Effects of Grain Size on the Initiation and Propagation Thresholds of Stress-induced Brittle Fractures

Eberhardt, E.; Stimpson, Brian; Stead, D.

doi:10.1007/s006030050026

Cited by 305 publications

(133 citation statements)

References 22 publications

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“…These observations are in agreement with several studies of the formation of microcracks from UCS tests (e.g. [4,27]). According to Åkesson et al [4], a moderate alteration of feldspars gives the mineral grains a more ductile behaviour that reduces stress concentration and cracking of the feldspar grains, which may partly explain why Vandle is stronger than Avja and LEP.…”

Section: Mineral Compositionssupporting

confidence: 93%

“…The microstructure of rock is known to influence its strength and deformation characteristics. Eberhardt et al [27] showed that the grain size had a significant effect in controlling the behaviour of the cracks once they began to propagate. That is why the crack propagations in microstructural modelling have more tortuous paths than those in micromechanical modelling because the grain size in microstructural modelling in this study is relatively bigger compared with the size of the specimen.…”

Section: 22mentioning

confidence: 99%

“…Therefore, the grain size has a big influence on the aggregate breakage properties. According to Eberhardt et al [27], the grain size has a significant effect in controlling the crack propagation behaviour. Actually, from the modelled fracture processes, more tortuous crack propagation paths are observed in the microstructural modelling compared with those in the micromechanical modelling.…”

Section: Microstructural Modelling and Micromechanical Modellingmentioning

confidence: 99%

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Characterisation of rock aggregate breakage properties using realistic texture‐based modelling

Liu

Lindqvist

Åkesson³

et al. 2011

Num Anal Meth Geomechanics

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SUMMARYRealistic texture-based modelling methods, that is microstructural modelling and micromechanical modelling, are developed to simulate the rock aggregate breakage properties on the basis of the rock actual microstructure obtained using microscopic observations and image analysis. The breakage properties of three types of rocks, that is Avja, LEP and Vandle taken from three quarries in Sweden, in single aggregate breakage tests and in inter-aggregate breakage tests are then modelled using the proposed methods. The microstructural modelling directly integrates the microscopic observation, image analysis and numerical simulation together and provides a valuable tool to investigate the mechanical properties of rock aggregates on the basis of their microstructure properties. The micromechanical modelling takes the most important microstructure properties of rock aggregates into consideration and can model the major mechanical properties. Throughout this study, it is concluded that in general, the microstructure properties of rock aggregate work together to affect their mechanical properties, and it is difficult to correlate a single microstructure property with the mechanical properties of rock aggregates. In particular, for the three types of rock Avja, LEP and Vandle in this study, crack size distribution, grain size and grain perimeter (i.e. grain shape and spatial arrangement) show good correlations with the mechanical properties. The crack length and the grain size negatively affect the mechanical properties of Avja, LEP and Vandle, but the perimeter positively influences the mechanical properties. Besides, the modelled rock aggregate breakage properties in both single aggregate and inter-aggregate tests reveal that the aggregate microstructure, aggregate shape and loading conditions influence the breakage process of rock aggregate in service. For the rock aggregate with the same microstructure, the quadratic shape and good packing dramatically improve its mechanical properties. During services, the aggregate is easiest to be fragmented under point-to-point loading condition, and then in the sequence of multiple-point, point-to-plane and plane-to-plane loading conditions. Copyright

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Section: Mineral Compositionssupporting

confidence: 93%

Section: 22mentioning

confidence: 99%

Section: Microstructural Modelling and Micromechanical Modellingmentioning

confidence: 99%

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Characterisation of rock aggregate breakage properties using realistic texture‐based modelling

Liu

Lindqvist

Åkesson³

et al. 2011

Num Anal Meth Geomechanics

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“…Fracturing of brittle rock is a process through which existing bonds are broken and new surfaces are created (Eberhardt et al 1999). Because failure begins by breaking the inter-granular bonds, the microstructure of a rock has a significant influence on the fracture progression behavior.…”

Section: Fracture Progression In Brittle Rockmentioning

confidence: 99%

“…Failure of brittle rock is progressive, although it appears to be sudden in many cases, and a number of studies have been devoted to the characterization of the fracture propagation behavior of different rock types (e.g. Eberhardt et al 1999;Scholz 1968;Martin and Chandler 1994;Peng and Johnson 1972). Although efforts have been made to correlate the strength and deformational properties with joint geometrical parameters, since the fracture progression behavior of jointed rock has been scarcely studied, the effects of joint geometrical properties on the fracture progression behavior of jointed rock are not well understood.…”

Section: Introductionmentioning

confidence: 99%

Do joint geometrical properties influence the fracturing behaviour of jointed rock? An investigation through joint orientation

Wasantha

Ranjith

Zhang

et al. 2015

Geomech. Geophys. Geo-energ. Geo-resour.

