Abstract: The excavation of the communication gallery is a key process in the construction of subway tunnels. This paper presents a case history of a communication gallery construction for a subway tunnel. The deformation of the rock mass surrounding the tunnel in the excavation process was numerically simulated by using Midas GTX NX software based on the actual construction sequence and calibrated with construction monitoring data. Based on the analytical and monitoring results, the following conclusions could be made: In the process of communication gallery excavation, because of stress concentration, maximum settlement could be observed at the joint of main tunnel and communication gallery. This area should be monitored. The joint between the longitudinal side of the pump house and the shielded tunnel supporting area is the main lateral deflection zone. Large surface subsidence will be occurred in area within 15 meters along the center alignment of the communication gallery.

Key words: communication gallery, midas/GTX NX, surface subsidence, monitoring analysis