Analysis of regenerated roof and instability support control countermeasures in a steeply dipping working face

Chi, Xiaolou; Yang, Ke; Fu, Qiang

doi:10.1177/0144598719897422

Cited by 12 publications

(7 citation statements)

References 12 publications

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“…ey reported the temporal sequence and asymmetry in the dip direction, as well as their variations in different parts of the strike [22]. Our field monitoring data demonstrated that due to the influence of the dip angle, the distance between the caving gangue and support gradually increased from the bottom to the top along the working face [11]. is implies that the mined-out area is under a nonuniform filling state along the working face dip due to a steep dip angle since a nonzero angle β is formed by the floor/support and caving gangue/floor contact lines.…”

Section: Variation In the Support Load Bearing Characteristics Induced By The Spalling -Roof Collapse Hazard Chainmentioning

confidence: 73%

“…Since the recycling rate of the top-coal caving mining technique is quite low, the fully mechanized longwall mining of soft coal faces with large cutting heights has become a conventional technique for improving the high-efficiency recovery in thick SDCSs [11]. As the cutting height continues to rise, the stress concentration in the surrounding rock in the mined-out area gradually increases, the stress release space enlarges, and the magnitude and intensity of the surrounding rock movement grow [12].…”

Section: Introductionmentioning

confidence: 99%

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Mechanism and Integrated Control of “Rib Spalling: Roof Collapse—Support Instability” Hazard Chains in Steeply Dipping Soft Coal Seams

Liu

Yang

Tang

2021

Advances in Materials Science and Engineering

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The hazard chain of rib spalling, roof collapse, and support instability occurring in steeply dipping coal seams (SDCSs) significantly threatens the safety and productivity of underground mining. A three-dimensional coal wall model was established considering the damage to the coal wall from the abutment pressure based on the new concept of the main control weak surface (MCWS) defined by the authors. Then, a support mechanical model under the conditions of a dynamic load induced by a sliding roof was constructed. Integrated control measurements based on the models above were developed and taken for the dangerous area of hazard chains in working faces. The results indicated that the dimensions of rib spalling were dominated by the shape, dimensions, and friction angle of the coal wall element. In detail, the order of the importance of the element failure factors, based on their sensitivities, was the roof load (6.33), the dip of the panel (−5.03), the friction angle of the coal (−3.24), the cohesion of the coal (−3.02), and the sidewall protecting force (−0.087). Additionally, the order of importance of the frictional sliding factors of the slip body was the MCWS cohesion (−0.293), roof load (0.213), and MCWS friction angle (−0.079). Equations for the threshold forces between supports under the support dumping and sliding limit states were obtained; the knowledge of these forces ensured support stability under a sliding roof. The support work resistance varied synchronously in different parts of the working face and remained within 2200–4000 kN, indicating that the proposed models and control measurements considered instrumental in hazard chain control in SDCSs were reliable.

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Section: Variation In the Support Load Bearing Characteristics Induced By The Spalling -Roof Collapse Hazard Chainmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Mechanism and Integrated Control of “Rib Spalling: Roof Collapse—Support Instability” Hazard Chains in Steeply Dipping Soft Coal Seams

Liu

Yang

Tang

2021

Advances in Materials Science and Engineering

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“…In the process of longwall caving mining in the SDCS, the roof movement, deformation, and failure characteristics are active in the middle and upper area along the inclined direction of the working face. The contact and loading characteristics of the roof and support in this area are complex, making the stability control of the "support surrounding rock" system more complicated and easy to cause safety accidents (Wu et al, 2014; Xie et al, 2018; Chi et al, 2020; Wu et al, 2021; Hu et al, 2021). The local filling mining technology of the SDCS longwall mining effectively bears the stress of surrounding rock, reduces the stress concentration, and influences the surrounding rock's range.…”

