| 摘要 |
PROBLEM TO BE SOLVED: To reduce using quantity of skid by automatically controlling injection quantity of a first skid in proportion to an excavating speed, and injecting a second skid into the outer periphery of propelling pipes having strain quantity exceeding a specified value. SOLUTION: A rear end side shield cylinder 3 is connected to a tip side shield cylinder 2 having a cutter head 4 on the tip, and propelling pipes 11, 12 are connected via a first skid injection device 10 to be pressed by a jack 32 in a departing shaft to advance boring. Skid supply quantity to the first skid injection device 10 from skid tanks 23, 25 is automatically controlled by a computer 34 in proportion to a boring advancing speed detected by a speed detecting device 33. A strain detecting device and a second skid supply device 27 are arranged in the respective propelling pipes 11, 12, and when detected strain quantity exceeds a specified value, a skid is supplied to the second skid supply device 27 from a skid tank 31 to reduce friction of the respective propelling pipes 11, 12 to thereby prevent injection of an excess skid to reduce using quantity of skid.
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