为研究动荷载对临近桥梁微型桩深基坑开挖稳定性的影响,以中国“一带一路”重点贡献项目格鲁吉亚E60高速公路Ubisa-Shorapani(F3)标段工程为主要依托,通过数值模拟分析列车荷载对基坑土体、支护结构内力及变形影响,并将数值计算结果与现场监测数据对比分析。结果表明:相对于无列车荷载,考虑列车荷载作用下近侧桩体最大位移和土体最大沉降分别增大14.5%、20%,基坑整体安全系数减小0.1,在开挖过程中应充分考虑列车荷载对基坑稳定性的影响。不同列车荷载施加方式下,首道支撑所受影响显著,各道支撑轴力变化幅度随开挖从上到下逐渐减小。列车荷载距离基坑边界5 m时近列车侧土体最大沉降比20 m条件下增大3.61 mm,且当距离为20 m时土体沉降几乎不受列车荷载影响,基坑稳定性较好。动荷载时速为120 km/h、距离为5 m情况下桩体内力受荷载影响较大,弯矩及最大弯矩位置深度随荷载距离减小逐渐增大,最大弯矩相比无列车荷载时增大210 kN·m。

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.