Abstract:

Jamming always occurs to EPB shield when tunneling in strata with largediameter boulders. As a result, STM063D1 open shield is developed. Technologies, including open mode excavation, supporting mode of “hatbrimtype shield body + retractable shield front + removable front plate”, and screw conveyor working under atmospheric pressure, have been used for the mentioned shield. The open shield has been successfully used in Phrase Ⅱ project of No. 6 Line of Beijing Metro. The tests of key parts and the tunneling practice show that, compared to EPB shield, the open shield is more suitable for sandy cobble ground with good selfsupport capability and containing almost no water. Open shield and related technologies are worth to be popularized in Beijing and other regions in China.

Key words: open shield, open working principle and structure, support, tunneling