| 摘要 |
PURPOSE:To improve the execution efficiency by setting the reference outbreak quantity, detecting the outbreak quantities, bending a leading pipe in the prescribed direction in reference to the compared result with the reference outbreak quantity, or bending a head section in the opposite direction to the prescribed direction, then bending it. CONSTITUTION:Outbreak quantities L5, L6 which are gaps between the outer diameter of a leading pipe 10 and a tunnel inner face 7 generated by an outbreak cutter 12 protruded from the outer diameter of the leading pipe 10 are measured by four outbreak quantity sensors 31 respectively, and the average value of four quantities is grasped as the outbreak quantity L. When outbreak quantity L > reference outbreak quantity Lo, a rocking cylinder 21 is rocked, the direction of a head section 1 is bent in the opposite direction by about 180 deg. to the correction direction, then the tip outer periphery section 2a of a rock section 2 is located on the correction direction side of the tunnel inner face 7. The rocking cylinder 21 is rocked while the head section 1 is rotated, the head section l is bent in the correction direction, and the head section 1 is propelled in the correction direction while excavating the ground. The direction can be correctly changed. |
