| 摘要 |
<p>PURPOSE:To carry out efficient excavation in accordance with the degree of hardness of natural ground by composing cutter bits for a shield main body of two types of bits; one for normal rotation and the other for reverse rotation, and by making an intermediary member for supporting of the bits supported in a way capable of swinging and advancing and retreating. CONSTITUTION:When a shield type tunnel boring machine equipped with a shield main body 10 and rotary cutter heads 12 is used for excavation, oil pres sure is supplied into an oil chamber on the push side of a cylinder 54 for a moving means 48 that moves a supporting means 24, and thereby the supporting means 24 is moved in proportion to the degree of hardness of natural ground to be bored to adjust the length of projection of cutter bits 38 from the front 21 of face plates 20. With the rotary cutter heads 12 rotated while the shield main body 10 is being moved, the cutter bits 38 are swung through an intermedi ary means 22, making bits 39a cut into the natural ground. Reaction force produced in the excavation is borne with the face plates 20 and members 26. Thereby, the reaction force can be reduced.</p> |
