Trends in the Evolution of Particle Morphology with Size in Colluvial Deposits Overlying Channel Iron Deposits

Sandra Linero, Stephen Fityus, John Simmons, Arcesio Lizcano, Jessica Cassidy
Monday, July 3, 2017
First presented: 
Powders and Grains
Published paper

Size limitations of testing equipment often imply that samples of coarse granular materials must be scalped or scaled, to reduce the size of the constitutive particles, before they can be tested either by triaxial or direct shear in the laboratory. The objective of the investigation is to evaluate the particle shapes in a natural sample of colluvial sediments, to identify potential correlation(s) between shape and size, that could impact shear strength of scaled samples. The material investigated is derived from eroded ancient sedimentary rocks from the Pilbara region of Australia. The fragments have a particle shape ranging from slabs to sub-equant blocks.  The observation indicates that there is an increase in the tendency for slab-shapes in larger particles. Therefore, scaling inevitably alters the characteristic shapes of the material particles as it implies substituting larger (slabs) particles by smaller (sub-equant) particles.  Changes in particle shape distribution may induce changes in material fabric and shear strength and therefore may need to be considered when scaling samples.

Feature Author

Dr. Arcesio Lizcano

Arcesio is a civil engineer with more than 30 years of experience in geotechnical engineering including research and teaching in soil mechanics. He has extensive experience in engineering design and construction, including construction oversight of foundations, excavations, road embankments, retaining structures, and stockpiles and waste dumps.

Arcesio specializes in understanding the behaviour of sand and clays and applying that understanding to practical problems. He has contributed to civil and mining projects in Asia, Europe, Africa, North and South America. He has published over seventy papers in journals and conferences.

Soil Mechanics Specialist
PhD, Geotechnical Engineering
SRK Vancouver
SRK North America