| 摘要 |
PURPOSE:To precisely and readily form an arch-shaped tunnel section without uneven lines while reducing evil influences against the surrounding environment due to noise, vibration, dust, etc. CONSTITUTION:A working area is provided with a working space 2 formed at the front and rear sides of an expected position for a tunnel and counterposed against the tunnel arch, a communicating drift 1 formed under the tunnel arch to communicated with the front and the rear working spaces 2, and a pierced hole 2a formed on the arched inner peripheral line X of the tunnel arch to communicate with the front and the rear working spaces 2. Support arms 3a having nearly the same length of the radius of rotation with the radius of curvature of the inner peripheral line X are arranged respectively in both working spaces 2. The expected position E1 for excavation is surrounded while supporting a wire saw 6 by support pulley 7 set at the front ends of respective support arms 3a and while tensing the wire saw 6 hooked to form a loop and endlessly driving it to rotate between the support arms 3a. The wire saw 6 is moved along the inner peripheral line X and hence the expected position E1 for excavation is separated from the surrounding rock E to form an arch. |
