This paper describes a new single-unit underground radar for detecting underground buried pipes. The pipe depth can be calculated from the hyperbolic shape in the cross-sectional image of radar echoes. The edge contour of the image is extracted, and the buried depth is judged from the similarity between the extracted hyperbolic curve and the theoretical curve. A suitable amplification rate is estimated by choosing the best image from numerous cross-sectional images formed during one antenna movement repeated at different amplification rates. The best image has few pixels corresponding to weak and saturated signals. The new radar is very compact, so it can be operated by one person. Objects buried up to 2.0m deep can be detected.

This paper describes a load carrying test for a concrete pipe designed to study the effectiveness of distributed strain measurement using an optical fiber sensor. We performed a load carrying test on a concrete pipe and attempted to detect the distributed strain inside it using an optical fiber sensor mounted inside the pipe. We confirmed that it was possible to detect the strain in a concrete structure by using an optical fiber sensor after a crack had occurred on the concrete surface. This paper shows that measurement using the optical fiber sensor was effective despite great changes in the strain conditions of the measured object over a short distance.