Digital image correlation for surface deformation measurement: historical developments, recent advances and future goals

This paper describes and benchmarks a new implementation of image-based deformation measurement for geotechnical applications. The updated approach combines a range of advances in image analysis al...

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Improved image-based deformation measurement for geotechnical applications

https://api.research-repository.uwa.edu.au/ws/files/119880944/Full_text.pdf

Large deformation finite element analyses in geotechnical engineering

Digital image correlation (DIC) is an image-processing technique that calculates fields of incremental displacement by comparing two digital images and locating numerous small regions in both image...

Thirty-Sixth Canadian Geotechnical Colloquium: Advances in visualization of geotechnical processes through digital image correlation1

Constitution d'une base de donnees, a partir d'essais triaxiaux non draines et d'essais de cisaillement simple direct sur argile de Drammen, avec combinaison de contraintes de cisaillement statique et dynamiques

Cyclic soil data for design of gravity structures

Assessment of the risk of punch-through failure of spudcan foundations on sand overlying clay requires prediction of the full penetration resistance profile, from touchdown and through punch-throug...

/pdf/predicting-the-resistance-profile-of-a-spudcan-penetrating-3lh7rlauta.pdf

Predicting the resistance profile of a spudcan penetrating sand overlying clay

Accurately predicting peak penetration resistance qpeak during spudcan installation into sand overlying clay is crucial to an offshore mobile jack-up industry still suffering regular punch-through failures. This paper describes a series of spudcan penetration tests performed on medium-loose sand overlying clay and compares the response to existing centrifuge data from tests performed on dense sand overlying clay. Together these data demonstrate that punch-through is a potential problem for both dense and loose sand overlying clay soil stratigraphies. Using this experimental database, a failure-stress-dependent model has been modified to account for the embedment depth, and the depth of occurrence of qpeak is shown to be a function of the sand thickness Hs. The model then was recalibrated, taking these findings into account, for a larger range of material properties and ratios of sand thickness to spudcan diameter (Hs=D). Finally, the performance of the modified and recalibrated model is verified by comparing its predictions with those calculated using current guidelines. The comparisons show that the modified model yields more accurate predictions of qpeak over the range of Hs=D ratios of practical interest, which when used in practice will potentially mitigate the risk of unexpected punch-through on sand overlying clay stratigraphies. © 2013 American Society of Civil Engineers.

/pdf/predicting-peak-resistance-of-spudcan-penetrating-sand-44fkp5jmcw.pdf

Predicting Peak Resistance of Spudcan Penetrating Sand Overlying Clay

This paper describes a new apparatus and techniques for performing deformation measurements using particle image velocimetry in the centrifuge environment. The new system includes camera, lighting, and control equipment that facilitates image capture at least 30 times faster than that in legacy systems. Methods for optimizing the addition of artificial seeding on the exposed plane of a geotechnical model are also set out. These techniques ensure that the precision of the deformation calculations is optimized even in models with multiple layers of different soils, fully harnessing the method's capabilities. An example application of a flat footing penetrating sand overlying clay is used to illustrate the performance of the equipment and the artificial seeding optimization technique. Deformation fields at the point of peak resistance during punch-through are presented in the form of vector fields, normalized displacement contours, and shear strain contours. It is shown that the advances in equipment and artificial seeding allow both macroscopic and grain-scale deformation features to be identified. These analyses highlight not only the benefits of the new technology, but also the need for carefully optimized experimental procedures to maximize the measurement precision.

Improved Image-Based Deformation Measurement in the Centrifuge Environment

A complete analytical method to describe the full load-penetration resistance profile of a mobile jack-up spudcan footing penetrating a sand over clay stratigraphy is described. It is based on both large deformation finite-element analyses and geotechnical centrifuge experiments. The coupled Eulerian–Lagrangian (CEL) approach is used to accommodate the large deformations of a spudcan footing penetrating sand overlying clay. Modified Mohr–Coulomb and Tresca models describe the sand and clay behaviour, with modifications accounting for the effects of strain softening on the response of the soil. The CEL results are shown to match centrifuge tests well, allowing the numerical study to be extended parametrically, and with confidence, to cover the range of layer geometries, sand relative densities and footing shapes that are of practical interest to offshore jack-ups. The results are used to (a) assess the performance of an existing model to predict the peak resistance in the sand layer (extending its range of...

/pdf/assessing-the-punch-through-hazard-of-a-spudcan-on-sand-2axv4osfi9.pdf

Sam Stanier

Papers

Improved image-based deformation measurement for geotechnical applications

Predicting the resistance profile of a spudcan penetrating sand overlying clay

Predicting Peak Resistance of Spudcan Penetrating Sand Overlying Clay

Improved Image-Based Deformation Measurement in the Centrifuge Environment

Assessing the punch-through hazard of a spudcan on sand overlying clay