3D Numerical Analysis of Construction Process for Tunnelling of Donghu Metro Station: Fid-Bau Portal

3D Numerical Analysis of Construction Process for Tunnelling of Donghu Metro Station

Li, Hongjian

The Donghu station of No.6 line of Guangzhou rail transit is divided two parts: the embedded excavation part and the open excavation part. The kilometer of the embedded excavation part is from k13+462.752 to k13+519.452. The tunnel crown is located 19 m below the ground surface. Soil stratums are mix-filled soil, alluvial deposit to flooded alluvial deposit, wholly-weathered rock of red strata, highly weathered rock of red strata, moderately weathered rock of red strata and slightly weathered rock of red strata from the top down. The largest span of tunnel is 20 m. Its largest height is 10.349 m. Because the tunnel has large span and section, the construction is very difficult. In order to control the surface settlement and ensure the security of tunnel, the Finite Element Analysis method is used to analyze the construction process and find the rationality of construction method and support system. A three-dimensional numerical simulation model analyzes the construction process of the tube pre-support and center drift method in Donghu station by FLAC-3D. The results indicate that the reinforced and construction method can ensure the safety of construction, and control the surface settlement. The final conclusions are two: (1) the surface settlement and displacement are small and the tunnel is steady in the construction process. (2) The main step of influencing the surface settlement and crown settlement are step I , step IV and removing of the temporary supporter. So the initial support must be installed in time and reinforced the supporter strength. The distance which is from working face to liner must be more than two times span of tunnel.