Study of construction technology for subsurface excavation of metro tunnel group in complex environment

The lines No.5 and No.7 of Shenzhen metro are designed as double-tube overlapped two-storey tunnels from Tai'an Station to Yijing Station. The upper and lower tunnels are staggered for a certain distance and then excavated synchronously in construction process. Due to the complex environment and relatively poor geological condition, advanced small pipes grouting with cement-water glass(CS) is supplemented for water-seal and reinforcement. According to different cross-sections of tunnels, reasonable construction technologies are selected to reduce the disturbance to soils. These measures improve the construction environment effectively, ensures the safe construction of the project, and shortens the construction period greatly. This project can porvide reference values to similar domestic projects.