Method of supporting tunnel face during shield driving excavation - involves bulkhead with high level shuttered opening and vertical partition next to face forming air pocket in between

摘要

Buoyant plastics balls (11) are filled into the space (3) between the tunnel face (10) and the front shutter (5). An aqueous bentonite solution is injected through a pipe (8) into this space as supporting medium, and excavated material and water are dredged into the lower part of the air chamber (6) formed between the shutter and the bulkhead. From here the sludge is pumped to the rear through pipes (7). Compressed air injected into the chamber (6) forces the plastics balls and bentonite solution against the tunnel face through pressure against the shutter (5). A grill (14) allows sludge to pass but retains the plastics balls in position. ADVANTAGE - Effective support without excessive use of solution.