| 摘要 |
PURPOSE:To certainly crush reinforcing bars inside of a building frame of an existing pipe at the time of wrecking, expansing and changing the existing pipe made of reinforced concrete. CONSTITUTION:A second cutter head 80 sharpened toward an inner peripheral margin 80a on the front surface side is provided inward of a first cutter head 10 sharpened toward an outer peripheral margin 10e on the front surface side, and a debris collecting region 25 is formed cylindrically in a shape to contract toward the rear side in the shield propelling direction by digging surfaces 10g, 80g of the first and second cutter heads 10, 80. Additionally, a wrecked matter transfer cavity 26 is provided between the first and second cutter heads 10, 80 in a form to communicate the debris collecting region 26 and a digging chamber 10c. A building frame 31 of an obsolete pipe 3 is further strongly crushed and treated by the wrecked matter transfer cavity 26 after primarily crushing it by rotational drive of the first and second cutter heads 10, 80 by way of taking it in the debris collecting region 25. |
