence of train loads, the maximum displacement of pile near the train side and the maximum settlement of the soil increase by approximately 14.5% and 20%, respectively. Moreover, the overall safety factor of the foundation pit decreases by 0.1. Therefore, it is crucial to fully consider the impact of train loads on the stability of the foundation pit during the excavation process. The initial support is particularly affected by different loading modes, and the range of change in axial force for each support gradually decreases as the excavation progresses from top to bottom. When the train load is positioned 5 m away from the boundary of the foundation pit, the settlement of the soil near the train side is 3.61 mm greater compared to a load distance of 20 m. At a load distance of 20 m, soil settlement experiences minimal influence from the train load, resulting in improved stability of the foundation pit. The dynamic load exerted by the train greatly affects the internal forces of the neighboring pile. The magnitude of bending moment and the depth at which the maximum bending moment occurs increase gradually as the load distance decreases. Specifically, when the dynamic load speed is set at 120 km/h and the distance is 5 m, the pile experiences significant load-induced effects. The bending moment increases by 210 kN·m, and the depth at which the maximum bending moment occurs rises compared to the scenario without train load.

Key words: deep foundation, micro-pile, nemerical simulation, dynamic load, horizontal displacement, surface subsidence, axial force of support, bending moment of pile shaft, safety factor