Monitoring strata behavior due to multi-slicing top coal caving longwall mining in steeply dipping extra thick coal seam

Dong-feng, Yun; Li, Zhu; Cheng, Wendong; Fan, Zhendong; Wang, Dongfang; Yuan-hao, Zhang

doi:10.1016/j.ijmst.2016.11.002

Cited by 38 publications

(32 citation statements)

References 2 publications

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“…e top coal is easily broken under the influence of supporting pressure. At the same time, the more dense the fissures are, the more easily the top coal is broken, and the smaller the degree of eruption is, the more favorable it is to release, that is, the better the release of top coal, and vice versa [33][34][35]. In addition, the top coal caving is also related to the period of the roof, the depth of the coal seam, the hardness of the coal seam, the amount of sand, and the filling factor.…”

Section: Introductionmentioning

confidence: 99%

Study on Roof‐Coal Caving Characteristics with Complicated Structure by Fully Mechanized Caving Mining

Wang

et al. 2019

Shock and Vibration

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With mining technology and mechanization degree being improving, fully mechanized caving mining technology (FCM) has become a main method for thick coal seam extraction in China. However, roof-coal caving characteristics in turn restrict its recovery efficiency, especially for the coal seam with complicated structure (CCS), that is, the coal seam comprises hard or soft coal and gangue. In order to explore the key factors influencing the roof-coal caving and recovery characteristics, related research work has been conducted as follows: firstly, a mechanical model of CCS has been established, which indicates the strength of the coal and gangue will directly affect the roof-coal recovery. Meanwhile, based on the geological settings of Qinyuan coal mine, numerical simulation on roof-coal caving law under different thicknesses of hard or soft coal and gangue has been performed using UDEC software. The results show that the maximum principal stress will increase with the increase of mining depth, making the roof-coal to break easily. Furthermore, the range of the plastic zone of the top coal and the damage degree of the top coal increase with the increase of mining depth. Physical modeling results show that when an extraction-caving ratio is 1, the number of times the coal arch forms is 0.43 at every caving, up to a maximum of 3; the number of times coal arch forms with an extraction-caving ratio of 2 is 4.65 times larger than that with an extraction-caving ratio of 1. The probability of coal arch formation with an extraction-caving ratio of 3 is minimal, about 0.4, which is due to that the arch span is large and the curvature is small, so it is difficult to form a stable arch structure. According to the mechanical characteristics of roof-coal in Qinyuan coal mine, deep-hole blasting technique has been used to reduce the fragments of roof-coal crushed. The results show that this technique can effectively improve the recovery of roof-coal.

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Section: Introductionmentioning

confidence: 99%

Study on Roof‐Coal Caving Characteristics with Complicated Structure by Fully Mechanized Caving Mining

Wang

et al. 2019

Shock and Vibration

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“…In recent years, with the saturation of conventional coal mine resources, increasingly, steeply dipping coal seams (SDCS) with a dip angle of 35 -55 and complex enrichment conditions are being mined (Wu et al, 2014), particularly, in China (Tu et al, 2015;Yun et al, 2017). Many scholars have carried out systematic research on the mining technology of SDCS (Bodi, 1997;Deb et al, 2017), for example, top-coal caving mining and staggered arrangement roadway layout mining were successfully applied to SDCS (Wang et al, 2017b;Wang et al, 2017c;Zhao et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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

Chi

Yang

2019

Energy Exploration & Exploitation

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Roof regeneration in coal mining occurs when the remaining bottom slice of thick coal is re-mined. In view of the challenges of roof fall and instability support of a regenerative roof in the mining of steeply dipping coal seams, combined with the geological and engineering conditions of the working face in the Panbei Coal Mine, the mechanism of the instability of the regenerative roof and support is studied, and control countermeasures are proposed. Based on the comprehensive combination of the measurement of the roof structure, physical simulation, numerical simulation, and theoretical analysis, the cementation and compaction degree of the regenerated roof were described. The caving and sliding law of the regenerated roof after bottom slice mining was explored, and the model of support dumping and sliding instability under the roof fall state was established. The results obtained yielded three main findings. Firstly, the compaction degree of the regenerative roof is higher than that of the middle part of the working face, and the compaction degree of the upper part of the working face is the smallest. Secondly, the overburden structure instability of the bottom slice underwent six stages. The fracture of the cantilever beam and the slippage of gangue are the reasons for the enhancement of the acoustic signal at each stage. Finally, the upper part of the stope was identified as the crucial zone in the prevention and control of the support instability. A moving method of metal mesh with pressure and roof scraping was developed, and the support anti-overturning and anti-skid jack was set up to effectively control the stability of the support and roof fall, for safe and efficient mining of a steeply dipping coal seam under a regenerative roof.

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“…However, it is still difficult to use gob-side entry retention for the working faces of steeply inclined coal seams because of complications. For example, in a steep coal seam, the rock beams of the lateral main roof (or the immediate roof strata) are likely to move along the inclined direction of the bedding [14][15][16]. Under such circumstances, the roadside filling body (an artificial wall created by pouring high-water quick-setting materials) is expected to bear a large shear force, which can lead to the overall slipping and bulging of the filling body [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

An Innovative Support Structure for Gob-Side Entry Retention in Steep Coal Seam Mining

Ning

Wang

et al. 2017

Minerals

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This study considered longwall working face No. 41101-located in a steeply inclined coal seam at the Awuzisu coal mine in Xinjiang, China-as an example in which macroscopic shear cracks had occurred in the cement-based filling body of the gob-side entry retention structure. A mechanical model of the support structure for the gob-side entry retention was first established. Then, field observations and laboratory tests were used to obtain the force exerted by the coal wall on the main roof, the relationship between the axial bearing capacity and compression ratio of the rubble inside the gob, the supporting force exerted by the rubble and filling body, and the thrust of the rubble on the filling body. The shear stress experienced by the roadside filling body of the gob-side entry retention in working face No. 41101 was calculated to be 15.89 MPa. To meet the needs of roadside support, an innovative roadside backfill-truss support structure was adopted, with a 60 • angle of inclination used for the anchor bolts of the gob-side entry retention structure. In this way, the ultimate shear strength was improved by 107.54% in comparison with the cement-based filling body.

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Monitoring strata behavior due to multi-slicing top coal caving longwall mining in steeply dipping extra thick coal seam

Cited by 38 publications

References 2 publications

Study on Roof‐Coal Caving Characteristics with Complicated Structure by Fully Mechanized Caving Mining

Study on Roof‐Coal Caving Characteristics with Complicated Structure by Fully Mechanized Caving Mining

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

An Innovative Support Structure for Gob-Side Entry Retention in Steep Coal Seam Mining

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