Section: Introductionmentioning

confidence: 99%

Compression characteristics of local filling gangue in Steeply Dipping Coal Seam

Guo

et al. 2022

Energy Exploration & Exploitation

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Coal gangue is widely used as a filling material in coal seam mining. During the gangue filling in steeply dipping coal seam, the loading rate, gangue gradation, and filling speed have an important impact on the deformation and failure of gangue, and further affect the bearing of gangue on overlying strata and the control of surrounding rock movement and deformation. Therefore, this article uses a self-made steel cylinder to conduct a gangue compression test on the HCT pressure testing machine. The research analyzes the influence of loading rate, gangue gradation, and filling rate on the deformation law of gangue in the compression process. After completing the test, the gangues with different particle size groups were rescreened, weighed, and recorded to analyze the crushing situation in the compression process. The results show that loading rate, gangue gradation, and filling speed have greatly influenced filling gangue's bearing capacity, deformation, and crushing rate. The larger the loading rate of gangue, the greater the bearing capacity and deformation of gangue, and the higher the crushing rate of gangue. The smaller the gangue gradation, the smaller the deformation, and the stronger the resistance to deformation. A more optimized gangue gradation ratio is obtained according to the distribution law of the mass proportion of gangue with different particle size groups after compression. The faster the filling speed of manual filling gangue, the greater the strength and deformation of the gangue body. Moreover, the faster filling speed can effectively improve when the strength reaches the peak and deformation tend to be stable. The results can provide theoretical guidance for the local filling of artificial gangue in the longwall working face of steeply dipping coal seam.

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“…A finding regarding the distribution of mine pressure is asymmetric weighting along the dip direction of the working face during SDCS excavation (Yin et al 2010;Deng and Wang 2014;Yang et al 2015a, b;Chi et al 2020). Using the relationship between hydraulic support and surrounding rock, some researchers developed a mechanical model of the instability of support along the dip direction of the working face under different working states (Wu and Yun 1999;Wang and Jiao 2016;Yang et al 2018;Hu et al 2018;Chi et al 2019). Given that the breaking and migration features of the overlying strata are yet to be revealed accurately because of the undefined breaking process and the complexity of the SDCS mechanical features, the research progress in this direction can be reduced to the following achievements.…”

Section: Introductionmentioning

confidence: 99%

Breaking and mining-induced stress evolution of overlying strata in the working face of a steeply dipping coal seam

Chi

Yang

Wei

2021

Int J Coal Sci Technol

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The breaking features and stress distribution of overlying strata in a steeply dipping coal seam (SDCS) differ significantly from those in a near-horizontal one. In this study, the laws governing the evolution of vertical stress release and shear stress concentration in the overlying strata of coal seams with different dip angles are derived via numerical simulation, rock mechanics tests, acoustic emissions, and field measurements. Thus, the stress-driven dynamic evolution of the overlying strata structure, in which a shear stress arch forms, is determined. Upon breaking the lower part of the overlying strata, the shear stress transfers rapidly to the upper part of the working face. The damaged zone of the overlying strata migrates upward along the dip direction of the working face. The gangue in the lower part of the working face is compacted, leading to an increase in vertical stress. As the dip angle of the coal seam increases, the overlying strata fail suddenly under the action of shear stresses. Finally, the behavioral response of the overlying strata driven by shear stresses in the longwall working face of an SDCS is identified and analyzed in detail. The present research findings reveal the laws governing the behavior of mine pressure in the working face of an SDCS, which in turn can be used to establish the respective on-site guidance.

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Analysis of regenerated roof and instability support control countermeasures in a steeply dipping working face

Cited by 12 publications

References 12 publications

Mechanism and Integrated Control of “Rib Spalling: Roof Collapse—Support Instability” Hazard Chains in Steeply Dipping Soft Coal Seams

Mechanism and Integrated Control of “Rib Spalling: Roof Collapse—Support Instability” Hazard Chains in Steeply Dipping Soft Coal Seams

Compression characteristics of local filling gangue in Steeply Dipping Coal Seam

Breaking and mining-induced stress evolution of overlying strata in the working face of a steeply dipping coal seam

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