Field Test of Roof-protected Shield Method which Provides Safe Tunneling at Extreme Shallow Depth |
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Nobuaki KOBAYASHI, Koutarou KOBAYASHI, Tatsufumi HIROSUE, Ryo TAKASHIMA*1 and Takashi NAKANE*2 |
The Roof-Protected Shield machine has a long protective "roof" extended from the excavation head. This roof prevents ground from loosening, constrains the ground deformation and enabled safe tunneling at extreme shallow depth. It has the same mechanisms as the earth pressure balance type shield method in order to protect against ground collapse at extreme shallow depth. These mechanisms consist of excavation, adjustment of earth pressure, and control of discharge of ground. We have carried out demonstration tests in order to prove that the earth pressure is controllable with high precision with the mechanism in different from and scale from the conventional shield machine. The experimental outline, and the design method of the management criteria of the earth pressure are described in this report. |
keywords: |
shallow depth, grade separation, underpass, traffic jam, tunneling near existing underground facilities, shield machine |