Influence of Metro Tunnel Excavation on Deformation of Existing Pedestrian Underpass in Changzhou Railway Station Platform

In order to predict the impact of Changzhou Metro Line 1 passing through the pedestrian underpass of Changzhou Station in Shanghai-Nanjing Intercity Railway, FLAC3D software is used to simulate the excavation of the left and right subway tunnel lines step by step. The influences of existing and non-exiting pedestrian underpass on subsurface settlement are compared, and the deformation and stress distribution of the pedestrian underpass are analyzed. Additionally, the numerical results are verified by filed monitoring. The calculation and monitoring results show that the existence of the pedestrian underpass causes a relatively obvious “barrier” effect, which makes the vertical displacement changes with increasing of depth, and consequently causes the uneven vertical displacement. The tunnel excavation mainly causes the inclination of the pedestrian underpass, the floor deformation of the escalator channel, and the deformation difference occurs at the interface between escalator channel and pedestrian underpass; the existence of tunnel has little influence on the stress change of the pedestrian underpass. However, in order to protect from the concentration of stress, it is necessary to focus on monitoring the place where has a large stress during construction, such as, the right interface between pedestrian underpass and escalator channel, and the right exit of escalator channel.