| 摘要 |
PROBLEM TO BE SOLVED: To provide a tunnel construction method for constructing a portal or box-type shell by rectangular propelling boxes in a manner eliminating unexcavated areas and without carrying out unreasonable press-fitting. SOLUTION: The tunnel construction method is composed of a normal propelling step and a thrust propelling step. In the normal propelling step, propulsion is carried out by a multi-axial propeller 2 which has an excavating cross section of a half-cut ellipse that is a combination of a half circle and a rectangle, a half-circular propelling box 3 for propelling a half-circular section 21 of the multi-axial propeller 2, and a rectangular propelling box 4 for propelling a rectangular section 22 of the multi-axial propeller 2. In the thrust propelling step, propulsion is carried out by the multi-axial propeller 2 which is shifted from a propulsion starting location in the former step toward the half-circular section 21 by a predetermined pitch, the rectangular propelling box 4 which is in a phase adjacent to the rectangular propelling box 4 embedded in the former step and arranged on the rear of the multi-axial propeller 2, and the half-circular propelling box 3 which is arranged on the rear of the half-circular section 21 of the multi-axial propeller 2, and the propulsion is carried out while the half-circular propelling box 3 embedded in the former step is thrust. Thus the shell is constructed by repeatedly carrying out the thrust propelling step. COPYRIGHT: (C)2008,JPO&INPIT
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