Numerical Investigation of Bored Tunnelling Effects on Pile-Supported Superstructures

Tunnelling in urban environments can significantly affect existing buried structures such as pile foundations. However, the current understanding of how tunnelling-induced ground movements influence the stability and serviceability of piles remains limited. This knowledge gap presents potential risks that must be addressed during tunnel design and construction. This study investigates the impact of adjacent tunnelling on long piles supported superstructure through a series of three-dimensional numerical analyses. The numerical model was validated using data from a well-documented case study. The analysis considered four tunnel depths and four horizontal clearances, along with varying pile lengths and tunnel volume losses. Key responses of the pile, including induced axial force, bending moment, vertical displacement, and safety factor were examined. From these results, a safety zone was proposed based on an integrated interpretation of the pile responses under different tunnelling scenarios. The findings indicate that for piles ranging from 40 to 50 metres in length, the safety clearance can be classified into four relative depth zones based on tunnel depth. For piles exceeding 50 metres, the influence zone can be grouped into two depth categories. These results offer valuable guidance for geotechnical engineers involved in tunnel alignment and risk mitigation when working near long pile foundations. Given the increasing utilisation of underground space in densely populated areas, the insights from this research contribute to more informed, effective, and sustainable urban planning and infrastructure development strategies.