p-Wave reflection imaging of submerged soil models using ultrasound / Joseph Coe in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 10 (Octobre 2010)  

p-Wave reflection imaging of submerged soil models using ultrasound [texte imprimé] / Joseph Coe, Auteur ; Scott J. Brandenberg, Auteur . - 2010 . - pp. 1358-1367.
Géotechnique
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 10 (Octobre 2010) . - pp. 1358-1367

Mots-clés :	Soils Ultrasonic methods Transfer functions Transducers Imaging techniques Signal processing Submerging Reflection Compression waves
Index. décimale :	624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels
Résumé :	An ultrasonic p-wave reflection imaging system is used to noninvasively image submerged soil models with embedded anomalies and complex geometric layer contacts. The ultrasonic transducers emit compressive waves into water that subsequently transmit into the underlying soil, and measurements of the reflections are used to construct the images. The properties of the transducers and data acquisition hardware and software are explained. Fast signal stacking is used to improve signal-to-noise ratio and provide clearer images. Transducer directivity is explained as a wave passage effect, and transfer functions are derived for square and circular transducers to quantify directivity. The transfer functions agree reasonably with measured amplitude data. The cause of errors in the imaged position of dipping reflectors is explained, and a Kirchhoff migration algorithm is implemented to correct these errors. A soil model consisting of embedded high- and low-impedance anomalies, dipping soil layer contacts, and an undulating concrete base layer was imaged using 500- and 100-kHz transducers. The geometric features of the model are clearly visible in the images recorded with the 500-kHz transducers and less clear with the 100-kHz transducers. The lateral spatial resolution of the migrated images is shown to be much larger than one wavelength.
DEWEY :	624.1
ISSN :	1090-0241
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