Roof Deformation, Failure Characteristics, and Preventive Techniques of Gob-Side Entry Driving Heading Adjacent to the Advancing Working Face

Bai, Jianbiao; Shen, Wenlong; Guo, Guangli; Wang, Xiangyu; Yu, Yang

doi:10.1007/s00603-015-0713-2

Cited by 120 publications

(67 citation statements)

References 12 publications

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“…To ensure the efficient operation of coal production systems, security maintenance of entries in underground mining is extremely important, including large deformation control, rock burst forecast, and other early warnings of dynamic disaster [2][3][4]. As the development of the longwall mining, many entries are arranged along the side of a gob with a protection of coal pillar or artificial wall, so as to cope with the mining-induced movement of the hard roof structures [5][6][7]. Figure 1 schematically describes entry conditions when extracting coal from Panel 2.…”

Section: Introductionmentioning

confidence: 99%

Mining-Induced Failure Criteria of Interactional Hard Roof Structures: A Case Study

et al. 2019

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Due to the additional abutment stress, interactional hard roof structures (IHRS) affect the normal operation of the coal production system in underground mining. The movement of IHRS may result in security problems, such as the failure of supporting body, large deformation, and even roof caving for nearby openings. According to the physical configuration and loading conditions of IHRS in a simple two-dimensional physical model under the plane stress condition, mining-induced failure criteria were proposed and validated by the mechanical behavior of IHRS in a mechanical analysis model. The results indicate that IHRS, consisting of three interactional parts-the lower key structure, the middle soft interlayer, and the upper key structure-are governed by the additional abutment stress induced by the longwall mining working face. The fracture of the upper key structure in IHRS can be explained as follows: Due to the crushing failure, lower key structure, and middle soft interlayer yield, the action force between the upper and lower key structures vanishes, resulting in fracture of the upper key structure in IHRS. In a field case, when additional abutment stress reaches 7.37 MPa, the energy of 2.35 × 10 5 J is generated by the fracture of the upper key structure in IHRS. Under the same geological and engineering conditions, the energy generated by IHRS is much larger than that generated by a single hard roof. The mining-induced failure criteria are successfully applied in a field case. The in-situ mechanical behavior of the openings nearby IHRS under the mining abutment stress can be clearly explained by the proposed criteria.

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Section: Introductionmentioning

confidence: 99%

Mining-Induced Failure Criteria of Interactional Hard Roof Structures: A Case Study

et al. 2019

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“…Gob-side entry driving with narrow coal pillars is performed in the goaf along the last working face after the overlying strata of the working face is stable [9]. The mechanical model of the surrounding rock of gob-side entry driving in the fully-mechanized top-coal caving working face is shown in Fig.…”

Section: Mechanical Analysis Of Key Rock Block 311 Mechanical Modelmentioning

confidence: 99%

“…For example, Li et al [8] explored the stability principle of large and small structures by theoretical analysis, in which the main roof was part of large structures, and the control of small structure technology was proposed. Bai et al [9,10] studied the stability of an arc triangular block at the ends of working face; the supporting technology, as well as the width and location of narrow pillar, were analyzed and extensively used according to the stability. Feng et al [11] studied the influence mechanism of the caving characteristic and roof structure on roadway stability, and the optimal position for the roadway was identified and successfully applied in the Huainan Mining Areas.…”

Section: State Of the Artmentioning

confidence: 99%

“…The surrounding rock strength of small structures in roadway can affect the stress and displacement characteristics of large structures in the overlying strata, and supporting technologies of small structures directly determine the surrounding rock stability [8,9]. Key supporting technologies to surrounding rock are proposed according to stress distribution laws under different main roof heights.…”

Section: Key Supporting Technologies For Controlling Surrounding Rockmentioning

confidence: 99%

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Influence Mechanism of Main Roof Height on Surrounding Rock Stability of Gob-Side Entry Driving

Shuang

Chen

et al. 2018

Teh. vjesn.

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Abstract:The main roof directly affects the stress environment and the control effect of the surrounding rock of gob-side entry driving. A mechanical model of the surrounding rock of gob-side entry driving was established to analyze the influence mechanism of different main roof heights on the surrounding rock stability of the roadway under similar geological conditions. In addition, the influences of the main roof heights on the stress distribution of the surrounding rock were qualitatively analyzed. A quantitative analysis of the stress and deformation distribution characteristics of the surrounding rock were conducted by Universal Distinct Element Code (UDEC) when the heights were 0, 5, and 10 m based on the actual geological conditions. Results show that waste rocks in the caving zone and damaged immediate roof could provide four different stress combinations to key rock block, which is affected by the main roof height and other related parameters. With the increase in the main roof height, the hinged stress between the key rock blocks and the plastic damage area of the physical coal wall are reduced, the damage range of immediate roof gradually increases, and the vertical stress of narrow coal pillars first increases to 5.22 MPa and then remains at approximately 1.92 MPa. Therefore, the supporting strength of roof and the physical coal wall should be enhanced. Research results are successfully applied in the Yanjiahe Coal Mine. The conclusions provide significant theoretical guidance for controlling surrounding rock stability of the roadway under similar conditions.

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“…The Mohr-Coulomb failure criterion is used to simulate the rock strata and the coal seam [15,22,27]. …”

mentioning

confidence: 99%

A New Gob-Side Entry Layout Method for Two-Entry Longwall Systems

et al. 2018

Energies

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Abstract:The gob-side entry layout is popular at two-entry longwall mine sites in China for the benefit of improving the coal recovery rate. Currently, two methods have been widely used to develop gob-side entries, including gob-side entry retaining and gob-side entry driving. Gob-side entry retaining maximizes the recovery rate by pillarless mining but increases the difficulty in gob-side entry support. Also, this method has limited applications in hard roof conditions. The gob-side entry driving mine site uses the rib pillar to separate the gob entry and the gob area of the previous panel, which leads to additional coal losses. The waste is more intolerable in large-cutting-height panels and longwall top coal caving panels as the Chinese government limits the minimum recovery rate of longwall panels using these mining methods. In this paper, a new gob-side entry layout method, termed gob-side pre-backfill driving, is established to overcome the shortcomings of the existing methods. The new method eliminates rib pillar losses and enhances gob-side entry stability. The feasibility of gob-side pre-backfill driving is studied by numerical modelling and a field trial at Changcun Mine in China. The results indicate that gob-side pre-backfill driving is an alternative for gob-side entry development. This method is practical and also has the potential to bring significant economic benefits to the mining industry.

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Roof Deformation, Failure Characteristics, and Preventive Techniques of Gob-Side Entry Driving Heading Adjacent to the Advancing Working Face

Cited by 120 publications

References 12 publications

Mining-Induced Failure Criteria of Interactional Hard Roof Structures: A Case Study

Mining-Induced Failure Criteria of Interactional Hard Roof Structures: A Case Study

Influence Mechanism of Main Roof Height on Surrounding Rock Stability of Gob-Side Entry Driving

A New Gob-Side Entry Layout Method for Two-Entry Longwall Systems

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