Effect of Water on the Deformation and Failure of Rock in Uniaxial Tension

Hashiba, Kimihiro; Fukui, Katsunori

doi:10.1007/s00603-014-0674-x

Cited by 120 publications

(50 citation statements)

References 21 publications

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“…To validate the test set-up, some preliminary tests were carried out on ostensibly homogeneous samples of Blackhill Quarry sandstone (lacking visible fabric), using a similar set-up to that of Okubo and Fukui (1996) and Hashiba and Fukui (2014). Four strain gauges (10 mm in length) were attached to the middle of the specimens.…”

Section: Testing Apparatus Set-up and Verificationmentioning

confidence: 99%

Tensile Strength of Geological Discontinuities Including Incipient Bedding, Rock Joints and Mineral Veins

2016

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Geological discontinuities have a controlling influence for many rock-engineering projects in terms of strength, deformability and permeability, but their characterisation is often very difficult. Whilst discontinuities are often modelled as lacking any strength, in many rock masses visible rock discontinuities are only incipient and have tensile strength that may approach and can even exceed that of the parent rock. This fact is of high importance for realistic rock mass characterisation but is generally ignored. It is argued that current ISRM and other standards for rock mass characterisation, as well as rock mass classification schemes such as RMR and Q, do not allow adequately for the incipient nature of many rock fractures or their geological variability and need to be revised, at least conceptually. This paper addresses the issue of the tensile strength of incipient discontinuities in rock and presents results from a laboratory test programme to quantify this parameter. Rock samples containing visible, natural incipient discontinuities including joints, bedding, and mineral veins have been tested in direct tension. It has been confirmed that such discontinuities can have high tensile strength, approaching that of the parent rock. Others are, of course, far weaker. The tested geological discontinuities all exhibited brittle failure at axial strain less than 0.5 % under direct tension conditions. Three factors contributing to the tensile strength of incipient rock discontinuities have been investigated and characterised. A distinction is made between sections of discontinuity that are only partially developed, sections of discontinuity that have been locally weathered leaving localised residual rock bridges and sections that have been 'healed' through secondary cementation. Tests on bedding surfaces within sandstone showed that tensile strength of adjacent incipient bedding can vary considerably. In this particular series of tests, values of tensile strength for bedding planes ranged from 32 to 88 % of the parent rock strength (intact without visible discontinuities), and this variability could be attributed to geological factors. Tests on incipient mineral veins also showed considerable scatter, the strength depending upon the geological nature of vein development as well as the presence of rock bridges. As might be anticipated, tensile strength of incipient rock joints decreases with degree of weathering as expressed in colour changes adjacent to rock bridges. Tensile strengths of rock bridges (lacking marked discolouration) were found to be similar to that of the parent rock. It is concluded that the degree of incipiency of rock discontinuities needs to be differentiated in the process of rock mass classification and engineering design and that this can best be done with reference to the tensile strength relative to that of the parent rock. It is argued that the science of rock mass characterisation may be advanced through better appreciation of geological history at a site thereby improving the ...

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Section: Testing Apparatus Set-up and Verificationmentioning

confidence: 99%

Tensile Strength of Geological Discontinuities Including Incipient Bedding, Rock Joints and Mineral Veins

2016

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“…De et al (2005) conducted axial compression experiments with Carrara marble with and without water, and these authors found water-soaked specimens to be slightly weaker than dry specimens. Hashiba and Fukui (2014) researched the tensile strength of granite under wet conditions and its weakening mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Study of fracture toughness and weakening mechanisms in gypsum interlayers in corrosive environments

Meng

Fang

et al. 2015

Journal of Natural Gas Science and Engineering

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“…A considerable number of studies have been carried out to investigate the influence of water content on mechanical properties and failure characteristics of coal and rock mass [7][8][9][10][11][12]. According to former studies, the uniaxial compressive strength, elastic modulus, and tensile strength of the rock all decline as moisture content increases.…”

Section: Introductionmentioning

confidence: 99%

Effects of Water-Soaking Height on the Deformation and Failure of Coal in Uniaxial Compression

et al. 2019

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The stability of water-preventing coal pillar plays an important role in preventing gob water inrush. The gob side of the water-preventing coal pillar is soaked in a certain height of mine water. Different soaking heights may affect the stability of coal pillars. Few studies have been conducted on the properties of coals with different water-soaking heights. We carried out uniaxial compressive tests on coal specimens with different water-soaking heights to gain a better understanding of different water-soaking-height-induced weakening characteristics of coal. Results show that: (1) The water content of coal specimens increases with the soaking height. Water significantly weakens the strength of coal specimens. However, the extent of strength weakening of the coal specimen does not increase with the increase of the soaked height. The strength of the fully soaked coal specimen is lowest among all groups of coal specimens. The strength of the three groups of partially soaked coal specimens is between the fully soaked coal specimens and the coal specimens without being soaked in the water. In the three groups of partially soaked coal specimens, the strength of the coal specimens increases with the increase of the soaking height. (2) The acoustic emission activities of complete water soaking and nonsoaking coal specimens are relatively concentrated, occurring mainly in unstable fracture expansion stage and post-peak destruction stage, and acoustic emission exhibits main-shock mode. Partially soaking coal specimens, especially the 25% water-soaking height and 50% water-soaking height coal specimens, produces obvious acoustic emission activities during the fracture expansion stabilization phase, and then generates more acoustic emission activities during the unstable expansion stage and the post-peak stage. The acoustic emission presents foreshock-main shock mode. (3) The softening effect of the water soaking on the coal specimens is obvious. It was further found that the deformation of coal specimens with partial water soaking is not synchronized in different layers, the nonuniform deformations of partially soaked coal specimens aggravate its damage.

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Effect of Water on the Deformation and Failure of Rock in Uniaxial Tension

Cited by 120 publications

References 21 publications

Tensile Strength of Geological Discontinuities Including Incipient Bedding, Rock Joints and Mineral Veins

Tensile Strength of Geological Discontinuities Including Incipient Bedding, Rock Joints and Mineral Veins

Study of fracture toughness and weakening mechanisms in gypsum interlayers in corrosive environments

Effects of Water-Soaking Height on the Deformation and Failure of Coal in Uniaxial Compression

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