Abstract:

In order to solve the rectangular shield tunnelinginduced cutterhead cutter drop, screw conveyor choked and cutterhead blocked and broken down, the obstacle cleaning technologies by chamber opening are summarized. Some conclusions are drawn as follows: 1) The boulders and abandoned steel pipe which block the cutterhead are cleaned successfully by opening chamber under atmospheric condition after inspection of the stability of tunnel face under compressed air. 2) The obstacles around shallowburied shield tunnel should be cleaned before shield arriving so as to avoid serious risks and reduce the pecuniary cost. 3) A full consideration of possible obstacles encountered and related countermeasures should be carried out before shield tunneling, including prearrangement of compressed air team and necessary equipment for cutterhead replacement.

Key words: large crosssection rectangular shield, obstacle, chamber opening, trenchless underpass