| 摘要 |
PROBLEM TO BE SOLVED: To discharge excavated earth and sand from a working face by holding earth pressure to the working face while preventing back flow in an earth pressure shield construction method. SOLUTION: A jet ejector 5 is connected to a flow-down port of a muddy water chamber 2 provided at a discharge port of a screw conveyor 39 in an earth pressure shield construction method. The jet ejector 5 has a cavity 10 in which a nozzle 7 and a Venturi tube 9 are separated directly below the flow-down port of the muddy water chamber. A feed water pipe 20 connected to a feed water tank is connected to the upper part of a circulation adjusting tank 11, and a water pipe 21 connected to the vicinity of the bottom part of the circulation adjusting tank is connected to the water supply port of the jet ejector 5. The flowing earth and sand in the muddy water chamber 2 are thereby discharged by jet water from the nozzle 7 and transferred to the discharge side via the Venturi tube 9, and the pressure of the circulation adjusting tank 1 is regulated by the feed water pump to hold the pressure of the muddy water chamber to thereby prevent back flow to the working face.
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