Remote Acoustical Reconstruction of Cave and Pipe Geometries

Soldiers and rescue workers are frequently asked to enter the underground passages of caves, tunnels, and piping (C/T/P) systems. The layout is unknown, increasing the danger. A system that would provide a map of the geometry could be very helpful in such cases. We propose to determine the feasibility of a system based on reflected sound waves that can be placed at the opening to the C/T/P complex and provide such a map. The feasibility of such a system has been shown for medical applications in which the passage cross-sectional area vs. distance can be mapped. Our own measurements of the reflected waves in a laboratory table top experiment provide additional confirmation of the proposed method. It is the goal of the proposed research to 1) demonstrate the basic performance through laboratory studies, 2) test certain enhancements expected to improve the performance, and 3) to prepare for a system suitable for measurements in a field situation.