Determining the location of buried plastic water pipes from measurements of ground surface vibration

‘Mapping the Underworld’ is a UK-based project, which aims to create a multi-sensor device that combines complementary technologies for remote buried utility service detection and location. One of the technologies to be incorporated in the device is low-frequency vibro-acoustics, and techniques for detecting buried infrastructure, in particular plastic water pipes, are being investigated. One of the proposed techniques involves excitation of the pipe at some known location with concurrent vibrational mapping of the ground surface in order to infer the location of the remainder of the pipe. In this paper, measurements made on a dedicated pipe rig are reported. Frequency response measurements relating vibrational velocity on the ground to the input excitation were acquired. Contour plots of the unwrapped phase revealed the location of the pipe to within 0.1-0.2 m. Magnitude contour plots revealed the excitation point and also the location of the pipe end. By examining the unwrapped phase gradients along a line above the pipe, it was possible to identify the wave-type within the pipe responsible for the ground surface vibration. Furthermore, changes in the ground surface phase speed computed using this method enabled the location of the end of the pipe to be confirmed

[1]  R. J. Pinnington,et al.  Externally Applied Sensor for Axisymmetric Waves in a Fluid Filled Pipe , 1994 .

[2]  H. V. Fuchs,et al.  Ten years of experience with leak detection by acoustic signal analysis , 1991 .

[3]  David Chapman,et al.  Mapping the Underworld – State-of-the-art review , 2007 .

[4]  Kihong Shin,et al.  Fundamentals of Signal Processing for Sound and Vibration Engineers , 2008 .

[5]  Michael J. Brennan,et al.  A model of the correlation function of leak noise in buried plastic pipes , 2004 .

[6]  Michael J. Brennan,et al.  Wavenumber prediction of waves in buried pipes for water leak detection , 2002 .

[7]  Michael J. Brennan,et al.  The design and instrumentation of an experimental rig to investigate acoustic methods for the detection and location of underground piping systems , 2008 .

[8]  Michael J. Brennan,et al.  Axisymmetric wave propagation in buried, fluid-filled pipes : Effects of wall discontinuities , 2005 .

[9]  A. N. Jette,et al.  Surface displacements accompanying the propagation of acoustic waves within an underground pipe , 1980 .

[10]  Michael J. Brennan,et al.  On the effects of reflections on time delay estimation for leak detection in buried plastic water pipes , 2009 .

[11]  Michael J. Brennan,et al.  Axisymmetric wave propagation in fluid-filled pipes: wavenumber measurements in in vacuo and buried pipes , 2004 .

[12]  J. Bendat,et al.  Random Data: Analysis and Measurement Procedures , 1987 .

[13]  Jennifer M. Muggleton,et al.  The use of acoustic methods to detect and locate underground piping systems , 2006 .

[14]  K. Graff.  Wave Motion in Elastic Solids , 1975 .