Abstract:

 Focusing on the challenge of boring in cobblecontained ground, the authors make feasibility study on application of open shield in construction of Beijing Metro tunnels in cobblecontained ground in terms of geological adaptability, structural maintainability, performance, advantages in coping with large cobbles and boulders, construction safety and quality and boring speed. The authors propose the design and boring techniques of open shield for Beijing Metro works. Regarding boring in cobblecontained ground, the authors make comparison and contrast between EPB shield and open shield in terms of boring speed, economical index and comprehensive performance. The authors conclude that it is worth to take open shield into consideration in the selection of proper shields for cobblecontained ground.

Key words: open shield, shield design, shield boring technology, Metro tunnel, feasibility study