Stereology-based fabric analysis of microcracks in damaged granite

Takemura, Takato; Oda, Masanobu

doi:10.1016/j.tecto.2004.06.004

Cited by 31 publications

(12 citation statements)

References 42 publications

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“…1). For convenience, three orthogonal directions normal to these planes were taken as reference axes x i (i ¼ 1; 2; 3), and a plane normal to a reference axis x i is called the X i plane [13,16]. Under microscope, the minerals are almost randomly distributed in each thin section parallel to the X i plane (Fig.…”

Section: Test Materialsmentioning

confidence: 99%

“…Almost all of them are intragranular and grain-boundary (intergrain) cracks, and transgranular ones are very rare. Mean length of microcracks are about 1 mm for both intragrain and grain-boundary cracks [13,16]. The area crack density, r A;X i (mm/mm 2 ), defined as the total trace length divided by the observed area, changes considerably depending on the orientation of the observed X i plane; i.e., r A;X 1 ¼ 0:80, r A;X 2 ¼ 0:95, r A;X 3 ¼ 1:14 [13,16,17].…”

Section: Test Materialsmentioning

confidence: 99%

“…Mean length of microcracks are about 1 mm for both intragrain and grain-boundary cracks [13,16]. The area crack density, r A;X i (mm/mm 2 ), defined as the total trace length divided by the observed area, changes considerably depending on the orientation of the observed X i plane; i.e., r A;X 1 ¼ 0:80, r A;X 2 ¼ 0:95, r A;X 3 ¼ 1:14 [13,16,17]. About 70% of the crack density is occupied by intraquartz cracks, and the rest by intrafeldspar and grain-boundary cracks in all directions [13].…”

Section: Test Materialsmentioning

confidence: 99%

“…It is supposed that these differences are also due to the pre-existing microcrack fabrics, as Takemura and Oda [13,16] showed on microcracks in quartz and feldspar minerals. The intraquartz microcracks parallel to the X 1 plane are 2.7 times greater than the intrafeldspar ones.…”

Section: Surface Mineral Composition and Microcracksmentioning

confidence: 99%

See 3 more Smart Citations

Surface features of uniaxial tensile fractures and their relation to rock anisotropy in Inada granite

Fujii¹,

Takemura²,

Takahashi³

et al. 2007

International Journal of Rock Mechanics and Mining Sciences

Self Cite

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Section: Test Materialsmentioning

confidence: 99%

Section: Test Materialsmentioning

confidence: 99%

Section: Test Materialsmentioning

confidence: 99%

Section: Surface Mineral Composition and Microcracksmentioning

confidence: 99%

See 2 more Smart Citations

Surface features of uniaxial tensile fractures and their relation to rock anisotropy in Inada granite

Fujii¹,

Takemura²,

Takahashi³

et al. 2007

International Journal of Rock Mechanics and Mining Sciences

Self Cite

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“…N: microcrack number, L t : total length of microcrack, L m : mean length of microcrack, ρ: microcrack density, σ t : tensile strength, An (Anisotropy coefficient): Max-Min / Mean. 탄성 변형(inelastic deformation)을 반영하는 석영 입 자 내에서 대표적인 측정치를 구할 수 있는 이점이 있다 (Takemura and Oda, 2004). 한편 거창화강암의 수평면에 대한 박편의 확대사진 을 통한 미세균열의 유형을 크게 두 종류로 분류하였 다.…”

Section: 조사선법에 의한 방향각 별 미세균열의 길이(L) 및 수(N)는 모두 397개가 측정되었다(Table 1 및 unclassified

Characteristics of the Rock Cleavage in Jurassic Granite, Geochang

Park¹

2015

The Journal of the Petrological Society of Korea

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Jurassic granite from Geochang was analysed with respect to the characteristics of the rock cleavage. we have mainly discussed the structual anisotropy formed by microcracks. The phases of distribution of microcracks were well evidenced from the enlarged photomicrographs(× 6.7) of the thin section. The planes of principal set of microcracks are parallel to the rift plane and those of secondary set are parallel to the grain plane. These rift and grain microcracks are mutually near-perpendicular on the hardway planes. From the directional angle(θ) -total length(L t ), number(N) and density(ρ) chart, the curve patterns of the above microcrack parameters reflect the phases of distribution of microcracks. Microcrack parameters such as number, length and density show an order of rift > grain > hardway. These results indicate a relative magnitude of the rock cleavage. Meanwhile, brazilian tensile strengths were measured with respect to the six directions. The results revealed a strong correlation between mechanical property with the above microcrack parameters. These general results correspond to those of the previous study for Jurassic granites from Pocheon and Hapcheon. Image processing technique for the enlarged photomicrograph of the thin section was carried out. The grain 1(G1) microcrack arrays developed in quartz and feldspar grains show excellent distribution on the photomicrograph. In particular, the directional angle of each microcrack set can be ascertained easily by brief image processing for the above photomicrograph.

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Direct observations of damage during unconfined brittle failure of Carrara marble

2016

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To observe and quantify the production of microfracturing from initial yield to failure, we deformed Carrara marble samples in uniaxial compression at 20, 105, and 180°C and continuously observed a region of about 1 mm2 on an exposed face with a long‐working distance microscope. Using image processing and microscale strain‐mapping techniques, we measured local strains over a length scale of tens of micrometers. By treating the images with various filters, we identified linear damage features, as well as the magnitude of localized strain and the mode of deformation, i.e., shear versus normal deformation. In general, shear deformation is more prevalent after initial yielding, while tensile deformation dominates closer to peak stress. Independent measurements of both stress and microcrack density at different stages of each experiment provide a unique opportunity to explicitly compare the data with damage models. The model of Ashby and Sammis (1990) significantly underestimated the damage that the rock could sustain before peak stress, perhaps owing to the influence of weak grain boundaries on the damage production. In these samples, microcracks tended to form near boundaries before yield stress. During strain hardening, the damage parameters increased rapidly as longer microcracks grew along the boundaries and finally transected grains as loading neared peak stress. The microcrack density can be empirically related to the reduction of Young's modulus; stiffness ratios decay exponentially with increasing microcrack density for T ≤ 105°C.

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Stereology-based fabric analysis of microcracks in damaged granite

Cited by 31 publications

References 42 publications

Surface features of uniaxial tensile fractures and their relation to rock anisotropy in Inada granite

Surface features of uniaxial tensile fractures and their relation to rock anisotropy in Inada granite

Characteristics of the Rock Cleavage in Jurassic Granite, Geochang

Direct observations of damage during unconfined brittle failure of Carrara marble

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