| 摘要 |
PURPOSE:To make it possible to correct a direction in the direction opposed to an inclination by taking advantage of the reaction force of a mud wall against the reaction force by controlling the inclination of an external pipe so that it is directed in the direction opposed to a corrected direction to make rotatable of an internal pipe and to make non-rotatable the external pipe, and driving both pipes forward simultaneously. CONSTITUTION:An underground excavator is constituted of an external pipe 1 and internal pipe 2, and an inclination 3 inclined to the end of the external pipe in the direction of an axis is provided to the external pipe 1. In the internal pipe 2, retract bits 6 are provided to the ends thereof so that they are capable of being housed in external pipes 7. In the event of straight excavation, both pipes are driven forward while rotating the external pipe 1 and internal pipe 2, and after the correction of a direction is controlled at the circumferential direction so that the inclination 3 of the external pipe 1 is inclined to the direction opposed to the corrected direction, both pipes are driven forward by making non-rotatable of the external pipe 1 while rotating the internal pipe 2. According to the construction, the inclination 3 of the external pipe 1 receives the reaction force of a mud wall, and the direction of the external pipe 1 as well as the internal pipe 2 is corrected to the direction opposed to the inclination 3. According to the constitution, the correction of an excavated direction can be carried out positively and efficiently. |
