OVERBREAK DEVICE CONTROLLING METHOD OF TUNNEL BORING MACHINE, AND ITS CONTROL DEVICE

PROBLEM TO BE SOLVED: To provide an overbreak device controlling method of a tunnel boring machine capable of simplifying the control of the stroke of an overbreak device and preventing the control delay in excavating various dissimilar sections, and its device. SOLUTION: When a spoke 3 is oscillated from a point A to a point D, an overbreak device 6 is expanded according to the inclination of the spoke 3 to excavate a horizontal part 9. When a tip of the overbreak device 6 reaches a switching point B, the expansion of the overbreak device 6 is stopped, and kept at a specified value, a corner part 7a is excavated by the oscillation of the spoke 3. When the tip reaches the switching point C, the overbreak device 6 is contracted according to the inclination of the spoke to excavate a vertical part 10.