Validation of a BOTDR-based system for the detection of smuggling tunnels

Cross-border smuggling tunnels enable unmonitored movement of people, drugs and weapons and pose a very serious threat to homeland security. Recently, Klar and Linker (2009) [SPIE paper No. 731603] presented an analytical study of the feasibility of a Brillouin Optical Time Domain Reflectometry (BOTDR) based system for the detection of small sized smuggling tunnels. The current study extends this work by validating the analytical models against real strain measurements in soil obtained from small scale experiments in a geotechnical centrifuge. The soil strains were obtained using an image analysis method that tracked the displacement of discrete patches of soil through a sequence of digital images of the soil around the tunnel during the centrifuge test. The results of the present study are in agreement with those of a previous study which was based on synthetic signals generated using empirical and analytical models from the literature.

[1]  T. Horiguchi,et al.  A technique to measure distributed strain in optical fibers , 1990, IEEE Photonics Technology Letters.

[2]  Pj Bennett,et al.  Distributed Optical Fiber Strain Sensing in a Secant Piled Wall , 2007 .

[3]  Assaf Klar,et al.  Feasibility study of the automated detection and localization of underground tunnel excavation using Brillouin optical time domain reflectometer , 2009, Defense + Commercial Sensing.

[4]  D. Kell,et al.  Variable selection in wavelet regression models , 1998 .

[5]  Pj Bennett,et al.  The use of fibre optic sensors to monitor pipeline response to tunnelling , 2006 .

[6]  H. Ohno,et al.  Industrial Applications of the BOTDR Optical Fiber Strain Sensor , 2001 .

[7]  F Ehrentreich.  Wavelet transform applications in analytical chemistry , 2002, Analytical and bioanalytical chemistry.

[8]  Robert J. Mair,et al.  SUBSURFACE SETTLEMENT PROFILES ABOVE TUNNELS IN CLAYS , 1993 .

[9]  K. Jetter,et al.  Quantitative analysis of near infrared spectra by wavelet coefficient regression using a genetic algorithm , 1999 .

[10]  A. R. Selby,et al.  Soil Movements Induced by Tunnelling and Their Effects on Pipelines and Structures , 1986 .

[11]  X. Bao,et al.  Simultaneous distributed strain and temperature measurement. , 1999, Applied optics.

[12]  Alexander Kai-man Leung,et al.  Application of wavelet transform in infrared spectrometry: spectral compression and library search , 1998 .

[13]  Simon Haykin,et al.  Neural networks , 1994 .

[14]  W. A. Take,et al.  Soil deformation measurement using particle image velocimetry (PIV) and photogrammetry , 2003 .

[15]  Desire L. Massart,et al.  Noise suppression and signal compression using the wavelet packet transform , 1997 .

[16]  X. Bao,et al.  Distributed Brillouin fiber sensor for detecting pipeline buckling in an energy pipe under internal pressure. , 2006, Applied optics.

[17]  J. R. Booker,et al.  Surface settlements due to deformation of a tunnel in an elastic half plane , 1996 .

[18]  Pj Bennett,et al.  Distributed strain measurement for pile foundations , 2006 .

[19]  Anthony W. Brown,et al.  Strain measurement in a concrete beam by use of the Brillouin-scattering-based distributed fiber sensor with single-mode fibers embedded in glass fiber reinforced polymer rods and bonded to steel reinforcing bars. , 2002, Applied optics.

[20]  S. Wold,et al.  PLS regression on wavelet compressed NIR spectra , 1998 .