Monitoring and Numerical Analysis of Soil Displacements Due to Excavation of the Exit of Liuyang River Tunnel

Liuyang River tunnel, one of the longest tunnels in Wuhan-Guangshou railway passenger dedicated line, encountered low overburden, weak rock and crowded surface buildings in exit. If incorrect excavation method was tacked, it will cause serious damages to the environment and buildings. As it belongs to large-section excavation, for which cross section area surpasses 150 m(squared). In order to avoid oversize subsidence by excavation of the large cross section, field monitoring including stratum displacement and three dimensional deformations were carried out. Combined field monitoring with numerical analysis, stratum displacement distributed rule in large cross section tunnel excavation process was observed, which showed that the construction process is safe.