Experimental Study of Mechanical Behaviors and Failure Characteristics of Coal Under True Triaxial Cyclic Loading and Unloading and Stress Rotation

Ran, Qican; Zou, Quanle; Zhang, Bichuan; Yao, Hong

doi:10.1007/s11053-022-10022-1

Cited by 58 publications

(16 citation statements)

References 29 publications

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“…Coal, as one of the important fossil energy resources, is an essential resource in the industrialization and urbanization processes. − In recent years, shallow resources have been gradually depleted with the growing mining intensity, and deep mining has become normal. − However, deep underground mines feature great geostress and high gas concentration, so the gas content is likely to exceed the limit and gas disasters including rock and gas outbursts occur frequently. , Water injection in coal seams is one of the effective measures to control gas and has been extensively applied to coal mining. − Injecting high-pressure water in coal seams through boreholes to wet and soften coal seams before mining can distribute stress uniformly, enhance the plasticity of coal, and reduce the release of elastic potential energy, thus further eliminating or decreasing the risk of coal and gas outbursts, − whereas numerous research studies have shown that coal has strong hydrophobicity and deep coal seams have poor gas permeability, so water is difficult to absorb by coal seams. This may lead to waste of a huge amount of water resources and a poor water injection effect. − Therefore, increasing the wettability of coal seams is the key to improving the water injection effect in the coal seams.…”

Section: Introductionmentioning

confidence: 99%

Study of Time-Varying Laws of Stability and Wettability of SiO₂–H₂O Nanofluids with Different Particle Sizes

Zhao,

Tian,

Xie

et al. 2023

Ind. Eng. Chem. Res.

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It has been proven that SiO2–H2O nanofluids have great application potential for water injection in coal seams. To explore the influences of the particle size on the stability and wettability of SiO2–H2O nanofluids, sedimentation observation of nanoparticles (NPs), viscosity tests, pH tests, surface tension tests, and contact angle tests were performed for SiO2–H2O nanofluids with different particle sizes. The research shows that the larger the particle size of SiO2 NPs, the more obvious the aggregation and sedimentation of NPs. The smaller the particle size of SiO2 NPs is, the lower the surface tension and contact angle of the SiO2–H2O nanofluids. As time goes on, SiO2–H2O nanofluids successively show time-varying characteristics in the low stability stage, moderate stability stage, and high stability stage. Therein, the low stability stage is the optimal period for enhancing the water injection in coal seams by nanofluids. The research provides theoretical support for using SiO2–H2O nanofluids to enhance water injection in coal seams.

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Section: Introductionmentioning

confidence: 99%

Study of Time-Varying Laws of Stability and Wettability of SiO₂–H₂O Nanofluids with Different Particle Sizes

Zhao,

Tian,

Xie

et al. 2023

Ind. Eng. Chem. Res.

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“…Elbably et al 18 revealed the deformation and failure patterns of encased steel‐high‐strength concrete columns subjected to axial and cyclic loading. The damage and failure patterns of coal were analyzed based on true triaxial cyclic loading tests 19 . Sun et al 20 investigated the influence of water content on fatigue deformation, energy dissipation, and failure mode of concrete under compressive cyclic loads.…”

Section: Introductionmentioning

confidence: 99%

“…The damage and failure patterns of coal were analyzed based on true triaxial cyclic loading tests. 19 Sun et al 20 investigated the influence of water content on fatigue deformation, energy dissipation, and failure mode of concrete under compressive cyclic loads. The dynamic compression properties, damage, and fracture patterns of sandstone after freeze-thaw cycles were analyzed.…”

Section: Introductionmentioning

confidence: 99%

Failure characteristic and acoustic emission spatio‐temporal evolution of coal under different cyclic loading rates

Liu

Zhao

Hua

et al. 2023

Energy Science & Engineering

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The coal and rock dynamic disasters occur more and more frequently in deep mining, which is tightly correlated to the instability of coal pillars under high stress and cyclic disturbance load. In this study, the strength, deformation behaviors, and failure mechanism of coal under cyclic loading in a high-stress state were investigated by considering the influence of cyclic loading rate. The experimental results indicate that the compressive strength is positively correlated with the cyclic loading rate, and the deformation patterns, AE amplitude, and spatial evolution are the same under various cyclic loading rates. The damage variable shows the "slow increase→fast increase→slow increase→ fast increase →slow increase→fast increase→rapid increase" trend.The damage growth rate ranges from 9.32 × 10 −5 to 4.86 × 10 −3 , and increases with the cyclic loading rate. The spatial fractal dimensions under various cyclic loading rates are the same, and the distribution ranges from 2.1 to 2.9, showing a general downward trend. The microfailure mechanism under various cyclic loading rates is mixed failure dominated by tensile failure, with a small amount of shear failure. There is a positive correlation between the percentage of shear cracks and the cyclic loading rates.

