The Key Stratum Structure Morphology of Longwall Mechanized Top Coal Caving Mining in Extra‐Thick Coal Seams: A Typical Case Study

He, Fulian; Li, Xiaobin; He, Wenjun; Zhao, Yongqiang; Xu, Zhuhe; Li, Quansheng

doi:10.1155/2020/7916729

Cited by 9 publications

(7 citation statements)

References 47 publications

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“…At present, UDEC 7.0 is an ideal software to simulate the movement of rock stratum and surface subsidence under different lithology and mining conditions. It can better simulate the process of roof separation, caving and re-compaction after coal seam mining, and can accurately analyze the breaking law of overburden 39 . The constitutive model used in this simulation is Mohr–Coulomb model.…”

Section: Numerical Simulationmentioning

confidence: 99%

Study of water-conducting fractured zone development law and assessment method in longwall mining of shallow coal seam

Han

et al. 2022

Sci Rep

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Starting from the source of mining, scientific understanding of surface damage law and assessment method in longwall mining of shallow coal seam is conducive to solving the problems of geological hazards and deterioration of the ecological environment, and promoting the coordinated development of efficient coal mining and environmental protection. Based on numerical simulation and theoretical analysis, the surface damage process and spatiotemporal evolution of fracture field are discussed. The influencing factors and assessment method of surface damage are clarified. The results show that surface damage undergone the immediate roof caving stage, the fracture and instability stage of main roof, the spatial amplification stage of separation layer, the instability stage of surface damage control layer and the mining damage stability stage. Under the critical extraction condition, the cracks above the goaf are divided into the crack area outside the cut, the crack area inside the cut, the re-compaction area in the middle goaf, the crack area behind the longwall face, and the crack area in front of the longwall face. The overburden reaches critical failure ahead of surface critical mining. The sensitivity of loose layer thickness to surface subsidence coefficient is greater than that of mining thickness to surface subsidence coefficient. Surface damage control should be adjusted to local conditions, and finally realize zoning treatment and zoning repair. Through the three-step method of "longwall face rapid advancing method, local grouting reinforcement overburden method and zoning treatment ground fissures method", the surface damage control of 12,401 longwall face is realized. This research provides theoretical guidance and application value for surface ecological restoration in similar mining area.

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Section: Numerical Simulationmentioning

confidence: 99%

Study of water-conducting fractured zone development law and assessment method in longwall mining of shallow coal seam

Han

et al. 2022

Sci Rep

Self Cite

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“…Numerical Model. e numerical calculation model is established by Universal Distinct Element Code (UDEC) simulation software [29,30]. As shown in Figure 12, there are two groups of the KS in the model.…”

Section: Numerical Simulation Of the Fracture Of The Overlying Stratamentioning

confidence: 99%

Fracture Mechanism in Overlying Strata during Longwall Mining

Zheng-yi

Wang

et al. 2021

Shock and Vibration

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We used the key stratum theory to establish a more realistic thin-plate mechanical model of elastic foundation clamped boundary and study the fracture mechanism of overlying strata during longwall mining. We analyzed the fracture characteristics and factors affecting fracture of the key stratum combined with the Mohr–Coulomb yield criterion. Besides, we used numerical simulation methods to verify the evolution pattern of the overlying strata fracture. The results show that the fracture mechanisms of the elastic foundation clamped structure’s key stratum varied depending on the position under longwall mining. The advanced coal wall area of the upper surface is a compressive-shear fracture. The center area of the lower surface is a tensile fracture. With the increase of the excavation length and the load of the key stratum, the central area and the advanced coal wall area of the long side are fractured before the advanced coal wall area of the short side. With the increase of flexural rigidity of the key stratum, the advanced coal wall area of the long side fractures before the central area and the advanced coal wall area of the short side. With the increase of the foundation modulus and the advanced load of the key stratum, the central area fractures before the surrounding advanced coal wall area. The advanced influence distance was positively correlated with the key stratum’s flexural rigidity and advanced load and negatively correlated with the foundation modulus and excavation length. The advanced influence distance was not affected by the load of the key stratum. The numerical simulation results show that, with the increase of the mining area, the fracture trace of overlying strata in goaf extended to the coal wall’s interior. The fracture range of overlying strata is larger than that of the miningd: area. This study has a practical value for water disasters, gas outbursts, and rock strata control.

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“…Due to the complex engineering conditions of coal seam mining, the simpli cation of the theoretical model often has a great impact on the analysis results. Therefore, many scholars have also paid attention to the actual measurement research of engineering, and have studied the development height and distribution law of coal seam roof cracks through a large number of eld observations [12][13][14] .…”

Section: Introductionmentioning

confidence: 99%

Research on the dynamic evolution law of fissures in shallow-buried and short-distance coal seam mining in Lijiahao Coal Mine

Wang

Zhou

Zhang

et al. 2023

Preprint

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The leftover coal in the Lijiahao Coal Mine is easy to spontaneously ignite. During the mining process of the shallow buried coal seam, the overlying fissure network in the goaf easily penetrates the goaf of the upper and lower coal seams and continues to the surface, resulting in air leakage in the mine and the hidden danger of spontaneous combustion of the leftover coal protrude. Through physical model experiments, this paper simulates the overburden structure and fracture development characteristics of Lijiahao shallow buried coal seam mining, and uses fractal dimension and image processing technology to quantitatively describe the generation and development process of overburden cracks. Combined with the classical mechanical model of "fixed beam" and "masonry beam", the causes of fracture dynamic evolution are analyzed. The results show that due to the existence of key layers between the coal seams, the stress evolution in the upper and lower seams of the key layer is not synchronised, with only small changes in stress in the upper layer before the key layer is broken, and the stress evolution in the lower layer is similar to that of a single coal seam mining. When the key layer is broken, the stress of the upper and lower rock layers will change dramatically; the fracture of the key layer also has a significant impact on the evolution of fracture fractal dimension, length, and area. The fractal dimension of the fissures rised from 1.4 to 1.5, the total area of fissures is increased from 16638 pixels to 17707 pixels, and the total length is increased from 2217 pixels to 3071 pixels; after the main key layer of the overlying rock is broken, the fractal dimension of the fissures is reduced from 1.56 to 1.5, and the total area of fissures is reduced from 31451 pixels to 29089 pixels, the total length has increased from 5657 pixels to 6619 pixels; before the key layer between the coal seams is broken, it will be suspended to form a "fixed beam". After the first break, the broken rock above it will settle synchronously until the rock blocks form a hinged structure and then collapse. After the fall stops, the key layer periodically breaks to form a "masonry beam" structure, and the overlying stratum settles synchronously. Due to the good integrity of the overlying strata, the secondary development of cracks is relatively moderate.

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The Key Stratum Structure Morphology of Longwall Mechanized Top Coal Caving Mining in Extra‐Thick Coal Seams: A Typical Case Study

Cited by 9 publications

References 47 publications

Study of water-conducting fractured zone development law and assessment method in longwall mining of shallow coal seam

Study of water-conducting fractured zone development law and assessment method in longwall mining of shallow coal seam

Fracture Mechanism in Overlying Strata during Longwall Mining

Research on the dynamic evolution law of fissures in shallow-buried and short-distance coal seam mining in Lijiahao Coal Mine

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