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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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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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 1, 2024 · In the process of coal seam mining, the coal is disturbed by periodic pressure. This disturbance can be simplified to the loading process under different stress environments [5], [9], [10], [45], and the characteristics of the mining stress path are different under different advancing speeds [46]. Fig. 3 shows the loading path of the .
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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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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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WEBNov 12, 2020 · Stressstrain curves of coal from unloading tests under different confining pressures As shown in Fig. 5, the recovery of deformation and permeability occurs in the coal sample with the unloading ...
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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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WEBSep 19, 2023 · This paper presents two experimental schemes, graded cyclic loading and unloading, and variable lower limit cyclic loading and unloading, to investigate the energy evolution and acoustic emission characteristics of rocks under different cyclic loading and unloading paths. The experiments were conducted using a WAW300B microcomputer .
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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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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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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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WEBDec 15, 2023 · A novel permeability model under triaxial pressure loading–unloading was developed. • The influence of effective stress and adsorption/desorption is considered in model. • The model is verified using test results of coal seepage under three conditions. • Triaxial pressure loading–unloading has a significant effect on coal permeability.
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WEBThe hulls of tankers (as described above; see Types of ships: Tankers) are subdivided into a number of cells, or tanks, into which the liquid cargo is pumped through hoses by pumps mounted on the shore. Unloading is effected in the reverse manner by pumps mounted within the ship. Usually the only external cargohandling gear is a pair of cranes ...
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WEBMar 7, 2021 · In coal mining activities, the abutment stress of the coal has to undergo cyclic loading and unloading, affecting the strength and seepage characteristics of coal; additionally, it can cause ...
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WEBSep 1, 2017 · From the perspective of mechanics, coal mining is a loading and unloading process. The typical underground loading and unloading features are mainly distributed on the front side and the protective layer. These loions are often in a complex stress environment. The main variation of the force is shown in Fig. 1. It shows that the force ...
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WEBIn actual mining situations, the advancing speed of the working face is usually accelerated, which may affect the failure and seepage characteristics of gasbearing coal, and may even induce dynamic disasters. In order to discover the effects of such accelerated advancement of the working face, an experimental study on the failure and seepage .
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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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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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WEBOct 23, 2023 · 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. .
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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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WEBMar 29, 2024 · Conventional triaxial loading and unloading test scheme. A substantial amount of research indies that the stress distribution in the overlying strata in front of the coal face can be divided ...
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