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“…43,44 This complicates the various instability and failure mechanisms of coal mass. To reveal the mechanical response of coal during various loading conditions, many investigations were thus implemented, such as the impact load experiment conducted by Hopkinson compression bar, 45,46 uniaxial or triaxial compressive cyclic loading and unloading experiments, 47,48 and rock mechanics experiments with different loading paths. 49 Compared with the loading approaches mentioned above, the cyclic loading-unloading testament is an effective approach in revealing the mechanical response of coal and rock under repeated disturbance of excavation, 47,50,51 through parameters, such as peak strength, elastic modulus, and energy dissipation features.…”

Section: Introductionmentioning

confidence: 99%

Effect of water on the damage and energy dissipation feature of coal under uniaxial cyclic loading–unloading condition

Song,

Zhao,

et al. 2023

Energy Science & Engineering

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To gain insight into the reduction mechanism of water on the dynamic destabilization failure character of coal under mining disturbance conditions, the effect of water on the damage and energy dissipation feature of coal was investigated via cyclic uniaxial compressive loading–unloading test, acoustic emission (AE) monitoring technology, and theoretical analysis. It manifests that the softening effect of water on the mechanical properties of coal is still remarkable, lower uniaxial compressive strength and elastic modulus, while greater axial strain and higher Poisson's ratio are observed under the cyclic loading–unloading condition. Water‐saturated specimens dissipate more energy during the cyclic loading–unloading process, which reduces the proportion of input energy accumulated in the coal mass, thus lowering the burst proneness of coal. A greater amount of damage generates in air‐dried specimens than that in water‐saturated specimens at the first cyclic loading–unloading cycle, while lower damage increments are observed in the following cycles. This may be the reason for the minimal energy dissipation of air‐dried specimens in the following cycles. The elastic modulus behaves logarithmically versus the increasing cyclic loading–unloading cycle counts. The energy dissipated due to the damage evolution and plastic deformation of coal specimens positively correlates with the energy released by AE activities, the AE energy in air‐dried specimens has a greater concentration around the peak axial stress and a stronger correlation with the dissipated energy. The cumulative AE energy and energy dissipation density are linearly correlated during the cyclic loading–unloading process, which indicates a possibility in estimating the damage evolution and the dynamic failure risk of coal via cumulative AE energy, under the cyclic loading–unloading condition.

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Experimental Study of Mechanical Behaviors and Failure Characteristics of Coal Under True Triaxial Cyclic Loading and Unloading and Stress Rotation

Cited by 58 publications

References 29 publications

Study of Time-Varying Laws of Stability and Wettability of SiO₂–H₂O Nanofluids with Different Particle Sizes

Study of Time-Varying Laws of Stability and Wettability of SiO₂–H₂O Nanofluids with Different Particle Sizes

Failure characteristic and acoustic emission spatio‐temporal evolution of coal under different cyclic loading rates

Effect of water on the damage and energy dissipation feature of coal under uniaxial cyclic loading–unloading condition

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Experimental Study of Mechanical Behaviors and Failure Characteristics of Coal Under True Triaxial Cyclic Loading and Unloading and Stress Rotation

Cited by 58 publications

References 29 publications

Study of Time-Varying Laws of Stability and Wettability of SiO2–H2O Nanofluids with Different Particle Sizes

Study of Time-Varying Laws of Stability and Wettability of SiO2–H2O Nanofluids with Different Particle Sizes

Failure characteristic and acoustic emission spatio‐temporal evolution of coal under different cyclic loading rates

Effect of water on the damage and energy dissipation feature of coal under uniaxial cyclic loading–unloading condition

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Study of Time-Varying Laws of Stability and Wettability of SiO₂–H₂O Nanofluids with Different Particle Sizes

Study of Time-Varying Laws of Stability and Wettability of SiO₂–H₂O Nanofluids with Different Particle Sizes