Abstract: The present invention discloses a system and a method for transmitting data in a shield machine and for calculating the filling amount of a void by detecting the distance to the natural ground. The system and the method are capable of transmitting analogue signals or signals of relatively high frequencies with reliability, enabling an unskilled operator to accurately detect buried articles and accurately carry out the back-filling work. Therefore, an optical rotary joint (100) is disposed between a rotary cutter head (10) and a non-rotary shield body (2) to count time taken to detect the peak value of a reflected signal larger than a standard value or time taken to detect the zero cross position present prior to the peak value. In accordance with the counted time, the distance between the antenna and the natural ground is calculated and displayed. Then, the void volume is calculated in accordance with the distance so that a target value of the back-filling amount is set.

Abstract: Magnetic field producers are disposed either at the leading portion of an underground excavator or at a reference position in front of the underground excavator. The magnetic field producers can be constituted by a plurality of rectangular loops disposed to run parallel to one another and to overlap one another. The rectangular loops can be individually excited sequentially or they can be simultaneously excited at different frequencies. The magnetic field produced by a magnetic field producer can be detected by a first magnetic field detector and by a second magnetic field detector disposed to the rear of the first magnetic field detector so that the inclination angle of the underground excavator can be obtained from the difference between the positions of the two detectors. A loop of a magnetic field producing cable can be covered by a non-magnetic metal member so that wear and disconnection are prevented.

Abstract: A method and an apparatus for performing measurement by a resistivity method in order to detect the thickness of a sludge layer on the outer periphery of a shield machine. A Wenner electrode row (14) on the outer periphery of the machine is used to measure reference resistivities to thereby detect certain resistivities in the depth direction of the natural ground and the sludge layer thickness. At the same time, a dipole electrode row (16) is used to measure voltage distributions in the depth direction of the natural ground and in the direction of the arrangement of the electrodes. The ratios of the values measured by the measurement dipole electrodes to those measured by the reference Wenner electrodes are calculated, and their distribution is charted. When mutually equal values in the distribution map are connected together by continuous curves, a contour-pattern image is obtained, which enables a configuration of the collapse of natural ground to be determined.

Abstract: In the present invention, a first and a second projector means projecting rotating laser beams rotating at a predetermined period are disposed at two predetermined fixed points, respectively. A first, a second and a third photodetection means are disposed on a moving body to detect the photodetection timings with which laser beams are detected, and to detect photodetection height positions of the rotating laser beams. The rotating angles of the two rotating laser beams from the reference azimuth are calculated on the basis of the outputs from the first, second and third photodetection means, and the positions and heights of the respective photodetection means are calculated from these data. Thus are the position and attitude angle of the moving body are measured with high accuracy, and these data are displayed on a real-time basis.