Advances in Computed Tomography for Geomaterials: GeoX 2010

Quantitative Description of Grain Contacts in a Locked Sand

J. Fonseca¹ — C. O’Sullivan² — M. R. Coop³

Imperial CollegeGeotechnics SectionLondon SW7 [e-mail]

ABSTRACT. Quantifying the fabric of intact soil is of great importance in both geomechanics and geology. A unique and interesting example of fabric can be found in “locked sands”. These geologically old sands are characterized by significant grain interlocking and a low cement content. They can be sampled with minimal fabric disturbance. This study analyzes images acquired by x-ray microtomography of resin impregnated samples of a natural sand, Reigate Silver Sand part of the Folkestone Bed formation from southeast England. 2D and 3D image analyses were carried out to identify the grain-grain contacts and quantify individual contact areas. In contrast to earlier studies that have focused on the coordination number, this work demonstrates that for non-punctual contacts a measure of fabric that considers the contact area may be more appropriate.

 

KEYWORDS: granular material, fabric, contacts, image analysis, locked sands

1. Introduction

This paper considers fabric characterization of a type of natural sand formation referred to as a “locked sand”. The term “locked sand” was introduced by Dusseault and Morgestern (1979) to describe sands that, due to particular deposition conditions, have very low porosity values and a fabric comprising of inter-locked grains. ...