Micro-scale deformation of gypsum during micro-indentation loading

Hogan, James D.; Boonsue, Suporn; Spray, John G.; Rogers, Robert J.

doi:10.1016/j.ijrmms.2012.05.028

Cited by 9 publications

(8 citation statements)

References 67 publications

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“…Using the initial wave velocity before the blasting test of each monitoring section, the damage degree of gypsum rocks at different depths of each section with different blasting times can be analysed. According to previous results [21,22],…”

Section: Damage Degreesupporting

confidence: 56%

Damage Mechanism and Stress Distribution of Gypsum Rock Pillar Subjected to Blasting Disturbance

et al. 2022

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The room-pillar mining technology of underground gypsum resources results in numerous gypsum rock pillars for controlling and supporting mined gobs, which forms a large area of roof hanging gobs. Owing to weathering and mining activities, gypsum rock pillar damage and failure will occur, thereby inducing a large area of gypsum mined-gob collapse accidents and disasters. Blasting is vital to the stability of gypsum rock pillars and is indispensable in mining engineering. Based on field blasting tests and using wave velocity as the basic parameter to characterise the integrity of gypsum rock, the damage mechanism of gypsum rock pillars subjected to blasting disturbance is investigated. With ten blasting tests, the maximum damage rate is 7.82% along the horizontal direction of pillar, and 3.52% along the vertical direction. The FLAC numerical simulation calculation software is used to analyse the stress distribution law of gypsum rock pillars with disturbances of different strengths from different distances. As the disturbance strength increased, the stress increased with no clear linear relationship; as the disturbance distance increased, the stress decreased gradually with a linear relationship. All stress after disturbance is greater than the original static stress, and lower than the ultimate compressive strength. However, the correlation between blasting tests results and numerical simulation results is poor and is discussed for many factors. The results can provide important guidance and reference for clarifying the damage mechanism of gypsum rock pillars subjected to blasting disturbance, as well as reveal the collapse mechanism of gypsum mined gobs.

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Section: Damage Degreesupporting

confidence: 56%

Damage Mechanism and Stress Distribution of Gypsum Rock Pillar Subjected to Blasting Disturbance

et al. 2022

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“…Our study shows single crystal gypsum has a higher average hardness (1.8–2.7 GPa) than polycrystalline gypsum reported through mesoscale compressive test experiments (23–70 MPa) (Heard & Rubey, 1966; Milsch & Scholz, 2005). The high load ( P max = 5N) microindentation experiments also reported lower hardness, 0.89 GPa (Hogan et al., 2012), which is likely due to increased defects (dislocations, microcracks and pore spaces) when scaling from micro to mesoscale.…”

Section: Discussionmentioning

confidence: 97%

Insights Into the Micromechanics of Dehydration‐Induced Gypsum to γ‐Anhydrite Phase Transition From Instrumented Microindentation Experiments

Mukherjee,

Misra

2024

JGR Solid Earth

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Gypsum, an anisotropic hydrous mineral, localizes strain through dehydration‐induced embrittlement and hydrodynamic lubrication, affecting the deformation in active tectonic settings. Here, we examine the micromechanical status of syn‐ and post‐dehydration gypsum‐phases, crucial for understanding intra‐crystalline deformation. We micro‐indented the (010) planes of natural gypsum crystals from 30 to 140°C at various strain‐rates to track mechanical changes during progressive dehydration and phase transition. Thermogravimetric analyses reveal that gypsum dehydrates between 100 and 140°C following a sigmoidal curve. Micromechanical data show, at 30°C, the mean hardness of gypsum is 2.42 GPa, reducing to 0.5 GPa at 140°C, after complete dehydration. Following the sigmoidal dehydration trend, elastic modulus, fracture toughness, and yield stress likewise drops with progressive dehydration. The Gypsum‐Hemihydrate phase exhibits strain‐rate sensitive elastoplastic deformation between 30 and 110°C, as hardness decreases with increasing strain‐rate. We propose that delamination of the layers and extensive tensile cracking along [010] cause this strain‐rate sensitive behavior, displaying Indentation Size Effect. Dehydrated phases (Hemihydrate and γ‐Anhydrite) are formed as exfoliated pseudomorphic flakes through topotactic transformation along [010] and show two sets of oppositely dipping slip systems. During the late dehydration stage (120–140°C), plastic strain is accommodated by the sliding of these flakes along with inelastic pore compaction, resulting in strain‐rate insensitive plastic deformation of the system.

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“…Both of them are of great significance to the mechanism research, optimization of operation parameters and process of mechanical tools for rock fragmentation. At present, a large number of studies on the indenter intrusion process have been proposed for different geometries of indenters such as spherical, pyramidal, conical and flat-ended cylindrical indenters through theoretical, numerical and experimental methods [20][21][22][23]. Elastic mechanics is the most common theoretical approach for studying the deformation and stress field of rocks [24][25][26][27].…”

Section: The 3d Uniaxial Compression Simulationmentioning

confidence: 99%

Numerical Study on the Elastic Deformation and the Stress Field of Brittle Rocks under Harmonic Dynamic Load

Tian

Kapitaniak³

et al. 2020

Energies

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In order to study the deformation displacement and the stress field of brittle rocks under harmonic dynamic loading, a series of systematic numerical simulations are conducted in this paper. A 3D uniaxial compression simulation is carried out to calibrate and determine the property parameters of sandstone and a model of the cylindrical indenter intruding the rock is proposed to analyze the process of elastic deformation. Four main parameters are taken into account, namely the position on the rock, the frequency and the amplitude of dynamic load, the type of indenter and the loading conditions (static and static-dynamic). Based on the analysis undertaken, it can be concluded that both of the deformation displacement and stress field of the rock change in a harmonic manner under the static-dynamic loads. The frequency and the amplitude of harmonic dynamic load determine the period and the magnitude of the rock response, respectively. In addition, the existence of harmonic dynamic load can aggravate the fatigue damage of the rock and allow a reduction in static load. Our investigations confirm that the static-dynamic loads are more conducive to rock fracture than static load.

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Micro-scale deformation of gypsum during micro-indentation loading

Cited by 9 publications

References 67 publications

Damage Mechanism and Stress Distribution of Gypsum Rock Pillar Subjected to Blasting Disturbance

Damage Mechanism and Stress Distribution of Gypsum Rock Pillar Subjected to Blasting Disturbance

Insights Into the Micromechanics of Dehydration‐Induced Gypsum to γ‐Anhydrite Phase Transition From Instrumented Microindentation Experiments

Numerical Study on the Elastic Deformation and the Stress Field of Brittle Rocks under Harmonic Dynamic Load

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