TBM Selection Optimization and Tunneling Parameter Control in Complex Offshore Strata for Urban Rail Transit

Abstract

[Objective] In order to improve the formation adaptability of the tunnel boring machine (shorten as TBM) and solve the problem of TBM selection for the west extension section of Qingdao Metro Line 2 (hereinafter referred to as Line 2) in the complex formation offshore, it is necessary to optimize TBM selection and control tunneling parameters. [Method] From the aspects of geological condition adaptability, construction flexibility and excavation efficiency, the TBM types are comprehensively compared and the one suitable for hard rock excavation is selected. In view of the engineering difficulties in the TBM tunneling section of Line 2, such as crossing fracture zone, insufficient starting space, small curvature radius construction and lack of lifting conditions, the TBM is optimized. The range of parameter values including thrust, torque, cutter speed and net tunneling rate of double-shield TBM under different grades of wall rock are determined. [Result & Conclusion] After comprehensive comparison, DSUC type double shield TBM is selected for the construction of Line 2 west extension section in complex offshore strata. This type of TBM has good formation adaptability and flexible support methods. By optimizing cutter head, shield body and back-up train design, improving the starting, disassembling and small curvature radius construction scheme, and improving the advance reinforcement and guidance system, TBM application becomes more economical and reasonable. When the TBM advances in the medium hard rock formation, the thrust and torque can be properly improved to increase the net tunneling rate. The tunneling parameters should be strictly controlled to reduce the disturbance to the palm surface when the TBM passes through fault fracture zone.

Keywords

• urban rail transit
• tbm selection
• tunneling parameter
• complex offshore strata