A General Review on Longwall Mining-Induced Fractures in Near-Face Regions

Bai, Qingsheng; Tu, Shihao

doi:10.1155/2019/3089292

Cited by 63 publications

(28 citation statements)

References 107 publications

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“…13b. Therefore, the upper side (tailgate side) witnesses a better pressure relief effect, which results from the higher recovery goaf stress at the bottom side (headgate side) of the panel (Bai & Tu, 2019).…”

Section: Determination Of Pressure Relief Anglementioning

confidence: 99%

Characterizing the Permeability and Methane Release with the Treatment of Pressure-relief Mining: Intensive Field Measurements

Zhang

Bai

Song

et al. 2020

Preprint

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Characterizing the permeability evolution and methane release is of great significance for the safe mining of the high gas outburst seams, as well as coal and gas simultaneous extraction. Theoretical analysis, laboratory testing, and numerical simulation are widely used methods to characterize the permeability and methane release with the treatment of pressure-relief mining. However, these methods cannot fully reflect the complexity of filed practice. In this study, we report the effectiveness of protective coal seam (PCS) mining and the pressure-relief area in the protected coal seam (PDCS) based on detailed and integrated field measurements in a Chinese coal mine. To the best of our knowledge, it is the first time to measure the permeability coefficient and gas pressure evolution in the PDCS during the PCS longwall mining. The evolution of the permeability coefficient in the pressure-relief area during PCS mining can be divided into four stages: slowly decreasing, sharply increasing, gradually decreasing, and basically stable. The maximum permeability coefficient is 322 times of the initial value and finally stabilized at 100 times after the goaf compacted. The gas pressure evolution in the PDCS indicates that the strike pressure relief angle is 52.2° at the active longwall face zone, and 59.3° at the installation roadway side. The tendency pressure relief angles at the lower and upper sides of the longwall panel are 75° and 78.9°, respectively. The residual gas content and gas pressure of the PDCS in the pressure-relief area are reduced to less than 6 m3/t and within 0.4 MPa, respectively. The field measurements show that pressure-relief mining can prevent coal and gas outbursts in PDCSs. The field observations in this paper can serve as benchmark evidence for theoretical analysis and numerical simulations, and also provide insights into realizing safety mining in similar conditions.

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Section: Determination Of Pressure Relief Anglementioning

confidence: 99%

Characterizing the Permeability and Methane Release with the Treatment of Pressure-relief Mining: Intensive Field Measurements

Zhang

Bai

Song

et al. 2020

Preprint

Self Cite

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“…The studies of basic theories of FMTC mainly focus on the relationship between supports and surrounding rock failure mechanisms of top‐coal and top‐coal caving. The studies of top‐coal caving directly determine operational parameters of FMTC on site, and broken lumpiness of top‐coal directly affects recovery of top‐coal, while failure of top‐coal is a mechanical response under mining‐induced stress . Therefore, the evolution of mining‐induced stresses is one of the key problems facing those studying basic theories of FMTC.…”

Section: Introductionmentioning

confidence: 99%

Evolution of mining‐induced stress in fully mechanized top‐coal caving under high horizontal stress

Huo

Song

Sun

et al. 2020

Energy Science & Engineering

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In fully mechanized top-coal caving (FMTC), the effects of coal caving are closely related to the degree of damage to the top-coal which is determined by the stress state therein. Therefore, research into the evolution of mining-induced stress field is key to understanding failure mechanisms of top-coal. By taking the 12 309 FMTC face in Wangjialing Coal Mine (China) as the engineering background and using field measurement and numerical simulation, we studied the evolution of the principal stress field in FMTC under high horizontal stress. The research results demonstrated that in situ stress in Wangjialing Coal Mine was a high horizontal stress and lateral pressure coefficients in the north-south and east-west directions were 1.52 and 0.45, respectively. Under the influence of mining, principal stresses were concentrated in front of the coal wall, with concentration factors of 2.26, 2.24, and 2.85, respectively. The minimum principal stress in unconstrained sides of the top-coal in the roof-control zone was tensile. The directions of intermediate and minimum principal stresses in the top-coal were more sensitive to the influence of mining compared to the maximum principal stress. During rotation of the principal stress direction in topcoal, the location (19 m in front of the coal wall) where the maximum and intermediate principal stresses were equal and the location of the coal wall are key positions.

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“…Longwall mining is the most common underground mining method in the world [1][2][3]. With the reduction of coal resources, there are problems in traditional underground coal mining, such as unaffordable driving costs, large surface disturbances, low coal-extraction rates, and the frequent occurrence of safety accidents.…”

Section: Introductionmentioning

confidence: 99%

Stability Analysis of the Entry in a New Mining Approach Influenced by Roof Fracture Position

Yang

Wang

et al. 2019

Sustainability

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Non-coal pillar mining with roadway formed automatically (RFANM) is a new mining approach, which demonstrates revolutionary significance because it does not require making roadway before mining and coal pillar retaining. In order to explore the stability of the surrounding rock structure in RFANM, the deformation of the surrounding rock was theoretically analyzed and simulated based on three different fracture positions of the main roof. It was concluded that reasonable control of temporary support strength in roadway is of great importance to control the deformation of the entry. The deformation process of surrounding rock under different fracture positions in RFANM was simulated by using the Universal Discrete Element Code (UDEC). The results of the numerical simulation showed that the main roof was fractured at the solid coal side or gob side; the deformation of the roadway was small. The fracture condition of the main roof at the gob side required a higher effect of roof slitting or temporary support from the roadway. Through drilling and peeping at the retained roadway, it was judged that the main roof was broken inside the coal wall. Field monitoring results revealed that the deformation of the roadway can be effectively controlled.

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A General Review on Longwall Mining-Induced Fractures in Near-Face Regions

Cited by 63 publications

References 107 publications

Characterizing the Permeability and Methane Release with the Treatment of Pressure-relief Mining: Intensive Field Measurements

Characterizing the Permeability and Methane Release with the Treatment of Pressure-relief Mining: Intensive Field Measurements

Evolution of mining‐induced stress in fully mechanized top‐coal caving under high horizontal stress

Stability Analysis of the Entry in a New Mining Approach Influenced by Roof Fracture Position

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