Characteristics and contributing factors of major coal bursts in longwall mines

Zhao, Wang; Qin, Changkun; Xiao, Zi‐Yi; Chen, Weizhong

doi:10.1002/ese3.1102

Cited by 8 publications

(2 citation statements)

References 26 publications

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“…Some sites of these interfaces represent thin interburdens of carbonaceous rocks or high-ash clayey coals [29,30] with low deformation characteristics and strength properties (for example, cohesion of 0.005-0.2 MPa [31,32]). When the mining front approaches such sites, the stresses change abruptly and the dynamic events take place [27,33,34]. Early detection of such weak zones will enable preventive measures to be undertaken [35] to reduce the risk of the undesirable geodynamic phenomena.…”

Section: Introductionmentioning

confidence: 99%

Method for weak zones location at the coal-bed – host rock joint relative to the problem of sudden outbursts: theory and laboratory experiment

Nazarov

2022

Frattura Ed Integrità Strutturale

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Within the framework of a geomechanical model that describes the deformation of a rock mass during the subhorizontal coal-bed extraction, the mechanism for the formation and implementation of a sudden outburst is substantiated: as working face gets close to the weak zone of coal-bed – host rock joint, areas of tensile stresses arise, which creates the prerequisites for face space spalling and coal loss with methane. The inverse problem of determining the conditions at the horizontal boundaries of a coal-bed is formulated and solved using tomography data (longitudinal wave velocity V distribution) and the empirical dependence of V on the mean normal stress σ. Lab tests results on stepwise compression of parallelepipeds made of artificial geomaterials are presented. Tomography of the specimens was performed by acoustic sounding data, and the distribution of velocities V* was found. Using the pre-established empirical dependence V(σ) for geomaterial, the distribution σ*=V-1(V*) in the specimen was calculated, which served as input data for inverse problem of determining the shear stresses σxy at the “specimen faces – press platens” joints. Lab data inversion confirmed the possibility of identifying weak zones of the boundaries where σxy=0. These zones are associated with probable nucleus of failure and sudden outbursts.

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Section: Introductionmentioning

confidence: 99%

Method for weak zones location at the coal-bed – host rock joint relative to the problem of sudden outbursts: theory and laboratory experiment

Nazarov

2022

Frattura Ed Integrità Strutturale

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“…It was concluded that the maximum stress decreased with increasing temperature, and it increased with an increasing strain rate. These people established the constitutive models required for quantitative analysis based on experimental samples, but these have rarely been combined with CT experiments [9,[12][13][14][15][23][24][25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Subarea Description and Breakage Constitutive Model of Rock Mass Based on CT Test

et al. 2022

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Based on CT experiments of the mechanical behavior of a certain sandstone, the safety zone, the damaging zone, and the fracture zone of geotechnical materials were defined, and the CT threshold standard of this zone was discussed and empirically selected. Mathematical morphological image measurement technology was used to analyze the CT information of each section, and the variation law of the sandstone CT number with the loading process and the conditions of the damaging zone was studied. According to the statistical results of the CT number of the safety zone, the damaging zone, and the fracture zone obtained at each loading stage, a statistical-damage variable based on the CT number was defined, and the equation of the damage evolution pertinent to this damage variable was established. On the basis of all these data, a constitutive model that can reflect the divisional damage-fracture of sandstone was constructed. The theoretical stress–strain curve and the measured curve were well fitted, demonstrating that the improved constitutive model could accurately reflect the failure of sandstone partitions. A qualitative analysis of CT scans and a quantitative analysis of the constitutive model were combined in this experiment, which has a certain reference value for the development of geotechnical engineering experiments.

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Investigating Effects of Reverse Osmosis-Treated Water on the Corrosion Rate of Chains in Armoured Face Conveyor for Longwall Mining

Sul,

Probyn,

Donnelly

et al. 2023

Mining, Metallurgy & Exploration

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Premature failure of armoured face conveyor (AFC) chains due to corrosion is a significant proportion of the unplanned downtime experienced on longwall equipment. The AFC chains are constantly in contact with water and wet coal. The premature failure issue of AFC chains has become more prominent since the introduction of longwall top-coal caving with its additional AFC. Reverse osmosis (RO) is a popular water treatment method for reducing salinity and dissolved solids, but its impact on the corrosion of the AFC chains is unclear. This study has been commissioned to investigate the direct effects of RO water on the corrosion of AFC chains. An immersion test was carried out using AFC chain steel submerged in two water samples: untreated dam water and treated water from an RO treatment plant. Elemental analysis was conducted for both water samples, and four corrosion indices were measured for both water samples. The RO water more vigorously dissolves calcium carbonate scales leading to increased corrosion of the AFC chains although the dam water has much higher levels of calcium, chloride, sulphate, sodium, and magnesium. Bicarbonate ions are the main alkaline factor of water that provides the buffering capacity to acids. Decreased alkalinity without balancing other ions in water causes high corrosivity and decreased scaling tendencies.

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Characteristics and contributing factors of major coal bursts in longwall mines

Cited by 8 publications

References 26 publications

Method for weak zones location at the coal-bed – host rock joint relative to the problem of sudden outbursts: theory and laboratory experiment

Method for weak zones location at the coal-bed – host rock joint relative to the problem of sudden outbursts: theory and laboratory experiment

Subarea Description and Breakage Constitutive Model of Rock Mass Based on CT Test

Investigating Effects of Reverse Osmosis-Treated Water on the Corrosion Rate of Chains in Armoured Face Conveyor for Longwall Mining

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