Effects of the excavation of deep foundation pits on adjacent approach bridges: a case study of Nanjing Yangtze River Bridge

This study investigated a typical case of the deep foundation pit excavation influence on the pier deformation and structure safety of an adjacent double-curved arch bridge. The project is located at the Nanjing Yangtze River Bridge Station of Metro Line S8. Based on monitoring data, a relative displacement model for bridge piers was established. The deformation influence coefficients which taking into account distance and excavation depth were proposed. Impact zones were derived from the locations of monitoring points, with each zone classified according to the influence coefficient. Crack statistics were compiled for the bridge in the aftermath of foundation pit construction. The results indicate that the crack distribution corresponded with the impact zone grade classification. This case study provides significant reference points and guidelines for the protection of the double-curved arch bridge while offering indispensable data support for similar future efforts.