Analysis of size effects on the geomechanical parameters of intact granite samples under unconfined conditions

• Published in: Acta geotechnica Vol. 12; no. 6; pp. 1229 - 1242
• Main Authors: Quiñones, J., Arzúa, J., Alejano, L. R., García-Bastante, F., Mas Ivars, D., Walton, G.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2017; Springer Nature B.V
• Subjects: Complex Fluids and Microfluidics; Compressive strength; Crack initiation; Engineering; Environmental conditions; Foundations; Geoengineering; Geology; Geomechanics; Geotechnical Engineering & Applied Earth Sciences; Granite; Hydraulics; Mechanical properties; Modulus of elasticity; Poisson's ratio; Research Paper; Sample size; Size; Size effects; Soft and Granular Matter; Soil Science & Conservation; Solid Mechanics; Stone; Unconditioned stimulus; Compressive strength; Size effect; Granite; Intact rock
• ISSN: 1861-1125; 1861-1133
• DOI: 10.1007/s11440-017-0531-7

A total of 28 uniaxial compressive strength tests were performed on cylindrical Blanco Mera granite samples with diameters ranging between 14 and 100 mm, with results indicating that this granite undergoes a significant reverse size effect: the UCS increases as sample diameter increases up to 54 mm, but thereafter decreases. It was also found that the results tend to be more scattered for smaller sample diameters. We also found an apparent correlation between Young’s modulus and sample diameter. It was not possible to draw any clear conclusions regarding the variability in Poisson’s ratio with sample size. With respect to crack initiation and crack damage stresses, the behaviour of the tested samples also indicates a reverse effect. This research would suggest that the traditionally assumed decrease in strength as sample size increases does not hold for granite samples with diameters below 54 mm.