In-Situ Observation of Cracks in Frozen Soil using Synchrotron Tomography
Version of Record online: 3 MAY 2012
Copyright © 2012 John Wiley & Sons, Ltd.
Permafrost and Periglacial Processes
Volume 23, Issue 2, pages 170–176, April 2012
How to Cite
Bhreasail, Á. N., Lee, P. D., O'Sullivan, C., Fenton, C. H., Hamilton, R., Rockett, P. and Connolley, T. (2012), In-Situ Observation of Cracks in Frozen Soil using Synchrotron Tomography. Permafrost Periglac. Process., 23: 170–176. doi: 10.1002/ppp.1737
- Issue online: 6 JUN 2012
- Version of Record online: 3 MAY 2012
- Manuscript Revised: 16 FEB 2012
- Manuscript Accepted: 16 FEB 2012
- Manuscript Received: 22 JUL 2011
- ice lenses;
- Micro computed tomography;
- frozen soil
Phase-contrast synchrotron micro-computed tomography (μCT) is well suited to studying the microstructure of frozen soil. To take advantage of the high-resolution three-dimensional images that can be generated using μCT, a specialised in-situ rig was designed and commissioned. This miniature temperature-controlled oedometer is capable of controlling soil sample thermal gradients and applying uniaxial deformation while measuring stress. This system was used to apply repeated freeze-thaw cycles to water-saturated samples of Leighton Buzzard sand, Reigate sand and spherical glass ballotini (an idealised soil). High-resolution images were obtained using a monochromatic, parallel beam of x-rays generated on Beamline I12 of the Diamond synchrotron. Cracking in the ice was directly measured utilising the phase-contrast fringes generated by ice-air interfaces. Examination of these images revealed two modes of crack formation in the ice phase of frozen soil: micro-cracks between soil particles, and longer, well-developed cracks that follow along ice-soil particle boundaries and span across the ice between particles. Both crack types were orientated parallel to the freezing front (normal to the heat flow), affecting both the frozen soils' mechanical behaviour, and we hypothesise that these cracks are potential initiation sites for ice lens development. Copyright © 2012 John Wiley & Sons, Ltd.