3D numerical modulate analysis on metro overlapped tunnels

Based on the interval tunnels between Fenghuang Xincun and Sha Yuan metro stations in Guangzhou City, the construction effects of the overlapped tunnels are researched. 3D Finite Element Method is also adopted. The distribution of stratum deformation and crown raising displacement of the lower tunnel are analyzed. Axial force, moment and stress changing of the overlapped tunnels during the different construction stages are discussed. The results show us that: the ground surface settlement trough of the overlapped tunnels is symmetrical; the crown raising displacement of the lower tunnel caused by the construction of the up tunnel is about 4~6mm, and the total crown settlement is to decrease nearly 50% after the construction of the up tunnel; the changing of the inner force caused by the excavation is more complicated during the different construction stages, and the excavation of the up tunnel can obviously impact the lower tunnel that has already built, the adverse impact region locates in front of the working face 15m and back of that 20m. The conclusion is that lining inner force of the overlapped tunnel is favorable and endurable by the external load during the construction stage, and such design concept also can meet the requirement of the underground space´s sustainable development and utilization.