Estimating the potential for spalling around a deep nuclear waste repository in crystalline rock

Martin, C. Derek; Christiansson, R.

doi:10.1016/j.ijrmms.2008.03.001

Cited by 257 publications

(87 citation statements)

References 13 publications

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“…These stress thresholds are essential and useful parameters for engineering projects. For example, the crack initiation stress can be used to estimate the lower limit value of spalling rock mass strength [3,4]. Some brittleness indices have strong correlations with the crack damage stress and peak stress [5].…”

Section: Introductionmentioning

confidence: 99%

Study on the Progressive Failure Characteristics of Coal in Uniaxial and Triaxial Compression Conditions Using 3D-Digital Image Correlation

Tang

Okubo

et al. 2018

Energies

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Abstract:To investigate the progressive failure process of coal, a series of uniaxial and triaxial compression tests were conducted and a novel 3D digital image correlation instrument with six cameras combined with a special transparent pressure cell was used for the strain measurement. The stress thresholds of coal were obtained in uniaxial and triaxial compression. The energy evolution during the compression was discussed, coupled with the crack volumetric strain. The field strain of the whole specimen surface and crack propagation at different stress levels were described to study the progressive failure mechanism of coal. The average stress level of crack initiation and crack damage of coal in uniaxial compression are 43.75% and 63.03%, while that in the triaxial compression are 74.53% and 89.84%, respectively. The dissipation energy evolution corresponds to the crack volumetric strain, while the elastic energy release leads to flake ejection and coal failure. The crack evolution and localization of coal indicated the progressive failure process that the coal sample undergoes in tension failure in uniaxial compression and in tension-shear failure in triaxial compression. The findings of this study can serve as a reference to understand the failure process of coal and improve the stability and safety of mining engineering.

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Section: Introductionmentioning

confidence: 99%

Study on the Progressive Failure Characteristics of Coal in Uniaxial and Triaxial Compression Conditions Using 3D-Digital Image Correlation

Tang

Okubo

et al. 2018

Energies

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“…Researchers have suggested that the crack initiation observed in laboratory compression tests provides a good estimate of the operational spalling strength observed in hard brittle rocks around underground openings (Diederichs, 2007;Andersson et al, 2009;Martin and Christiansson, 2009;Rojat et al, 2009). Damjanac and Fairhurst (2010) suggested that crack initiation may also be used as a lower bound estimate for the long-term strength threshold of crystalline rocks.…”

Section: Introductionmentioning

confidence: 99%

Detection of Cracking Levels in Brittle Rocks by Parametric Analysis of the Acoustic Emission Signals

2015

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Determination of the cracking levels during the crack propagation is one of the key challenges in the field of fracture mechanics of rocks. Acoustic emission (AE) is a technique that has been used to detect cracks as they occur across the specimen. Parametric analysis of AE signals and correlating these parameters (e.g. hits and energy) to stress-strain plots of rocks let us detect cracking levels, properly. The number of AE hits is related to the number of cracks, and the AE energy is related to magnitude of the cracking event. For a full understanding of the fracture process in brittle rocks, prismatic specimens of granite containing pre-existing flaws have been tested in uniaxial compression tests, and their cracking process was monitored with both AE and high-speed video imaging. In this paper the characteristics of the AE parameters and the evolution of cracking sequences are analyzed for every cracking level. Based on micro-and macro-crack damage, a classification of cracking levels is introduced. This classification contains eight stages 1) crack closure, 2) linear elastic deformation, 3) micro-crack initiation (white patch initiation), 4) micro-crack growth (stable crack growth), 5) micro-crack coalescence (macro-crack initiation), 6) macro-crack growth (unstable crack growth), 7) macro-crack coalescence and 8) failure.

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“…Martin and Christiansson (2009) suggest that the magnitude of in-situ spalling strength for glacially eroded massive Scandinavian Crystalline rocks lies between 55% and 65% of the intact rock strength while the laboratory tested Crack Initiation (CI) strength may be between 40 and 50% of the intact rock strength (σci). Comparison of the CI values measured in laboratory uniaxial tests and the rock mass spalling strength by Martin et al (1999) suggests that the crack initiation provides the lower bound limit for the rock spalling strength.…”

Section: Maximum Tangential Stress and Rock Spalling Strengthmentioning

confidence: 99%

“…These four methods represent either empirical or semi-analytical approaches and are classified by Panthi (2017) as; 1) Norwegian Rule of Thumb (Selmer-Olsen, 1965), 2) Stress Problem Classification -part of Q-system (Barton et al 1974), 3), Uniaxial Compressive Strength and Tensile Strength Approach (Diederichs, 2007) and 4), Maximum Tangential Stress and Crack Initiation Strength Approach (Martin and Christiansson, 2009). Finally, discussions are also made on the limitations and extent of their applicability and improvements are suggested to improve the applicability of the fourth method, which can be used through engineering decision-making process.…”

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confidence: 99%

Methods Applied in the Prediction of Brittle Failure in Tunnels and Underground Caverns

Panthi

2018

Hydro Nepal

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Tunnels and underground caverns located at greater depth (high rock cover or overburden) are subjected to high in-situ stress environment. Those rock mass that are relatively unjointed and massive are exposed to the brittle failure, which is famously known as rock spalling/ rock bursting phenomenon. Establishing state of the stress and evaluating stress-induced instability in tunnels passing through such rock mass at relatively greater depth is therefore a challenge. The aim of this manuscript is to describes existing brittle failure (rock burst) prediction methods that are being practiced worldwide and propose necessary editions so that quality of assessment is enhanced. The methods described are very practical and the author is confident that professional engineers will use them to evaluate and predict potential rock burst/ rock spalling scenario in the tunnels during planning, design and construction phases. Each method of prediction is explained, applicability extent is highlighted and comparisons between the methods are made.

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Estimating the potential for spalling around a deep nuclear waste repository in crystalline rock

Cited by 257 publications

References 13 publications

Study on the Progressive Failure Characteristics of Coal in Uniaxial and Triaxial Compression Conditions Using 3D-Digital Image Correlation

Study on the Progressive Failure Characteristics of Coal in Uniaxial and Triaxial Compression Conditions Using 3D-Digital Image Correlation

Detection of Cracking Levels in Brittle Rocks by Parametric Analysis of the Acoustic Emission Signals

Methods Applied in the Prediction of Brittle Failure in Tunnels and Underground Caverns

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