Effects of high temperature on the microstructure and mechanical behavior of hard coal

Cheng-dong, SU; Qiu, Jiadong; Wu, Qiao; Weng, Lei

doi:10.1016/j.ijmst.2020.05.021

Cited by 60 publications

(17 citation statements)

References 23 publications

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“…Fig. 7(a) indicates that after 100a, the coal seam moisture content increases from 0% to 50%, and the maximum temperature reached by the coal seam decreases from 540℃ to 280℃.Under high temperature conditions, coal will go through two stages of drying degassing and coal matrix pyrolysis (Su et al 2020), and part of the heat of magma intrusion was absorbed in the degassing process of water in coal, so the higher the moisture of coal seam, the lower the temperature after magma intrusion.…”

Section: Effect Of Water Content On Coal Seam Heat Conduction During Magma Coolingmentioning

confidence: 99%

Numerical simulation of magma intrusion on the thermal evolution of low-rank coal

et al. 2021

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To study the effect of magma intrusion on the thermal evolution of low-rank coal with high water content, the mathematical relationship between water content variation and thermal conductivity of low-rank coal was analyzed by COMSOL Multiphysics numerical simulation and field validation. Taking Daxing Mine in Tiefa coalfield as the research background, the effects of magma finite time intrusion mechanism and water volatilization in coal on thermal evolution and organic maturity of coal seam are investigated in this paper. The results show that as the sill thickness increases, the thermal evolution temperature of the coal seam increases, the required thermal evolution time increases and the final retention temperature increases after the coal seam is cooled down. Approaching the magma, the maximum temperature that the coal seam can reach increases, the maximum temperature lasts longer, and the final temperature retained by the coal seam becomes higher. The increase of water content of coal makes the thermal conductivity increase, and the rate of heat transfer from coal seam is accelerated, and more heat is transferred to distant places in the same time. At the same time, the heat lost by the magma in the same time increases, the time required for the cooling of the magma decreases, and the maximum temperature reached by the underlying coal seam is significantly lower. The presence of moisture weakens the thermal evolution of the magma to the coal seam and reduces the expected maturity of the coal. The results of average random vitrinite reflectance (R o ) and moisture examination of coal samples collected at the Daxing Mine site verified the numerical simulation results of magma thermal evolution.

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Section: Effect Of Water Content On Coal Seam Heat Conduction During Magma Coolingmentioning

confidence: 99%

Numerical simulation of magma intrusion on the thermal evolution of low-rank coal

et al. 2021

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“…In this regard, the surrounding rock adjacent to the excavation profile is actually in a nonuniform stress distribution state [5][6][7][8], making the deformation and failure of the surrounding rock extremely complicated [9][10][11][12]. Accordingly, the pseudo triaxial compression tests on the rock specimens may not be able to fully meet the demand of actual engineering [13][14][15][16]. erefore, it is necessary to investigate the deformation behaviors and mechanical properties of the rock specimen under a nonuniform stress state.…”

Section: Introductionmentioning

confidence: 99%

Unconfined and Triaxial Compression Tests on Hollowed Cylindrical Sandstones to Explore the Infilling Effects on the Deformation and Mechanical Behaviors

Liu

Xiao

Weng

et al. 2021

Advances in Materials Science and Engineering

Self Cite

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In practical engineering, the mechanical properties of the surrounding rock often reflect the bearing capacity of the support. To investigate the relations between the surrounding rock and the support, solid specimens, hollowed cylinders, and hollowed cylinders filled with two kinds of cement mortars are tested under unconfined and conventional triaxial compressions. The effects of the infilling on the stress-strain curves, deformation features, mechanical properties, and failure patterns are schematically investigated. The results show that under the triaxial compression condition, each infilled specimen exhibits obvious residual carrying capacity though a slight stress drop occurs after the peak stress. The cement mortar exerts a positive effect on the carrying capacity of the rock, and the infilling having a higher strength and stiffness contributes to a more pronounced enhancement of the overall strength of the specimens. Under the triaxial compression condition, merely a dominated shear fracture can be seen on the surfaces, and with relatively high confining pressure (σ3 = 20 and 30 MPa), both the rock and cement mortar were cut into two parts by the dominated shear fracture. The laboratory tests in this study provide a simple and feasible way of investigating the interaction of the support system with the surrounding rock.

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“…If proper treatment measures are not taken, the mud cake can become more and more dense under the action of the cutter head thrust, causing both the oil cylinder thrust and the cutter head rotating moment to increase. In addition, high temperature can occur on the surface of the cutter head due to friction [8][9][10][11], which enhances the soil adhesion, and the situation becomes even worse if water migration occurs to the soil on the excavated face [12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Experimental Research on the Impact of Interface Temperature on the Adhesion Properties of Clay under the Condition of Different Contacting Time

Qiu

Zhang

2021

Geofluids

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Mud cakes are very likely to occur at the shield cutter when the shield machine passes through a clay stratum, which adhere to the cutter and reduce the excavation efficiency. Due to the thrust of the cutter, the mud cakes are compacted and cause friction at the soil-structure interface, which results in high temperature and aggravates the adhesion, and the effect tends to become stronger as the heating process lasts. In this paper, the effects of the interface temperature and the contacting time between the soil and the hot surface on the adhesion properties of the soil were studied by a self-made adhesion test device. According to the findings, at low interfacial temperature (≤40°C), both the adhesion force and the amount of adhered soil were insignificant in a short term, and the effects were found to be strengthened as the contacting time went on; at the high interfacial temperature (≥50°C), very significant soil adhesion occurred at the structure surface within a short time, and as the contacting time increased, the amount of the adhered soil decreased rapidly while the adhesion force kept increasing, and both tended to remain a constant and become independent with the temperature after a long-term contact. This study is of guiding significance for understanding the formation and development of the shield mud cakes during shield construction.

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Effects of high temperature on the microstructure and mechanical behavior of hard coal

Cited by 60 publications

References 23 publications

Numerical simulation of magma intrusion on the thermal evolution of low-rank coal

Numerical simulation of magma intrusion on the thermal evolution of low-rank coal

Unconfined and Triaxial Compression Tests on Hollowed Cylindrical Sandstones to Explore the Infilling Effects on the Deformation and Mechanical Behaviors

Experimental Research on the Impact of Interface Temperature on the Adhesion Properties of Clay under the Condition of Different Contacting Time

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