Coalfield structure and structural controls on coal in China

Cao, Daiyong; Wang, Anmin; Ning, Shuzheng; Li, Huantong; Guo, Aijun; Kang, Lan; Tan, Jie; Zheng, Zhihong

doi:10.1007/s40789-020-00326-z

Cited by 25 publications

(20 citation statements)

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“…Energies 2020, 13, x FOR PEER REVIEW 7 of 21 3. DOC = A (900-700 cm −1 )/A (1600 cm −1 ), representing the polycondensation degree of the aromatic rings; 4.…”

Section: Nanoindentation Experiments Resultsmentioning

confidence: 99%

“…The Fengfeng coal mine area is located in Taihangshan fault zone [3], North China, belonging to northern China coal occurrence area (Figure 1). The coal-bearing strata in the Fengfeng mining area is the Late Paleozoic Carboniferous-Permian with the No.…”

Section: Geological Backgroundmentioning

confidence: 99%

“…The physical and chemical properties of tectonically deformed coal (TDC) are significantly different from those of unaltered coal [1]. Coal basins in China have generally experienced intensive tectonic movements [2,3]; therefore, TDCs are widespread, hindering the safe and effective exploitation of coal resources and coalbed methane [4][5][6][7]. Therefore, TDC has been studied extensively [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Macromolecular Structure Controlling Micro Mechanical Properties of Vitrinite and Inertinite in Tectonically Deformed Coals—A Case Study in Fengfeng Coal Mine of Taihangshan Fault Zone (North China)

et al. 2020

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In order to study the evolution of the mechanical properties and macromolecular structures in different macerals of tectonically deformed coal (TDC), vitrinite and inertinite samples were handpicked from six block TDCs in the same coal seam with an increasing deformation degree (unaltered, cataclastic, porphyroclast, scaly and powdery coal). The micro mechanical properties were tested by the nanoindentation experiment and the macromolecular structures were measured using 13C nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). The results show that the range of hardness and elastic modulus of inertinite is 0.373–1.517 GPa and 4.339–12.158 GPa, respectively, which is significantly higher than that of vitrinite with values of 0.278–0.456 GPa and 4.857–7.810 GPa, respectively. From unaltered coal to powdery coal, the hardness of vitrinite and inertinite gradually decreases, with the difference between these macerals becomes smaller and the elastic modulus of vitrinite shows an increasing trend, while that of inertinite was more variable. Both the NMR and FITR results reveal that the macromolecular structure of inertinite has similar structural transitions as vitrinite. As the degree of deformation increases, the aliphatic side chains become shorter and the aromaticity is increasing. Macromolecular alterations caused by tectonic stress is expected to produce defects in the TDCs, therefore there should be more interspacing among the macromolecular groups for the extrusion of macromolecules caused by the indenter of the nanoindentation experiment, thereby reducing the hardness. The elastic modulus of coal is believed to be related to intermolecular forces, which are positively correlated to the dipole moment. By calculating the dipole moments of the typical aromatic molecular structures with aliphatic side chains, the detachment of the aliphatic side chains and the growth of benzene rings can both increase the dipole moment, which can promote elastic modulus. In addition, the increasing number of benzene rings can create more π-π bonds between the molecules, which can lead to an increase in the intermolecular forces, further increasing the elastic modulus.

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“…Energies 2020, 13, x FOR PEER REVIEW 7 of 21 3. DOC = A (900-700 cm −1 )/A (1600 cm −1 ), representing the polycondensation degree of the aromatic rings; 4.…”

Section: Nanoindentation Experiments Resultsmentioning

confidence: 99%

Section: Geological Backgroundmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Macromolecular Structure Controlling Micro Mechanical Properties of Vitrinite and Inertinite in Tectonically Deformed Coals—A Case Study in Fengfeng Coal Mine of Taihangshan Fault Zone (North China)

et al. 2020

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“…e lower seams' mining causes upper seam movements and ground stress unloading, which introduce fractures influencing the stability of surrounding rock of upper seam [8][9][10][11][12][13][14][15]. e research of the upward mining method mainly focuses on the overburden damage analysis caused by lower seam mining and the deformation monitoring and strata control technology while upper seam mining.…”

