Influence of Deep Excavations on Nearby Existing Tunnels

InShanghai,anumberofnewundergroundpassagesarebeingconstructed,oftenrequiringdeepexcavations.Whentheexcavations areinthevicinityof existingtunnels,it isnecessarytoassesstheinfluenceof theseexcavations onexistingtunnelssuchasdisplacementsofthe lining and additional loads on the lining. This paper presents a finite-element parametric study of tunnel behavior caused by nearby deep ex- cavation. This study investigates the effects of several parameters that may affect the tunnel response. These parameters are: Relative position of the tunnel with respect to the excavation, tunnel diameter, excavation dimensions, and tunnel protection measures. The results reveal that the influence of the excavation on the underlying tunnel is significant in a range of ∼53excavation width measured along the tunnel axis; unloading further than 10 m away from the axis of the tunnel has little effect on the tunnel structure. Based on the study in this paper a better understanding of the interaction between deep excavations and tunnels will be obtained. DOI: 10.1061/(ASCE)GM.1943- 5622.0000188. © 2013 American Society of Civil Engineers. CE Database subject headings: Finite element method; Excavation; Soft soils; Tunnels.