City Research Online

Abstract

Image-based analysis is a growing field in geotechnical engineering and has a wide range of applications from measuring particle size distribution to observing the three dimensional internal deformation of granular materials. In centrifuge modelling, pre-failure deformation can be captured from the visible vertical plane of the models. This paper describes a new set-up for measuring a two dimensional displacement field using particle image velocimetry (PIV). The system makes use of the texture (intensity of pixel) of images to determine the accurate pattern of pre-failure ground movements. A complementary metal oxide semiconductor (CMOS) sensor is employed rather than a charged couple device (CCD) sensor used in previous studies. Three examples are presented: (1) synthetic experiment using a sliding bed equipped with LVDT behind the window of a strong box to make and measure controlled displacements; (2) strip footing test on glass ballotini under vertical loading; (3) ground movement generated during a shaft construction in clay. These examples provide a range of tests with artificial texture and demonstrate the most important parameters governing the experimental set-up and image analysis. The possibility of using PIV for grain scale investigations is dis-cussed. The study highlights the benefits of new technology and provides guidelines to minimise artefacts in image processing.

Publication Type:	Conference or Workshop Item (Paper)
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Departments:	School of Science & Technology > Engineering

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