ISSN: 1945-7545
CODEN: GTJODJ
Published Online: 15 June 2010
Page Count: 8

Spatial Deformation Measurement Using Transparent Soil

Iskander, Magued
Associate Professor, Polytechnic Institute of New York Univ., Brooklyn, NY

Liu, Jinyuan
Assistant Professor, Ryerson Univ., Toronto, ON

(Received 19 September 2009; accepted 1 April 2010)

Abstract

This paper addresses the need for nonintrusively measuring spatial deformation pattern inside soils. In this study, transparent soil surrogates are used in model tests instead of natural soils. Transparent soil with macrogeotechnical properties similar to those of natural soils was made of either transparent amorphous silica gels or powders and a pore fluid with a matching refractive index. An optical system consisting of a laser light, a line-generator lens, a charge-coupled device (CCD) camera, a frame grabber, and a computer was developed to optically slice a transparent soil model. A distinctive speckle pattern is generated by the interaction of the laser light and transparent soil. The laser speckle images before and after deformation were used to nonintrusively measure the relative displacement field using digital image cross-correlation. Spatial displacement fields under a model footing were obtained by combining several cross-sections in MATLAB^®. Test results showed that the developed optical system and transparent soil are suitable for studying soil-structural interaction problems.

Keywords:
transparent soil, optical test, image processing, digital image cross-correlation, PIV, particle image velocimetry, displacement field, non-intrusive measurement, three-dimensional analysis, model tests

Paper ID: GTJ102745
DOI: 10.1520/GTJ102745
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