Muddy water shield excavator and its excavation method

摘要

PROBLEM TO BE SOLVED: To surely mitigate a fluctuation of muddy water pressure in a cutter chamber without being affected by a fluctuation of water level in an auxiliary chamber provided in a muddy water type shield excavator. SOLUTION: When compressed air is constantly supplied from a receiver tank to an auxiliary chamber and the detection result of an electrode sensor is the upper limit water level, a first valve V1, a second valve V2, and a fifth valve Open only V5 and the sixth valve V6, drain mud until the inside of the auxiliary chamber reaches the reference water level L3, and start digging. If the detection result of the electrode sensor is the reference water level, the first valve When only V1, the second valve V2 and the sixth valve V6 are opened to perform excavation without supplying and draining mud in the auxiliary chamber, and the detection result of the electrode sensor S is the lower limit water level, the first Only the valve V1, the second valve V2, the fourth valve V4, and the sixth valve V6 are opened, and mud is supplied until the inside of the auxiliary chamber reaches the reference water level to start excavation. [Selection diagram] Fig. 5