The Close Proximity Impact of a Newly Constructed Large Cross-Section Twin-Arch Tunnel Crossing an Existing Tunnel

With the Xinsen Avenue Tunnel Project in Chongqing Gaoxin District as the research context, this study investigates the degree of impact on an existing tunnel resulting from the construction of a new twin-arch tunnel that crosses over it. Utilizing finite element analysis methods, the study explores the displacement and stress variation patterns in the existing tunnel following the construction of the new tunnel, considering different clearances, crossing angles, and rock mass grade factors. Additionally, based on a composite discernment criterion involving additional stress and additional displacement, this study establishes longitudinal and transverse impact zones for intersecting tunnels. The research findings reveal that in terms of longitudinal impact, the clearance factor exerts a more substantial influence compared to rock mass grade and crossing angle factors. Regarding transverse impact, the area affected by parallel undercrossing is greater than that of parallel overcrossing, and the impact area is minimized when the new and existing tunnels are in a horizontally side-by-side configuration. The study's conclusions provide a theoretical basis and practical reference for the control of construction in similar large cross-section tunnel intersections.