Abstract
The usual way to set up a telegraph pole is to use an earth auger machine. However, since the locations of underground utility pipes and cables often are not accurately recorded, buried objects are often damaged during drilling. Although electromagnetic induction and electromagnetic waves have been used for sensing underground objects non-destructively, the former cannot be used for non-metallic objects, and the latter produces radar images that are difficult to interpret.
We have studied a method of sensing underground objects while drilling in earth based on vibration analysis. In order to measure the vibration signal, we attached a toothed cylindrical casing with an acceleration sensor mounted inside to the tip of the auger drill. The results obtained in this studies are as follows:
1) Underground objects could be detected by observing the change in the acceleration signal upon contact.
2) Buried pipes could be distinguished from other objects (e.g. stones and pebbles) by analyzing the spectrum of the acceleration signal.
3) We have developed a underground object sensing system for earth auger machine. And it has been confirmed that the system is effective for actual field use.
