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On the detection of objects buried at a shallow depth using seismic wave reflections
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10.1121/1.3552878
/content/asa/journal/jasa/129/3/10.1121/1.3552878
http://aip.metastore.ingenta.com/content/asa/journal/jasa/129/3/10.1121/1.3552878

Figures

Image of FIG. 1.
FIG. 1.

Diagram of the experimental setup used for the measurements. The origin of the coordinate system is defined at the left hand side of the measurement line with the vertical coordinate increasing with depth from the surface.

Image of FIG. 2.
FIG. 2.

Schematic of the procedure for synthesis of simulated geophone data.

Image of FIG. 3.
FIG. 3.

Image produced using the imaging algorithm with simulated geophone data. The target is defined in the simulation by the white bold line. The circles at the surface indicate geophone locations and the square indicates the excitation location. These are chosen to coincide with their locations in the experimental measurements presented in Sec. VI.

Image of FIG. 4.
FIG. 4.

Same as Fig. 3, but without the inclusion of the surface wave.

Image of FIG. 5.
FIG. 5.

(a) Photograph and (b) drawing of the platform used to couple the shaker to the ground.

Image of FIG. 6.
FIG. 6.

Photograph of the experimental setup used for the measurements to determine the image through the ground. The source is in the same location as for the experimental results given in Sec. VI. Each sensor location has both vertical and horizontally orientated geophones. (Note that the sensor location 6 is outside of the image and thus not shown, and that this photograph was taken prior to the insertion of the reference geophone.)

Image of FIG. 7.
FIG. 7.

(a) Plot of the unwrapped phase of the frequency response function between two surface sensors. The dashed straight line shows an approximately linear region from which a wavespeed has been estimated. (b) Plot of the GCC (PHAT) function between the same surface sensors. The GCC envelope, obtained via the Hilbert transform, is shown in bold. The biased cross-correlation estimate has been used.

Image of FIG. 8.
FIG. 8.

(a) Plot of the unwrapped phase of the frequency response function between the shaker and pipe accelerometers. The dashed straight line shows an approximately linear region from which the body wavespeed has been estimated. (b) Plot of the GCC (PHAT) function between the shaker and pipe accelerometers. The GCC envelope, obtained via the Hilbert transform, is shown in bold. The biased cross-correlation estimate has been used.

Image of FIG. 9.
FIG. 9.

Time-domain plots of the measured geophone signals. The bottom six plots are the signals from the measurement geophones and the top plot is the signal from the reference geophone. The source was located between the fourth and fifth geophones. This labeling corresponds to that shown in Fig. 5. Each signal is italicized to its peak value for clarity.

Image of FIG. 10.
FIG. 10.

Plots of the GCC (PHAT) functions between the measurement geophones and the reference geophone. The GCC envelopes, obtained via the Hilbert transform, are shown in bold. The biased cross-correlation estimate has been used.

Image of FIG. 11.
FIG. 11.

Image produced from the cross-correlation functions of Fig. 9 using the imaging algorithm. The expected position of the target is shown as white bold line. The circles at the surface indicate geophone locations and the square the excitation location.

Tables

Generic image for table
TABLE I.

Parameters used in the imaging algorithm simulation. The wavespeed values have been taken from the experimental results of Sec. VI.

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/content/asa/journal/jasa/129/3/10.1121/1.3552878
2011-03-09
2014-04-23
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: On the detection of objects buried at a shallow depth using seismic wave reflections
http://aip.metastore.ingenta.com/content/asa/journal/jasa/129/3/10.1121/1.3552878
10.1121/1.3552878
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