Abstract: With the increasing utilization of the underground space in urban areas, studying the deformation characteristics of the deep excavation above the existing tunnels is of significant importance for the construction safety and the support design. Based on the Tianmu Mountain Road transformation project, the surface settlement of both the excavated area and adjacent excavations were analyzed during the excavation process, and the general rules of settlement deformation of the underlying existing tunnel were monitored and obtained. The results showed that a reasonable supporting structure can effectively control the settlement deformation around the foundation pit, and during the reinforcement stage above the foundation pit, the existing tunnel below was significantly affected, resulting in significant settlement deformation. However, the deformation during the construction stage after reinforced was relatively small. The finding of this study has reference value for construction design and risk control.

Key words: Existing Tunnel, Excavation Deformation, Surrounding Settlement, Deformation Characteristic Analysis