WEBOct 10, 2022 · Permeability changes with confining stress loading–unloading: (a) is the PUC; (b) is the aclastic coal; (c) is the mylonitic coal; (d) is the loading–unloading process of confining stress. The increase in confining pressure compressed the coal matrix and internal fissures of the coal cores, and their permeability rapidly and then slowly ...
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WEBJan 1, 2020 · In the coal mining process, the stress state of the coal seam will change due to unloading caused by coal mininginduced, which may lead to the occurrence of coal and gas outburst disasters.
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WEBApr 18, 2024 · The loading process can be divided into four stages, as seen in Fig. 6 a: (1) initial loading, (2) unloading of σ 3, (3) stress concentration, and (4) the coal burst stages. The initial stress level was applied by multistage loading (the initial stress σ 0 has three grades). When the stress reaches the designed value, it will remain constant ...
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WEBJul 31, 2017 · The repeated mining causes the unloading and loading of the caved zone, so that the pore structures of caved zone change accordingly, and thus affect the permeability value, which controls the gas migration in the caved zone. The main factors affecting the permeability of the unloading process are different from those controlling .
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WEBNov 1, 2023 · To further validate and promote the proposed damage constitutive model, the loadingunloading process of coal material is also simulated. Because energy is continuously transformed during loading, in the loadingunloading process, the damage variable is also defined by energy dissipation.
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WEBSep 1, 2021 · For cyclic unloading, a lower unloading rate is beneficial to the compression of tectonic coal in the initial unloading stage. Previous experimental results have shown that the permeability of the ...
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WEBJan 7, 2023 · By testing permeability during the loading and unloading process of coal samples, key parameters of the fractional permeability model were obtained to enter specific values into the model to ...
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WEBAs the coal body has a hysteresis effect during the unloading process, it cannot be unloaded to 0 when unloading, and the minimum unloading level was set for the four kinds of samples; that is, after unloading to 2% σ c, the loading was performed until the sample was destabilized.
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WEBMay 27, 2022 · The loading process of CRCS under biaxial compression experienced four ... which has resulted in the rapid unloading of stress in coal and rock. A high unloading speed of 10 m/s of horizontal stress was used to investigate the effects of a much higher unloading speed on the failure and instability of the CRCS according to the speed set ...
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WEBApr 1, 2024 · During the loading process, the common loading method is constant displacement loading, such as mm/min, etc. ... 2019c, Zhang et al., 2019d studied the effect of three cycles of loading and unloading on the permeability of broken coal sample based on the impact of multiple loading and unloading on the goaf during the mining .
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WEBJan 23, 2021 · On the premise that the point of the maximum abutment pressure is the demarion point of gas migration, an experimental research was conducted on gasbearing coal by using a thermofluid–solid coupling test system. The research results demonstrate that irreversible strain and elastic modulus increase with increase in .
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WEBSep 1, 2020 · The energy evolution and fragment distribution characteristics of different types of rocks were investigated through the uniaxial cyclic loading and unloading experiments for granite, redsandstone, coal, gypsum, and highwater material. Based on the results of the study, the following conclusions are drawn.
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WEBJun 1, 2020 · As the coal body has a hysteresis effect during the unloading process, it cannot be unloaded to 0 when unloading, and the minimum unloading level was set for the four kinds of samples; that is, after unloading to 2% σ c, the loading was performed until the sample was destabilized.
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WEBOct 8, 2019 · Discussion on bulk carrier loading and unloading operations and freight safety for the owner's and master's responsibilities and obligations as per charter Party requirements. Master's Thesis, Department of Shipping Technology, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan, 2018.
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WEBNov 30, 2018 · Moreover, pressure relief mining produces loading and unloading processes in the protected coal seam, and we also find the permeability heavily depends on the loading or unloading process, ...
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WEBFeb 27, 2023 · The damage and fracture of coal is accompanied by a complex energy conversion process, and these different stages of energy evolution are closely related to coal failure. In this paper, an evolution model describing the behavior of coal failure was proposed using the energy dissipation under cyclic loading/unloading. The energy .
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WEBJun 28, 2023 · Some of the activities related to loading and unloading include: Loading. Loading involves the process of loading cargo into a transport vehicle, such as a truck or container. This involves efficiently and safely managing loads within the vehicle to prevent damage or loss during transportation. Demolition. Unloading is the activity of removing ...
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WEBAug 1, 2019 · The results showed that the change trend of permeability was negatively correlated with the confining pressure in the process of loading/unloading of coal and it was divided into three stages for ...
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WEBNov 15, 2018 · Abstract and Figures. In this article the process of coal unloading from the face's fracture zone to the conveyor using shearer drums is presented. The effect of the form and dimensions of the ...
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WEBUnloading and loading freight happens so often that workers and management can become complacent to the inherent dangers that exist in the process. Unloading and loading freight is almost always under some sort of time constraint. This issue and tighter supply chain windows can exacerbate the problem and create an even more dangerous .
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WEBResearch on energy and damage evolution patterns of gascontaining coal under constricting pressure unloading conditions is urgently needed in the process of deep underground mining and is crucial for understanding the mechanisms underlying coal and gas composite rockburst occurrences. Prior reaching peak stress, cyclic loading and .
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WEBMay 14, 2024 · This study investigates the stability of an artificial dam used in an underground reservoir in a coal mine under periodic weighting imposed by overlying rock strata. For this purpose, cyclic loading and unloading tests with different stress amplitudes were designed. Differences in the mechanical performance of the artificial dam with and .
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WEBJul 11, 2022 · The change of elastic modulus of coal samples with the moisture. content of % is the largest in the first and sixth cyclic loading–unloading, decreasing. Mpa and Mpa ...
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