Section: Introductionmentioning

confidence: 99%

Analysis and Monitoring Technology of Upper Seam Mining in Multiunderlayer Goaf

Hang

Cao

2021

Advances in Civil Engineering

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Based on the background of close coal seam mining in the Qianjiaying coal mine, Tangshan, China, the feasibility of the upper seam mining in complex underlaying goaf is analysed using the roof caving analysis and numerical method. The deformation of the mining seam and roadways is monitored and analysed by field measurement and 3D laser scanning. The deformation characteristics of #5 seam after mining 1378P, 2071P, 2072P, and 2091P working panels with a depth of 39–54 m below the #5 seam are analysed using roof caving analysis and numerical method. Results show that the maximum deformation of #5 seam in the superimposed area of the lower goafs reaches 2.5 m and the maximum deformation in the single coal goaf is 1.5 m. The maximum seam inclination is 1.9°. The subsidence of the floor of 1359P roadways is obtained by field measurement, and the result is consistent with numerical calculation. ZEB-HORIZON 3D laser scanner was used to measure and model the roadway deformation. Based on the analysis of multiple scanning data, the deformation of the 1359P roadways was obtained. Results show that the deformation of the surrounding rock of the roadway is not great, the maximum displacement of the roof fall is 30 mm, and the maximum rib convergence is 25 mm. It can be concluded that the #5 seam can be recovered in this complex underlying lower seams’ mining condition.

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“…Rockbolts have been used to provide ground support in mines for more than one century [1][2][3][4][5]. Rockbolts are characterized by highly effective reinforcement and simple Appl.…”

Section: Introductionmentioning

confidence: 99%

An Equivalent Radial Stiffness Method of Laboratory SEPT on Anchorage Performance Prediction of Rockbolts under Different Field Geoconditions

Zhang

Han

et al. 2021

Applied Sciences

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The short encapsulation pull-out test (SEPT) is extensively used in rockbolting research or engineering. The field SEPT is time-consuming and labor-intensive, and its result is only applicable to the tested in situ. The laboratory SEPT is usually employed in theoretical rockbolting research due to its easily controlled variables. However, the design of laboratory SEPT is quite different, as there is no standard testing method, resulting in the applicability and limitations of each study not being clear. Accordingly, the aim of this paper is to bridge the gap between laboratory SEPT research and field application. On the basis of thick-walled cylinder theory, a mechanical model of a rock bolt subjected to axial load was established under consideration of the deformational behavior of confining materials around the bolt. Plane stress analysis was introduced to derive the analytical relationship between the axial force of the bolt and the deformation of the confining materials. A new approach of laboratory SEPT sample design was established, namely, equivalent radial stiffness theory, to simulate anchorage performance in a specific in-situ geocondition. Consequently, the field SETP could be replaced by laboratory testing using properly designed bolting samples with a certain level of accuracy. In addition, the application scope of previous laboratory SEPT research could be accurately defined. Laboratory SEPT was carried out to study the anchoring performance of right spiral rebar bolts under different confining materials. Poly Vinyl Chloride (PVC) tubes with a thickness of 31 mm, #60 aluminum (Al) tubes with a thickness of 5.8 mm, and #20 steel tubes with a thickness of 5.5, 7.0 mm were used in sample preparation to simulate soft, medium, and hard surrounding rocks in the field. The anchorage performance of the bolt under different geoconditions was systematically proposed, which provides a technical approach for similar research using different anchoring materials. A negative exponential expression formulating the axial load capacity of the right spiral bolts for the full spectrum of the surrounding rocks’ strength was derived on the basis of theoretical analysis and data regression. It can be used for preliminary reinforcement design, as well as the accurate key parameter setting in the numerical calculation of roadway deformation using right spiral bolts. The theoretical prediction is highly consistent with the testing results in the literature, which confirms the validity and reliability of this research. This study contributes to the establishment of a laboratory SEPT standard in rock mechanics.

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Coalfield structure and structural controls on coal in China

Cited by 25 publications

References 1 publication

Macromolecular Structure Controlling Micro Mechanical Properties of Vitrinite and Inertinite in Tectonically Deformed Coals—A Case Study in Fengfeng Coal Mine of Taihangshan Fault Zone (North China)

Macromolecular Structure Controlling Micro Mechanical Properties of Vitrinite and Inertinite in Tectonically Deformed Coals—A Case Study in Fengfeng Coal Mine of Taihangshan Fault Zone (North China)

Analysis and Monitoring Technology of Upper Seam Mining in Multiunderlayer Goaf

An Equivalent Radial Stiffness Method of Laboratory SEPT on Anchorage Performance Prediction of Rockbolts under Different Field Geoconditions

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