SECTION MEASURING APPARATUS FOR TUNNEL

PURPOSE:To enable accurate and quick measurement of the section of a tunnel over a wide range in the direction of excavation without moving a measuring device, by providing a mirror for projecting a laser light in a wide range of angle and a CCD camera. CONSTITUTION:A laser light 7 emitted from a laser oscillator 6 is reflected with a mirror 8 to project at a specified angle phi of depression or elevation in the direction of laser projection line 12 and generates a light spot 30 on the section 26 of a tunnel. The center line 13 of a CCD camera 13 is perpendicu lar to the laser light 7 and the camera 13 has a view angle thetaa corresponding to the length (n) of the light receiving surface 16. The segment between intersections 31a and 32a on the section 26 corresponds to the measuring range in the direction of excavating the tunnel 30 and the existence of the light spot 30 in the range enables the measurement of the section thereof. Here, the reflected laser light 35 is incident into the camera at the incident angle theta to be received at the receiving point on the light receiving surface 16 and thus, the measurement of the tunnel section can be done without moving the measur ing device.