Numerical Study of Failure Mechanisms and Control Techniques for a Gob-Side Yield Pillar in the Sijiazhuang Coal Mine, China

Wu, Weili; Bai, Jianbiao; Wang, Xiangyu; Yan, Shuai; Wu, Shao-xu

doi:10.1007/s00603-018-1654-3

Cited by 89 publications

(53 citation statements)

References 24 publications

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“…According to the geological and mining conditions of the 1103 working face in the Heilong Coal Mine, a numerical model was established using the discrete element method software UDEC [46,47].…”

Section: Numerical Model and Verificationmentioning

confidence: 99%

Gob-Side Entry Retained with Soft Roof, Floor, and Seam in Thin Coal Seams: A Case Study

et al. 2020

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Gob-side entry retained technology is of great significance to develop coal mining industry sustainably, which can improve the coal recovery rate by mining without the coal pillar. However, scholars and researchers pay little attention to the gob-side entry retained with soft roof, floor, and seam in thin coal seams. In this study, the difficulties and key points of surrounding rock control for gob-side entry retained with soft roof, floor, and seam in thin coal seams were firstly proposed. Secondly, the mechanical model of the interaction between the roadside backfill body and the roof for gob-side entry retained with soft roof, floor, and seam in thin coal seams was established, and the relevant parameters were designed. Finally, the above results were verified by the engineering practice of gob-side entry retained technology and the monitoring of mine pressure on the 1103 working face of the Heilong Coal Mine. Moreover, the effect factors of surrounding rock stability for gob-side entry retained with soft roof, floor, and seam in thin coal seams were discussed using the discrete element method. The results could provide guidance for gob-side entry retained with soft roof, floor, and seam in thin coal seams under similar geological conditions.

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Section: Numerical Model and Verificationmentioning

confidence: 99%

Gob-Side Entry Retained with Soft Roof, Floor, and Seam in Thin Coal Seams: A Case Study

et al. 2020

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“…The ultimate value of the deflection for the upper key structure can be calculated in Equation (21). The additional abutment stress reaches the limitation value, once the action force F p between the upper and lower key structure reaches the limitation value of F p in Equation (7). Thus, the final calculation method of the limitation of the additional abutment stress can be obtained by taking the Equation (7) and Equation (21) into Equation (20), as shown in Equation (22).…”

Section: Limitation Of the Additional Abutment Stressmentioning

confidence: 99%

“…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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“…[3][4][5] These hazards represent a severe danger to safe production and pose a new challenge to achieving hard roof control in ETCSM. [6][7][8][9] According to incomplete statistics, up to 132 SGP activities (the shrinkage of the support pillar exceeding 600 mm) have been recorded in Tashan and Tongxin coal mines since the ETCSM in 2008, of which approximately 21 frame-pressing accidents occurred in stopes. These problems are not unique in China, and have been reported in India and the USA.…”

Section: Introductionmentioning

confidence: 99%

Determination of the key parameters of high‐position hard roofs for vertical‐well stratified fracturing to release strong ground pressure behavior in extra‐thick coal seam mining

Pan

Xia

et al. 2020

Energy Science & Engineering

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Traditional methods of controlling hard roofs have a limited scope of action and cannot effectively release the strong ground pressure behavior (SGPB) induced by high-position hard roofs (HHRs) in extra-thick coal seam mining (ETCSM). Thus, an innovative control technology of fracturing HHRs by vertical-well stratified fracturing (VWSF) has been proposed. However, the key parameters of VWSF, namely fracturing horizon and fracturing thickness of HHRs, which have a significant influence on stope stability, remain uncertain. In this study, a mechanical model of the "coal wall-hydraulic support-gangue" support system is established by considering the effective loading acting on HHRs, through which modified expressions for the periodic breaking span and impact kinetic energy of the stope are deduced. Based on the self-bearing of bulking rocks, the stability principle of the surrounding rock, and energy dissipation theories, the criteria for determining the fracturing horizon and thickness of the HHR are obtained. Next, a numerical model of ETCSM, which accounts for the supporting effect of gangue, is constructed in FLAC3D. The support load and energy released by stratum breakage are determined through modeling under various hard roof parameters, thus verifying the correctness of the determination criteria. The results show that the energy released by a hard roof, average support load, and critical support load are positively correlated with thickness, and first increase before declining with respect to an increase in the fracturing horizon.The key parameters for a real coal mine are obtained by theoretical calculations and numerical simulations. A field application demonstrates that the support load and advance roadway deformation can be decreased using the proposed parameterization. This provides theoretical support for determining the key parameters of HHRs for VWSF and facilitates the widespread application of VWSF technology in HHR control. K E Y W O R D Shigh-position hard roofs, microseismic monitoring, mine safety, strong ground pressure behavior, vertical-well stratified fracturing | 2217 PAN et Al.

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Numerical Study of Failure Mechanisms and Control Techniques for a Gob-Side Yield Pillar in the Sijiazhuang Coal Mine, China

Cited by 89 publications

References 24 publications

Gob-Side Entry Retained with Soft Roof, Floor, and Seam in Thin Coal Seams: A Case Study

Gob-Side Entry Retained with Soft Roof, Floor, and Seam in Thin Coal Seams: A Case Study

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

Determination of the key parameters of high‐position hard roofs for vertical‐well stratified fracturing to release strong ground pressure behavior in extra‐thick coal seam mining

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