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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WEBDec 1, 2020 · Fig. 9 shows that coal rocks with fracture networks of different levels of complexity all undergo essentially the same permeability evolution process under loadingunloading conditions, although differences in the final increase in permeability can be observed. The higher the complexity of the initial fracture structure is, the higher the final ...
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WEBDec 3, 2021 · As a result, the crack of saturated coal samples cannot keep stationary in the initial stage of loading and unloading and it slips throughout the loading and unloading process. A large number of macrotensile cracks appeared in the failed coal samples with pore water, as the pore pressure provides tensile force to the cracks and promotes the ...
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WEBDec 12, 2021 · 1. Introduction. With an increase in the coal mining depth, the influence of high insitu stress and high osmotic pressure on the pore structure and the permeability of surrounding rocks of the coal body in working faces has been increasingly investigated. 1 For deep underground engineering, due to the action of severe disturbances such as .
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WEBFeb 8, 2019 · Rock burst is a astrophic dynamic disaster caused by sudden failure and instability of coal, loading paths play an important role in the failure of coal, the coal failure process is associated with charge exception information. Hence, violent coal failure mechanics and time–frequency domain distribution of charge signal such as rock burst .
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WEBJan 1, 2011 · Introduction At present, coal is the preeminent fuel of thermal power plant. Continuing up the large unit, and large capacity, the demand of coal is very large. Coal need to process from loading and unloading to stockpile, this procedure can finish by coal conveying system.
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WEBJan 22, 2024 · Protective seam mining is the most economical and effective measure for eliminating coal and gas herniation. To study the unloading effect of the mining of a protective seam on the protected layer, and to better grasp the effect of the protective layer on the abatement, conventional triaxial tests were conducted on coal samples with the .
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WEBAug 12, 2021 · The coal burst is a violent failure process induced by unloading the coal seam which had been subjected to the high insitu stresses. During the unloading process, the energy stored in the coal seam and surrounding rock release rapidly, usually leading to rock burst. ... Many factors can trigger the coal burst,, the dynamic load .
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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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WEBSep 26, 2023 · The rock mass in fault zones is frequently subjected to cyclic loading and unloading during deep resource exploitation and tunnel excavation. Research on the mechanical and hydraulic characteristics of fault rock during the cyclic loading and unloading is of great significance for revealing the formation mechanism of water .
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WEBApr 28, 2017 · During the postpeak loading and unloading process, the flow rate of the coal sample will decrease with the loading of confining pressure but increase with the unloading of confining pressure, and ...
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WEBOct 15, 2022 · Under the stress loading condition, the coal matrix and fractures of PUC samples were compressed simultaneously, and the permeability was regulated by the porefissure structures in the coal matrix. ... Research on the permeability response characteristics of the stress loadingunloading process can provide some clarifiions .
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WEBMar 16, 2023 · Research on the mechanical properties and damage evolution of coal during true triaxial cyclic loading and unloading is of great significance for maintaining the longterm safety and stability of underground engineering structures in coal mines. In this paper, firstly, the deformation, strength and fracturing characteristics of coal during true triaxial .
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WEBFeb 1, 2019 · the pressure loading and unloading process was explained theoretically based on a tight fourparticle packing unit, whic h provides a reasonable explanation for the experimental results
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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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WEBFeb 15, 2024 · The overall trend indied a gradual decrease in the fractal dimension of the SPF, suggesting that the SPF within the coal were progressively fractured and permeated as the confining pressure was unloaded, thereby reducing the complexity of the SPF within the coal. (3) The complete process of unloading the confining pressure was simulated .
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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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WEBJun 1, 2019 · (3) During the loadingunloading process of confining pressure, the permeability of coal containing gas is damaged to a certain extent and this damage can be represented by the maximal damage rate ...
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WEBMay 4, 2020 · Coal mining and production activities lead to static loading and unloading changes of coal stress in front of the working face, and the stress change process has a significant influence on the ...
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WEBJun 1, 2019 · The fitting formulas of coal sample axial and radial permeability values under three loading/unloading cycles are shown in Table 5. In Table 5, subscripts A and R respectively denote the axial and radial permeability of coal samples; L and U denote loading and unloading, respectively; and 1, 2, and 3 refer to the number of .
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WEBSep 1, 2021 · Only by superimposing the two values can the real dissipated energy of coal be obtained. In the process of unloading and loading confining pressure, the axial dissipated energy can be expressed as: (13) U d 1 = W 1 − E e 1 = σ 1 ′ ∫ d ε 1 − − ∫ d ε 1 + where ε 1 − and ε 1 + are the axial strain values in the confining ...
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WEBMar 12, 2023 · The load–unload tests of coalrock combination were carried out in this study, and the specific setting is as follows: Scheme I conventional triaxial compression test. ... In addition, in the process of unloading confining pressure, the axial strain of the sample changes little before failure, and it starts to increase significantly when ...
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