| 摘要 |
PURPOSE:To make execution of work easy by a method wherein sensor heads and reflecting boards are installed on both sides of a form timbering and on fixed points corresponding to them, and displacements measured with the above- mentioned instruments are displayed and concrete is placed according to the displayed displacements. CONSTITUTION:Sensor head 10, 10A, numbered five in total, are fixed to two positions on the underside on both the right and the left sides of a gantry 5 and to a position on the gable side of a tunnel. Reflecting boards 11, 11A are then provided, facing each of the sensor heads, and are fixed to the ground GL. Laser beams emitted from the sensor heads 10, 10A are reflected with the reflecting boards 11, 11A and the distance between each of the sensor heads and each of the reflecting boards is measured out of the time required for returning of the reflected beam. According to displacements confirmed by the above-mentioned measurement, quantity of concrete to be placed and the measured displacement of a form timbering are shown on a CRT, and speed and positions for concrete placement is then adjusted by visual observation of the display so that the displacements become roughly identical on both the right and the left sides of the form timbering. |
