Abstract:

The Qiushuishan tunnel, super shallow buried, crosses underneath toll station of Shenzhen Bao’an International AirportHeao Highway in Shenzhen in waterrich backfill soil. The traffic on the ground is heavy and the construction deformation is difficult. The ground settlement during tunnel construction is analyzed by software FLAC3D. And then the ground deformation causes are determined and the time of each construction phase and bench data are studied and analyzed. Finally, a series of technologies, i.e. doubleside drift and micro bench method, arch feet reinforcement, working face closure, groundwater treatment, control of excavation and support process and monitoring, are adopted. The crown top settlement is controlled within 45.6 mm and ground surface settlement is controlled within 184 mm, which have guaranteed the safety of the tunnel and vehicle on the ground.

Key words: super shallowburied mined tunnel, crossing underneath highway, doubleside drift and micro bench method, 3D numerical simulation, deformation control