Three dimensional numerical investigation on the effect of bridge construction on existing tunnel

This paper presents the results of a three-dimensional (3D) numerical investigation into the effect of pile-supported bridge construction on an existing tunnel. A number of bridge construction cases were developed with due consideration of urban tunneling situations aiming at identifying interaction mechanism between the bridge construction and the tunnel lining. In the 3D model, various components of the tunnel as well as the bridge including piers, piles, and pile caps are realistically modeled. Also modeled is the pile-ground interface to allow for possible slip between the piles and the ground. The results of the analysis revealed among other things that the effect of pile-supported bridge construction on a tunnel may be ignored when the clearance between the pile tip and the tunnel lining exceeds 1.0D and 0.5D for centrally and eccentrically loaded tunnels, respectively, for the cases considered in this study. Practical implications of the findings are discussed.