JOURNAL OF ROCK MECHANICS

JOURNAL OF ROCK MECHANICS

Experimental Investigation of the Effect of Grain Size on the Mechanical Parameters and Mode I Fracture Toughness of Rock-Like Materials

Document Type : Original Article

Authors
Ali Doostan 1
Seyed Mosleh Eftekhari 2
Morteza Ahmadi 1
1 Faculty of Mining and Materials, Tarbiat Modares University, Tehran, Iran
2 Faculty of Engineering, Tarbiat Modares University, Tehran, Iran.
10.22034/IRSRM.2024.508585.1894
Abstract
The mechanical properties of rocks are significantly influenced by their microstructure, texture, and petrographic characteristics. One of the most critical microstructural parameters is grain size, whose effect on rock strength has yielded inconsistent results in previous studies due to the influence of other microstructural factors. This study investigates the effect of grain size on the mechanical parameters and mode I fracture toughness of artificial rock samples while keeping other microstructural factors constant. To achieve this, three groups of artificial rock samples with identical composition but different grain sizes were prepared and subjected to laboratory tests, including uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), and mode I fracture toughness. The experimental results indicate that grain size plays a crucial role in determining the mechanical behavior of rocks. An increase in grain size leads to a significant decrease in UCS, BTS, and elastic modulus, while mode I fracture toughness exhibits a strong negative correlation with grain size. The correlation coefficients between grain size and UCS (R=-0.95), BTS (R=-0.93), elastic modulus (R=-0.98), and mode I fracture toughness (R=-0.94) confirm the strong influence of grain size on these properties. Additionally, considering grain size in fracture toughness prediction models improves their accuracy. These findings highlight the importance of accounting for grain size in rock mechanical analyses and predictive fracture behavior models.
Keywords
Grain size
Uniaxial compressive strength
Brazilian tensile strength
Fracture toughness mode I
Subjects
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JOURNAL OF ROCK MECHANICS
Volume 8, Issue 2
Summer 2024
Pages 21-34