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Failure of brittle rock is often progressive and understanding the fracture development process within rock masses is important to identify the precursors of failures. Joints in rock masses influence the fracture progression behavior and we studied the influence of joint orientation on fracture progression in jointed rock. Undrained triaxial tests were conducted on 54 mm diameter and 108 mm high intact and singly-jointed sandstone specimens. The joints in jointed specimens were made rough (joint roughness coefficient = 10-12) and embedded in six different orientations-0°, 30°, 45°, 60°, 75°and 90°-and three different combinations of confining and initial pore-water pressures were considered (confining pressure/pore-water pressure = 4/1, 10/4 and 25/10 MPa). An acoustic emission (AE) monitoring system was employed during all tests to monitor the fracture development within the test specimens. The post-failure patterns of specimens displayed three different failure mechanisms-shearing through intact material, sliding along the joint and a mixture of both shearing and sliding-depending on the joint orientation and confining pressure. The fracture progression behavior of the specimens showed a strong correlation with these failure mechanisms. Intact specimens and specimens with joints oriented at 0°, 30°, 90°failed by shearing. Nevertheless, the AE patterns of intact specimens and specimens with 90°-oriented joints contrasted with those of specimens with joints oriented at 0°a nd 30°. Specimens with joints oriented at 60°failed by sliding with a constant rate of acoustic event generation starting from the beginning of deviatoric loading. A mixed failure mechanism was observed for specimens with joints oriented at 45°and 75°. While the characteristics of both sliding and shearing failure were observed from the AE patterns of both 45°and 75°orientations, the shearing failure component of the 75°case was found to be a result of experimental limitations rather than real behavior. Finally, we propose a family of typical AE curves to assist with the characterization of the fracture progression behavior of jointed rock by taking confining pressures and failure mechanisms into consideration.

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Thermal stress weathering and the spalling of Antarctic rocks

et al. 2017

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Using in situ field measurements, laboratory analyses, and numerical modeling, we test the potential efficacy of thermal stress weathering in the flaking of millimeter‐thick alteration rinds observed on cobbles and boulders of Ferrar Dolerite on Mullins Glacier, McMurdo Dry Valleys (MDV). In particular, we examine whether low‐magnitude stresses, arising from temperature variations over time, result in thermal fatigue weathering, yielding slow crack propagation along existing cracks and ultimate flake detachment. Our field results show that during summer months clasts of Ferrar Dolerite experience large‐temperature gradients across partially detached alteration rinds (>4.7°C mm−1) and abrupt fluctuations in surface temperature (up to 12°C min−1); the latter are likely due to the combined effects of changing solar irradiation and cooling from episodic winds. The results of our thermal stress model, coupled with subcritical crack growth theory, suggest that thermal stresses induced at the base of thin alteration rinds ~2 mm thick, common on rocks exposed for ~105 years, may be sufficient to cause existing cracks to propagate under present‐day meteorological forcing, eventually leading to rind detachment. The increase in porosity observed within alteration rinds relative to unaltered rock interiors, as well as predicted decreases in rind strength based on allied weathering studies, likely facilitates thermal stress crack propagation through a reduction of fracture toughness. We conclude that thermal stress weathering may be an active, though undervalued, weathering process in hyperarid, terrestrial polar deserts such as the stable upland region of the MDV.

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Effects of Grain Size on the Initiation and Propagation Thresholds of Stress-induced Brittle Fractures

Cited by 305 publications

References 22 publications

Characterisation of rock aggregate breakage properties using realistic texture‐based modelling

Characterisation of rock aggregate breakage properties using realistic texture‐based modelling

Do joint geometrical properties influence the fracturing behaviour of jointed rock? An investigation through joint orientation

Thermal stress weathering and the spalling of Antarctic rocks

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