| 摘要 |
PURPOSE:To improve the economical efficiency by making the eccentric quantity of a cutter head shorter than the eccentric quantity determined by the triangle of Reuleaux, increasing the radius of curvature of the corner section of a tunnel as the center section of the side of the excavated rectangular tunnel is expanded to the outside, and improving the structural strength of a segment itself. CONSTITUTION:A cylindrical rotor is rotatably provided in front of a shield main body 1 with the prescribed eccentric quantity epsilon, and a rotary shaft body is rotatably arranged on the cylindrical rotor. A cutter head 11 radially protruded with three arm-like cutters 10 having the same length respectively at the same angle is fitted to the front end section of the rotary shaft body, and the cylindrical rotor is rotated at the speed of three times in the opposite direction to the rotating direction of the rotary shaft body. The eccentric quantity of the cylindrical rotor is set to a distance shorter than [(L/2)cos30 deg.-(L/2)], where L indicates the linear distance between the tips of the arm-like cutters. |
