After 11 months of tunneling and overcoming geological challenges, bored excavation for the 3.87km tunnel of Lot 1011-3, Shenzhen Metro Line 10 using a Double Shield 6.5m TBM manufactured by CREG is complete. The breakthrough took place on 14 January and it is the first double shield TBM used for Shenzhen metro.

Shenzhen Metro Line 10 is 29.54km long with 24 stations and the 5.36km Lot 1011-3 which the machine served was awarded toCRTG-3.
 

The overburden of the TBM driven tunnel ranges from 16m to 200m. Geological conditions presented significant demands for the Double Shield TBM. The tunnel is below Xiamen-Shenzhen Railway and Dongjiang Water source projects. Added to this are 15 fractured zones and 2 sites of faults along the drive. Throughout the tunneling course, the machine has encountered SW granite (RQD up to 127 MPa), water and slurry ingress, high temperature in tunnel, frequent cutter intervention, long-distance drive and difficult ventilation. Despite of the complex geological and hydrogeological conditions, the machine achieved the best advance of 15m per shift, 24m per day and 423m per month. 

The TBM drive is completed to high quality and within program. Behind this success is the sound collaboration between CREG and CRTG-3 which worked closely on the efficient rock-breaking, wear-resistant, anti-blogging and small-curve designs of the machine to cope with the anticipated challenges.