Energy Evolution of Anthracite Considering Anisotropy Under High Confining Pressure: An Experimental Investigation

Wang, Xiaoliang; Zhao, Yixin; Gao, Yirui; Sun, Zhuang; Liu, Bin; Jiang, Yaodong

doi:10.1007/s00603-023-03398-w

Cited by 5 publications

(1 citation statement)

References 91 publications

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“…The deformation and failure of samples are fundamentally unstable phenomena resulting from energy transformation, which encompasses the energy accumulation, dissipation, and instantaneous release [23]. During cyclic loading and unloading, the axial stress applies positive work to compress the coal sample, causing it to store energy through elastic deformation.…”

Section: Energy Evolution Characteristicsmentioning

confidence: 99%

Mechanical Behaviors and Precursory Characteristics of Coal-Burst in Deep Coal Mining for Safety-Sustainable Operations: Insights from Experimental Analysis

Wang,

Zhou

et al. 2024

Sustainability

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Coalburst, a frequent and severe dynamic disaster, poses significant challenges to the safety and sustainable development of coal mines during deep excavation. To investigate the mechanical behaviors and precursory characteristics of coalburst subjected to in situ stress conditions, multiaxial cyclic loading experiments were conducted on cubic coal specimens, and the effects of different confining pressures on the mechanical parameters and energy evolution were analyzed. Acoustic emission (AE) technology was utilized to study the accumulation process of stress-induced damage and identify the source modes of microcracks. Then, nonlinear fractal theory and critical slowing theory were used to investigate the time-varying precursory characteristics of catastrophic failure in coalburst. The results show that as the confining pressure increases, the coal samples exhibit higher levels of elastic strain energy and dissipative energy, indicating an enhancement of plasticity. The AE count and accumulated energy show a strong correlation with cyclic loads. With an increasing number of cycles, the AE Felicity ratio gradually decreases, indicating a progressive increase in irreversible damage. Shear-mode microcracks also become more prominent with applied stress and confining pressures, as supported by varying AF/RA values of AE signals. The AE signals also follow the Hurst statistical law, and increasing applied stress and confining pressure strengthen this statistical pattern with a higher Hurst index. Throughout the cyclic loading process, certain AE varying trends were observed: the autocorrelation coefficient increased, the fractal dimension gradually decreased, and the variance suddenly increased. These trends serve as early, middle, and short–imminent warning signals, respectively, for the catastrophic failure of the loaded coal sample. These research findings contribute to a deeper understanding of coal failure evolution and provide a basis for early detection and warning of coalburst disasters, which are also essential for promoting the safe and sustainable development of deep coal mining operations.

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Section: Energy Evolution Characteristicsmentioning

confidence: 99%

Mechanical Behaviors and Precursory Characteristics of Coal-Burst in Deep Coal Mining for Safety-Sustainable Operations: Insights from Experimental Analysis

Wang,

Zhou

et al. 2024

Sustainability

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Experimental study on the physical and mechanical properties of carbonatite rocks under high confining pressure after thermal treatment

Yang,

Wang,

Yao

et al. 2024

Deep Underground Science and Engineering

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Oil and gas exploration studies have been increasingly moving deeper into the earth. The rocks in deep and ultra‐deep reservoirs are exposed to a complex environment of high temperatures and large geo‐stresses. The Tarim oilfield in the Xinjiang Uygur Autonomous Region (Xinjiang for short), China, has achieved a breakthrough in the exploration of deep hydrocarbon reservoirs at a depth of over 9000 m. The mechanical properties of deep rocks are significantly different from those of shallow rocks. In this study, triaxial compression tests were conducted on heat‐treated carbonatite rocks to explore the evolution of the mechanical properties of carbonatite rocks under high confining pressure after thermal treatment. The rocks for the tests were collected from reservoirs in the Tarim oilfield, Xinjiang, China. The experiments were performed at confining pressures ranging from atmospheric to 120 MPa and temperatures ranging from 25 to 500°C. The results show that the critical confining pressure of the brittle–ductile transition increases with increasing temperature. Young's modulus is negatively correlated with the temperature and positively correlated with the confining pressure. As the confining pressure increases, the failure mode of the specimens gradually transforms from shear fracture failure into “V”‐type failure and finally into bulging failure (multiple shear fractures). With increasing temperature, the failure angle tends to decrease. In addition, an improved version of the Mohr‒Coulomb strength criterion with a temperature‐dependent power function was proposed to describe the failure strength of carbonatite rocks after exposure to high temperature and high confining pressure. The surface of the strength envelope of this criterion is temperature dependent, which could reflect the strength evolution of rock under high confining pressures after thermal treatment. Compared with other strength criteria, this criterion is more capable of replicating physical processes.

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Failure prediction and microcracks development based on acoustic emission and energy evolution for different rocks treated with freeze–thaw weathering

Ullah,

Zhou,

Cai

et al. 2023

Bull Eng Geol Environ

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Energy Evolution of Anthracite Considering Anisotropy Under High Confining Pressure: An Experimental Investigation

Cited by 5 publications

References 91 publications

Mechanical Behaviors and Precursory Characteristics of Coal-Burst in Deep Coal Mining for Safety-Sustainable Operations: Insights from Experimental Analysis

Mechanical Behaviors and Precursory Characteristics of Coal-Burst in Deep Coal Mining for Safety-Sustainable Operations: Insights from Experimental Analysis

Experimental study on the physical and mechanical properties of carbonatite rocks under high confining pressure after thermal treatment

Failure prediction and microcracks development based on acoustic emission and energy evolution for different rocks treated with freeze–thaw weathering

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