Construction method of earth cabin back filling and cabin entering operation during earth pressure shielding

The invention discloses a construction method of earth cabin back filling and cabin entering operation during earth pressure shielding. The construction method comprises the following steps: (1) injecting bentonite slurry outside the casing of a shield machine; (2) injecting polyurethane outside the body of a shield to form a seal ring; (3) injecting two-liquid slurry outside a tube piece to form a seal ring; (4) replacing muck in an earth cabin with bentonite, and carrying out muck replacement through the cooperation of the a bentonite injection system and a spiral conveyer; (5) carrying out pressure injecting on low, middle and high-strength cement bentonite mortar slurry, and allowing the bentonite slurry in the earth cabin to form cumulates with certain strength; (6) injecting slurry to a cutting ring of the shield machine and the top of a cutter head; (7) carrying out cabin entering operation by constructors; and (8) closing an earth cabin door after cutter replacement is completed, injecting and back-filling bentonite to the earth cabin to establish an earth pressure balanced mode to restore tunneling. The construction method disclosed the invention breaks through the difficulty of cabin entering operation below a special unstable formation and the difficulty of cabin entering operation under a building during shielding, and has the characteristics of high efficiency, strong operability and the like.