Abstract:

Guomao Station～Laojie Station mined running tunnel on phase 1 of Shenzhen Metro is designed as a singletube overlapped twostorey tunnel. It is the first time in China that such a special tunnel structure has been adopted in Metro works. The tunnel is excavated by means of heading/bench excavation method, which includes 4 steps. In the paper, the pattern of the surface subsidence caused by tunnel construction, such as the scope of the surface subsidence caused by overlapped tunnel construction, the magnitude of the surface subsidence, the regularity and features of the surface subsidence as a function of time, is analyzed on basis of the monitoring data. The major factors influencing the surface subsidence pattern, such as the geological conditions and the bench lengths, are also thoroughly analyzed and some subsidencecontrolling countermeasures are recommended in the paper.