Longwall Face Stability Index for Estimation of Chock-Shield Pressure and Face Convergence

Verma, Abhay Kumar; Deb, D.

doi:10.1007/s10706-010-9303-y

Cited by 15 publications

(7 citation statements)

References 8 publications

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“…Yun et al [17] clearly showed that the front leg pressure was greater than the rear leg pressure in another China longwall face (Figure 8a). The difference between front leg and rear leg pressures was also seen in India's longwall panels, as reported by Verma and Deb [18] (Figure 8b) and Singh and Singh [19]. During the time of monitoring, coal face was, in general, stable.…”

Section: Resultssupporting

confidence: 73%

Field Investigation of Face Spall in Moderate Strength Coal Seam at Vang Danh Coal Mine, Vietnam

Quang

2021

EES

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Face spall in moderate strength coal seam occurs less frequently but can be more severe and takes a longer time to remedy compared to face spall in the weak coal seam. This paper presents a field investigation of face spall in moderate strength coal seam at Face I-8-1, Vang Danh coal mine, Quang Ninh coal field, Vietnam. The leg pressure of shield support and face condition were monitored within two months, and on-site remedial measures to the spall were discussed. The monitoring results confirmed that the front and rear leg pressure profiles are consistent with world-wide observations. The coal face condition in actual operation was found to be more stable than that in project design. The face spall occurred along face dip direction, but mostly in small extent of less than 0.5 m deep and during transitional time between working shifts. Proper ground control near gate ends by using higher capacity shield supports and supplemental hydraulic props was identified to improve face stability in the area. On-site remedial measures proved their efficiency in small to moderate face spall extent. For main roof rupture-associated face spall, technical measures have been applied but they need further investigation to clarify their effectiveness. The paper’s results can be consulted to improve longwall face stability control in similar coal seam conditions.

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Section: Resultssupporting

confidence: 73%

Field Investigation of Face Spall in Moderate Strength Coal Seam at Vang Danh Coal Mine, Vietnam

Quang

2021

EES

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“…Based on the above-mentioned theories, a series of studies on the interaction mechanism between hydraulic support and the roof strata has been performed. A. K. Verma and D. Deb [24,25] developed an index considering the wide variations of geomining parameters to ascertain the chock shield pressure and face convergence. They found that the mechanical parameters of the main roof and coal seam were closely related to the load on the front leg of the chock-shield support.…”

Section: Introductionmentioning

confidence: 99%

Roof Strata Behavior and Support Resistance Determination for Ultra-Thick Longwall Top Coal Caving Panel: A Case Study of the Tashan Coal Mine

et al. 2018

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The Longwall Top Coal Caving (LTCC) method has greatly improved the production of ultra-thick underground coal resources. However, face fall and support closure have been becoming highly frequent accidents at the working face, and seriously threaten the safety of miners. The key to avoiding these problems is to reveal the structural evolution of the roof strata and then choose a reasonable working resistance for the hydraulic supports. According to physical modeling, theoretical analysis and field observation of the LTCC panel, four kinds of structural models can be found and defined, in consideration of the coincident movement of key strata (KS) and the mining activities of upper face in overburden strata. The KS are performed as cantilever structures, hinged structures and voussoir beam structures at three different positions in roof strata. The structural characteristics of the KS and its movement laws are shown in the four structural modes. The loads acting on the support in the four typical structural models are also analyzed. The structural instability of the broken roof strata on the upper caving panel caused by the lower ultra-thick coal seam mining is considered to be the main reason for its face's falls and support failures. Consequently, a method is proposed for calculating the working resistance of the support in the LTCC face, which is verified by the mining pressure monitoring in practice.

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“…The calculation models of the working resistance of the support under different movement types were established in succession, and the onsite measurement data were verified. Verma and Deb [13,14] modified the load estimation method according to the structural characteristics of overlying strata of a working face under hard roof conditions and acquired the computation method for the working resistance of hydraulic supports on a fully mechanized caving face for a thick coal seam under hard roof condition. The hanging arch length of the key strata on the roof and the influence factors of its caving and fracturing were obtained by combining the theoretical analyses of the cantilever beam.…”

Section: State Of the Artmentioning

confidence: 99%

“…According to the theory of mechanics of materials, the moment acted by the hard rock strata on the lower rock strata within the scope of the roof control zone in Eq. (12) can be expressed as (13) Eq. (13) is then substituted with Eq.…”

Section: Support-surrounding Rock Relation Under Movement Instabilitymentioning

confidence: 99%

Influence Characteristics of Double-Stratum Hard Roof Movement in a Fully Mechanized Top Coal Caving on the Working Resistance of Supports

Shi¹,

Yin²,

Li³

et al. 2020

JESTR

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In the traditional mechanical models of hard roof, multiple hard rock strata are usually taken as the overall critical stratum to analyze its movement instability characteristics while the mutual effect between two hard rock strata is neglected, so it's difficult for theoretical analysis results to realize the accurate prediction of mine pressure behaviors. The reasonable prediction of mine pressure behaviors on a fully mechanized caving face with multiple hard rock strata is ensured further by considering the geological conditions of the 1307 working face mine in Zhaoxian Coal Mine in the Yonglong Coalfield Mine area in China, a mechanical model of a hard roof structure with high and low strata (double strata) was proposed in this study, and the periodic instability step of the high-and low-level hard roofs and the change laws of support resistance on the working face were also determined. Then, the theoretical calculation results were verified according to field measurement data. Results indicate that fracturing instability does not simultaneously occurred in the high and low strata of the hard roof, as the instability steps are 106 m and 18 m, and the corresponding working resistances of the hydraulic support are 63 MPa and 37 MPa, respectively. Meanwhile, the onsite-measured mine pressure data suggest that the major-cycle cyclic weighting step is approximately 101 m, while the continuous step is approximately 12 m. The minor-cycle cyclic weighting step is within 15-25 m, the continuous step is approximately 2 m, and the peak working resistances of the hydraulic support on the average are 42.3 MPa and 36.8 MPa, respectively, so the on-site monitoring data basically accorded with the theoretical analysis results, thus verifying the scientificity of the constructed mechanical model. This study provides a theoretical reference on the safe mining of the fully mechanized caving face of a multi-stratum hard roof.

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Longwall Face Stability Index for Estimation of Chock-Shield Pressure and Face Convergence

Cited by 15 publications

References 8 publications

Field Investigation of Face Spall in Moderate Strength Coal Seam at Vang Danh Coal Mine, Vietnam

Field Investigation of Face Spall in Moderate Strength Coal Seam at Vang Danh Coal Mine, Vietnam

Roof Strata Behavior and Support Resistance Determination for Ultra-Thick Longwall Top Coal Caving Panel: A Case Study of the Tashan Coal Mine

Influence Characteristics of Double-Stratum Hard Roof Movement in a Fully Mechanized Top Coal Caving on the Working Resistance of Supports

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