Experimental Study on Damage and Gas Migration Characteristics of Gas-Bearing Coal with Different Pore Structures under Sorption-Sudden Unloading of Methane

Wang, Gang; Guo, Yangyang; Du, Changang; Sun, Lulu; Liu, Zhiyuan; Wang, Yue; Cao, Jianjun

doi:10.1155/2019/7287438

Cited by 11 publications

(8 citation statements)

References 28 publications

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“…e effect of adsorbed state gas on the coal sample is more obvious, which can reduce the surface free energy of coal matrix and the cementation force between coal particles. is will make it easier to produce microfracture by the action of expansion stress and thus expands the wedge-opening effect of free-state gas on coal pore and fissure [28,29]. It can be found from Figure 6 that the lateral and axial strains of coal samples in the process of gas adsorption significantly increased, and the early strain rate of coal samples is relatively high, but the increase rate of strain decreases with the increase of adsorption time, and the greater the pressure, the greater the strain at adsorption saturation.…”

Section: Dilatancy Effect Of Filling Gas and Adsorbing Gas On Coalmentioning

confidence: 99%

Effect of Gas on Burst Proneness and Energy Dissipation of Loaded Coal: An Experimental Study Using a Novel Gas‐Solid Coupling Loading Apparatus

Wang

et al. 2021

Shock and Vibration

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Deep coal mining is seriously affected by a combined dynamic disaster of rock burst and coal and gas outburst, but the influence mechanism of gas on this combined dynamic disaster is still not very clear, which is significantly different from the single type disasters. In this study, to explore the effect of gas on the coal-rock burst, a novel gas-solid coupling loading apparatus is designed to realize gas adsorption of coal sample with burst proneness and provide uniaxial loading environment under different gas pressure. A series of uniaxial compression tests of gas-containing coal with different gas pressure is carried out, and the energy dissipation process is monitored by an acoustic emission (AE) system. Results show that the macroscopic volume strain of the coal sample increases as gas adsorption and gas pressure increase under constant uniaxial loading pressure. Gas has the ability to expand the pores and natural fractures in coal sample by mechanical and physicochemical effects, which leads to a degradation in microstructure integrity of coal sample. With the increase of gas pressure, both the macrouniaxial compression strength (UCS) and elastic modulus show a downward trend; the UCS and elastic modulus of coal samples with 2 MPa gas pressure reduce by 58.78% and 48.82%, respectively, compared to those of the original coal samples. The main reason is that gas changes the pore-fissure structure and the mesoscopic stress environment inside the coal sample. Owing to the gas, the accumulated elastic energy of the gas-containing coal samples before failure reduces significantly, whereas the energy dissipated during loading increases, and the energy release process in the postpeak stage is smoother, indicating the participation of gas weakens the burst proneness of the coal sample. This study is of important scientific value for revealing the mechanism of combined dynamic disaster and the critical occurrence conditions of coal-rock burst and coal and gas outburst.

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Section: Dilatancy Effect Of Filling Gas and Adsorbing Gas On Coalmentioning

confidence: 99%

Effect of Gas on Burst Proneness and Energy Dissipation of Loaded Coal: An Experimental Study Using a Novel Gas‐Solid Coupling Loading Apparatus

Wang

et al. 2021

Shock and Vibration

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“…Moreover, it could destroy underground facilities and lead to casualties. When it is serious, it can cause gas explosion and coal dust explosion, leading to larger-scale damage (Lama and Bodziony, 1998;Liu and Harpalani, 2013;Guo et al, 2020;Sheng and Derek, 2016;Wang et al, 2013Wang and Guo, 2019). In recent years, with the increase of coal mining depth in China, the outburst risk of coal seams is increasing.…”

Section: Introductionmentioning

confidence: 99%

EDEM-FLUENT coupled simulation of coal-gas outburst two-phase flow

Guo

Wang

et al. 2021

Energy Exploration & Exploitation

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In the process of coal-gas outburst, the gas-solid two-phase flow of pulverized coal and gas will induce large-scale damage to underground mining. In this work, in order to study the dynamic evolution law of gas-solid two-phase flow of coal-gas outburst, and clarify the short-time destructive effect of outburst dynamic phenomenon, an EDEM-FLUENT coupled model is constructed to realize the numerical simulation of coal-gas outburst two-phase flow. The simulation results show that the flow velocity of pulverized coal in a short time (tens of milliseconds) approaches to the maximum velocity rapidly, which can reach 60 m/s. The velocity of pulverized coal is inversely proportional to the particle size. The initial acceleration of particles is slow, and then the acceleration increases rapidly. The accumulation angle of pulverized coal in the outburst hole is about 21° and is far less than the natural accumulation angle of pulverized coal, which is consistent with the general phenomenon of coal-gas outbursts. The results also show that the shock wave overpressure of the coal-gas outburst of numerical simulation is similar to that of the physical simulation test, and the difference is less than 10%. And the pressure change in the roadway is completed in short time. In terms of spatial relationships, the pressure at the position closest to the outburst mouth is not the maximum, and the maximum pressure exists at a certain position away from the outburst mouth.

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“…The mining-induced fractures propagate gradually from the gob area to the ground surface and induce surface subsidence and corresponding environmental damage [7,8]. Meanwhile, these fractures are the flow paths of geofluids, such as methane [9], water [10,11], and slurry [12][13][14]; corresponding surface subsidence can be reduced by filling these fractures during mining. Grout injection into the overburden bedding fractures is one such method and is used to control mining subsidence [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of Slurry Flow in Mining-Induced Fractures during Longwall Overburden Grout Injection

Xuan

Zheng

et al. 2020

Geofluids

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Slurry flow in mining-induced overburden fractures is an important theoretical concept for the grouting design of longwall overburden grout injection engineering. In this study, a visual experimental simulation system of longwall overburden grouting was designed to study the flow, pressure distribution, consolidation, and fill thickness of fly ash slurry in overburden bedding separation. Experiments showed that the slurry generates a radial and bidirectional flow during nonpressure grouting and presents itself as an approximately elliptical dominant flow channel under pressure injection. This channel expanded horizontally along the strike direction and gradually became tabular. The slurry pressure increased as the grouting time increased. Although the pressure curves at different locations exhibited similar trends, their values did not decrease as the distance from the borehole center decreased during observations. Bleeding and consolidation occurred in the slurry as soon as it flowed out of the borehole to the fracture, and the degree of consolidation increased as a function of the distance from the injection borehole. The bleeding water gathered continually to the boundary of the bedding separation fracture and was then seeped to and stored by the underlying strata based on the injection pressure. The final injection fill is manifested as a half pace with a large thickness at the center. This research provides a theoretical basis for the design and optimization of overburden grout injection in underground longwall mining.

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Experimental Study on Damage and Gas Migration Characteristics of Gas-Bearing Coal with Different Pore Structures under Sorption-Sudden Unloading of Methane

Cited by 11 publications

References 28 publications

Effect of Gas on Burst Proneness and Energy Dissipation of Loaded Coal: An Experimental Study Using a Novel Gas‐Solid Coupling Loading Apparatus

Effect of Gas on Burst Proneness and Energy Dissipation of Loaded Coal: An Experimental Study Using a Novel Gas‐Solid Coupling Loading Apparatus

EDEM-FLUENT coupled simulation of coal-gas outburst two-phase flow

Experimental Study of Slurry Flow in Mining-Induced Fractures during Longwall Overburden Grout Injection

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