Eur. Phys. J. B 7, 179-182 (1999)
https://doi.org/10.1007/s100510050602

Roughness of sandstone fracture surfaces: Profilometry and shadow length investigations

¹ Laboratoire Fluides, Automatique et Systèmes Thermiques (UMR CNRS 7608) , Bâtiment 502, Campus universitaire, 91405 Orsay Cedex, France
² Grupo de Medios Porosos, Facultad de Ingenieria, Buenos-Aires, Argentina
³ Institut de Mécanique des Fluides de Toulouse, avenue du Président Camille Soula, 31400 Toulouse, France
⁴ Laboratoire "Surface du Verre et Interface" (UMR CNRS/St. Gobain) , 39 quai L. Lefranc, B.P. 135, 93303 Aubervilliers Cedex, France

Received: 29 June 1998
Revised: 25 September 1998
Accepted: 5 October 1998
Published online: 15 January 1999

Abstract

The geometrical properties of fractured sandstone surfaces were studied by measuring the length distribution of the shadows appearing under grazing illumination. Three distinct domains of variation were found: at short length scales a cut-off of self-affinity is observed due to the inter-granular rupture of sandstones, at long length scales, the number of shadows falls off very rapidly because of the non-zero illumination angle and of the finite roughness amplitude. Finally, in the intermediate domain, the shadow length distribution displays a power law decrease with an exponent related to the roughness exponent measured by mechanical profilometry. Moreover, this method is found to be more sensitive to deviations from self-affinity than usual methods.