Present situation of fully mechanized mining technology for steeply inclined coal seams in China

Tu, Hongsheng; Tu, Shihao; Yuan, Yue; Wang, Fangtian; Bai, Qingsheng

doi:10.1007/s12517-014-1546-0

Cited by 48 publications

(33 citation statements)

References 7 publications

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“…Here, the observations on the 'coal wall spalling phenomenon' were taken as representative of the 'number of blocks detached from the coal wall.' The following features of rockfall disasters in longwall workings of SDCSs are based on previous works (Tu et al 2009;Cao et al 2013;Tu et al 2015;Wu et al 2017aWu et al , 2018.…”

Section: Rockfall Characteristics In Longwall Working Of An Sdcsmentioning

confidence: 99%

“…Rockfall occurrences in open-pit mines, quarries, and slopes are well documented, and many recent examples have shown that rockfalls can also occur in underground steeply dipping coal seams (SDCSs) (Tu et al 2009;Cao et al 2013;Tu et al 2015;Wu et al 2017a). A rockfall in the longwall of an SDCS also has the colloquial name flying gangue hazard (Liu and Wu 2014;Wu et al 2017aWu et al , 2018.…”

Section: Introductionmentioning

confidence: 99%

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Risk mitigation for rockfall hazards in steeply dipping coal seam: a case study in Xinjiang, northwestern China

Wang

et al. 2021

Geomatics, Natural Hazards and Risk

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Many recent examples have shown that rockfalls can occur in underground steep coal mines. The stratigraphic circumstances, block formation mechanism, and cumulative damage effects of rockfalls in the longwalls of a steeply dipping coal seam (SDCS) make them detrimental to workplace safety. Therefore, this study examined an approach for mitigating rockfall hazards in SDCSs. A passive mesh system was installed to prevent the propagation of rockfalls, which decreased the number of collisions between the falling rocks and mining equipment. The interactions of the falling rocks and passive mesh were studied using a series of full-scale numerical impact tests. The following conclusions could be drawn. The displacement of the mesh increased with the rockfall kinetic energy, showing the characteristic of strain hardening. The peak stress appeared near the contact area between the rockfall and mesh, and it spread to the mesh edge in an X-shaped pattern. Stress concentrations were likely to occur in areas that were in direct contact with the mesh and mesh edges. The displacement of the mesh increased when the incidence angle increased, and the number of mesh cells entering the plastic state increased significantly. The internal energy ratio increased with an increase in the incidence angle, indicating that a greater incidence angle led to a larger amount of kinetic energy being transferred from the block into the internal energy of the passive mesh. Finally, the method was verified by comparing the numerical test with the on-site damaged equipment. The high replacement frequency of a passive mesh system and the annual fatality rate in the longwalls of SDCS were significantly improved. This study provided the design for a drapery mesh system for rockfall disaster prevention, particularly the mitigation of rockfall hazard risks in underground SDCSs.

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Section: Rockfall Characteristics In Longwall Working Of An Sdcsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Risk mitigation for rockfall hazards in steeply dipping coal seam: a case study in Xinjiang, northwestern China

Wang

et al. 2021

Geomatics, Natural Hazards and Risk

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“…Producing high-quality coking coal and anthracite yields considerable economic gains (Tu et al 2015;Wu et al 2020). In China, over half of the production of these rare types of coal occurs in steeply dipping coal seams (SDCSs), which make up about 20% of the proven resources (Yun et al 2017;Wang et al 2019Wang et al , 2020.…”

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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“…ey are widely distributed in major coal production areas worldwide, including the Ruhr Coalfield in Germany, the Lorraine Coalfield in France, the Karaganda Coalfield in Kazakhstan, the Donbas Coalfield in Ukraine, and the West Virginia Coalfield in the US [2]. In China (Sichuan, Xinjiang, Gansu, Chongqing, and Ningxia), SDCSs have proven reserves of up to 180 to 360 billion tons and outputs of 150 to 300 million tons, accounting for 10-20% and 5-8% of all the proven reserves and outputs in China, respectively [3][4][5]. Due to their unique sedimentary environment, over 50% of SDCSs are coking coal and anthracite coal, which are rare varieties under protective mining [6].…”

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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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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Present situation of fully mechanized mining technology for steeply inclined coal seams in China

Cited by 48 publications

References 7 publications

Risk mitigation for rockfall hazards in steeply dipping coal seam: a case study in Xinjiang, northwestern China

Risk mitigation for rockfall hazards in steeply dipping coal seam: a case study in Xinjiang, northwestern China

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

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

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