Effect of the Minor Principal Stress on Crack Initiation Stress Threshold

Mutaz, E.; Serati, Mehdi; Williams, David J.

doi:10.1088/1755-1315/861/4/042013

Cited by 3 publications

(9 citation statements)

References 20 publications

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“…An initial seating load of 5 KN was maintained in the 𝜎 1 , 𝜎 2 , and 𝜎 3 directions to prevent the specimens becoming off-center during testing and a loading rate of 15 kN/min (or 0.1 MPa/s) was applied, with the stresses increased simultaneously from the seating load of 5 KN to the designated 𝜎 2 and 𝜎 3 stresses given in Table 2 under both room temperature and 100°C. Figure 3 presents the variation of 𝜎 1 with 𝜎 2 under a constant value of 𝜎 3 at 100°C compared to the room temperature results reported in [9].…”

Section: Methodsmentioning

confidence: 99%

“…To meet such increasing demand, underground and open-pit mines have advanced to greater depths. At depth, the surrounding environment of high pressure and high temperature, in addition to lower porosity, leads to explosion-like fractures without any pre-warning, either in a severe way like rockburst or in a less severe way like stress spalling and slabbing [1]. Rockburst and spalling involve the catastrophic failure of brittle rocks around underground openings and is a global challenge that endangers tunnelling and mining operations, damages equipment, and causes injuries and fatalities among the workforce.…”

Section: Introductionmentioning

confidence: 99%

“…In some cases, failure could be time-dependant, such as the incidents reported at the Jinping II Hydropower Station tunnel in China during 2010 [2]. Spalling failure has been reported in Nickel mines in the Sudbury Basin in Canada, the Neyriz Marble Mine in Iran, Champion Reef Mine in India, the Hongtoushan copper mine in China, the Garpenberg zinc mine in Sweden, and the Newport Formation in the Sydney Basin in Australia [3,4,5,6,7,8,9], among others. While spalling is very common in highly-stressed crystalline rocks in deep tunnels and mines, it may also happen in shallow lightly-cemented, or porous rocks like sandstone under low confinement [10].…”

Section: Introductionmentioning

confidence: 99%

“…Different techniques were developed recently to determine the CI also based on stress-strain behaviour, such as: optical diffraction, laser speckle interferometry, ultrasonic probing, digital image processing, and acoustic emission (AE) [1,16]. However, laser and digital image processing are very sensitive to temperature fluctuations or electrical resistivity variations.…”

Section: Introductionmentioning

confidence: 99%

“…However, laser and digital image processing are very sensitive to temperature fluctuations or electrical resistivity variations. At the same time, the AE method could not always quantify the background noise in damage assessments and thus make them less favourable [1,17,18]. Moving up the stress-strain curve and well beyond the CI stage, the underground rock tends to deform in a plastic fashion in which cracks grow abruptly in a so-called crack damage (CD) stage.…”

Section: Introductionmentioning

confidence: 99%

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Coupled Thermo-Mechanical Study of Crack Initiation Stress Threshold in Porous Sandstone

Moravej

Mutaz²,

Serati³

et al. 2023

IOP Conf. Ser.: Earth Environ. Sci.

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The increasing depth of tunnels and underground mining operations worldwide has resulted in the rise of deep mines at temperatures well above 50°C. Such unwanted thermal gradients not only adversely impact the physical and mechanical behaviours of the rock mass but could also affect the safety of underground mines leading to temporarily and permanently shutting down the operation. The combination of high temperature and high-stress conditions further culminates in explosion-like fractures like rockburst and spalling, which are the main problems in deep mining and tunnel constructions. Spalling is identified as an abrupt explosion-like rock failure that occurs spontaneously and can endanger tunnelling and mining operations, causing injuries and fatalities, and necessitating investigation of the effect of temperature on rock behaviour. It is known that the spalling strength is correlated with the internal crack initiation in low-porosity and brittle crystalline rocks. This paper investigates this phenomenon and examines the influence of coupled thermo-mechanical conditions on the crack initiation stress level of sandstone samples. True triaxial compression tests were carried out on 50 mm sandstone cubes from room temperature (25°C) to 100°C using a high temperature true triaxial testing facility. The results suggest that temperature can have a significant impact on crack initiation and the spalling strength of rock, particularly at low confinement.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Coupled Thermo-Mechanical Study of Crack Initiation Stress Threshold in Porous Sandstone

Moravej

Mutaz²,

Serati³

et al. 2023

IOP Conf. Ser.: Earth Environ. Sci.

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Crack mode-changing stress level in porous rocks under polyaxial stress conditions

2023

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As the global push towards clean energy intensifies, the demand for critical minerals has driven deep excavation in hard rock formations, posing significant challenges related to rockburst and spalling. Spalling refers to explosion-like rock fractures under high geo-stresses. Despite several successful studies and practical models, the mechanisms governing spalling propagation under polyaxial stress states remain inadequately understood, particularly in weaker and high-porosity rocks. This study introduces a novel Crack Mode-Changing Stress (CMCS) concept, which defines the minimum principal stress required to change the crack mode from shear to tensile failures when rock spalls. The concept was validated using cubed sandstone samples containing centric circular holes subjected to a range of loading conditions including uniaxial, biaxial, generalized triaxial compression, generalized triaxial tensile, and true triaxial loading stress states. Our results highlight the significance of the out-of-plane minor principal stress on the crack initiation threshold and the CMCS, emphasizing the need for careful consideration when designing openings in highly stressed environments.

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Synergies between Heat- and Stress-Induced Spalling Theory Applied to Rock and Concrete in Tunnel Applications

Saha

Serati

Maluk

et al. 2023

IOP Conf. Ser.: Earth Environ. Sci.

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Fire-induced and stress-driven catastrophic failures in rock and concrete are commonly known as spalling (or rockburst in its severe form) that have jeopardised the safety of personnel, seriously damaged rock structures, and shut down operations for months or even permanently in certain circumstances. Particularly in Australia, spalling and rockburst in deep excavations results in a heavy toll on mine safety and have become a constraint to the economic viability of several Australian deep mines since the early 1950s. The prevailing industry approach is to treat such unwanted failures and associated microseismic events as a result of insufficient energy absorption by the spalling-prone rock/concrete at the post-peak stage. However, this approach does not allow efficient handling of heat- or stress-induced failures as it requires an in-depth understanding of their mechanics. Prediction of these events based on the available failure criteria does not help either due to the numerous criteria involved and the difficulty in determining their parameters at the excavation scale. A proper understanding of the fracture growth in such failures is needed to understand the behaviour of rock or concrete structures resulting in a sudden release of energy at deep excavations. This paper investigates the similarities and differences between heat-induced concrete spalling and stress-driven rockburst and further examines the effect(s) of material, geometrical, geological properties, and the applied deviatoric stresses on these failure modes.

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Effect of the Minor Principal Stress on Crack Initiation Stress Threshold

Cited by 3 publications

References 20 publications

Coupled Thermo-Mechanical Study of Crack Initiation Stress Threshold in Porous Sandstone

Coupled Thermo-Mechanical Study of Crack Initiation Stress Threshold in Porous Sandstone

Crack mode-changing stress level in porous rocks under polyaxial stress conditions

Synergies between Heat- and Stress-Induced Spalling Theory Applied to Rock and Concrete in Tunnel Applications

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