Researchers at the Centre for Offshore Foundation Systems (COFS) this week published a new image-based method for measuring displacements and deformations that is seeing rapid adoption in research institutes worldwide.
Dr Sam Stanier and Professor David White, working with colleagues Justin Blaber at Georgia Tech and Professor Andy Take at Queens University Canada, have brought together technologies of digital image analysis and close range photogrammetry.
Their software program, known as GeoPIV-RG, is designed primarily for geotechnical experiments such as work performed in COFS’ geotechnical centrifuges, but has many wider applications. It turns a series of images into a detailed map of motion and distortion, with high precision and accuracy.
The performance of the new software was described in a paper published this week in the Canadian Geotechnical Journal. The software is provided as freeware to other researchers and has already been downloaded by more than 100 researchers at 56 research institutes from 6 continents through the website www.geopivrg.com.
“Our research uses new techniques of digital image correlation to detect the movement and distortion at thousands of point across an image, to a precision of around a thousandth of a pixel. We also apply close range photogrammetry. This is needed to correct the image for distortion from effects like fish-eye, or from refraction through a viewing window,” said Dr Stanier
Researchers at COFS are using the software to track the patterns of soil deformation beneath foundations and around anchors. These measurements provide quantitative evidence of the mechanisms that lead to settlement and failure.
With GeoPIV-RG, experimentalists can measure the detailed response of the surrounding soil. This is a valuable tool for benchmarking computer simulations of soil-structure behaviour. Researchers using previous versions of the software have unravelled the mechanisms that lead to failure of foundations, pipelines, anchors, retaining walls and many other geotechnical structures.
The original GeoPIV software, using earlier image analysis algorithms, was developed by Professors White and Take during their PhD study in Cambridge fifteen years ago. They popularised the use of image analysis for measuring deformations in geotechnics by applying it to a range of problems in the field and the laboratory. These ranged from detecting the subsidence of Victorian structures undermined during tunnelling beneath London, to measuring the propagation of landslides after rainfill. Their original publication is the most cited work in geotechnics this century, and this new contribution will provide a renewed impetus for new research avenues.
“With COFS hosting the National Geotechnical Centrifuge Facility, we need state-of-the-art sensing systems to gain maximum benefit from our experiments. Our image analysis technology has been widely used across the research community for the past 15 years. The new approach published this week provides an order of magnitude improvement in precision, so we can now see geotechnical behaviour that was previously invisible”, said Professor White, who holds the Shell EMI Chair in Offshore Engineering at UWA.
EMI Director Mark Stickells said the success of the project was well-deserved, "In EMI's support of COFS research, we congratulate the team on their international success on this project."
Image: Dr Sam Stanier assembling imaging appratus in the UWA drum centrifuge.
EMI Communications Coordinator Nicola Holman +61 439 906 200