| 摘要 |
PURPOSE:To enhance the accuracy of sensing by discharging a measuring bullet fitted with a wire toward a natural ground from a shield excavating machine side, measuring the length of the wire, and judging whether there is any collapse in the natural ground. CONSTITUTION:Compressed air is supplied to a piping 14 for discharging a measuring bullet provided on a shield body A, and the bullet 11 fitted with a wire 7 is aimed at the natural ground at a high speed. A wire reel 6 is rewound by a motor 4 so that the wire 7 is stretched, and the drawn-out wire length L is measured by a wire length measuring device 21, and judgement is passed whether any collapse exists ahead. Accordingly the measuring bullet can reach the excavation surface upon piercing the stagnant such as muddy water, and real fact of any existence of collapse can be known without generation of error. |
