Study on Stress Evolution Law of Overburden under Repeated Mining in Long-Distance Double Upper Protective Layer

Fang, Shengjie; Li, Bing; Sun, Weiji; Shi, Zhanshan; Hao, Jianfeng; Wang, Beifang; Zhang, Xiaoyong

doi:10.3390/en15124459

Cited by 9 publications

(4 citation statements)

References 22 publications

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“…To objectively reflect the development and fracture of intrusive rock fracture caused by underground coal seam mining, according to the actual engineering conditions, the test model is required to have a certain similar relationship in various physical quantities such as geometric shape, bulk density, and stress according to the similarity law. The geometric similarity ratio is a l = 100; the similar constant of bulk density: a r = 1.6; the time scale can be obtained according to the conversion relationship between the time similarity ratio and the geometric similarity ratio: a t = √ a l = 10 [25,26].…”

Section: Similar Materials and Ratiomentioning

confidence: 99%

Study on Fractal Characteristics of Evolution of Mining-Induced Fissures in Karst Landform

et al. 2022

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The karst landscape is widespread in the southern region of China. As a result of underground mining activities, the original stress equilibrium is disrupted, causing the redistribution of stress in the overlying rock layer, inducing the longitudinal fracture of mining to expand and penetrate upwards, resulting in the rupture and destabilization of the karst cave roof, thus triggering a series of engineering problems such as karst cave collapse, landslide, the discontinuous deformation of the ground surface, and soil erosion. In order to study the evolutionary characteristics of buried rock fissures in shallow coal seam mining under the karst landform, taking the shallow coal seam with the typical karst cave development landform in Guizhou as the engineering background, based on the similarity simulation experiment and fractal theory, the evolution law of buried rock fissures and network fractal characteristics under the disturbance of the karst landform mining are analyzed. The research shows that the mining-induced fracture reaches the maximum development height of 61 m on the left side of the cave, and the two sides of the cave produce uncoordinated deformation. The separation fracture below the cave is relatively developed, and the overall distribution pattern of the cave rock fracture network presents a “ladder” shape. The correlation coefficient of the fractal dimension of the rock fractures under different advancing distances is more than 0.90, and the rock fracture network under the karst landform has high self-similarity. The variation of fractal dimension with the advancing degree of the working face can be divided into four stages. The first and second stages show an exponential growth trend, and the third and fourth stages show linear changes with slopes of 0.0007 and 0.0014, respectively. The fluctuation of the fractal dimension is small. The periodic weighting of the upper roof in the cave-affected zone is frequent, the fragmentation of the fractured rock mass becomes larger, and the fractures of the upper rock mass are relatively developed. The research results can provide a reference for the study on the evolution law of mining-induced rock fissures under similar karst landforms.

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Section: Similar Materials and Ratiomentioning

confidence: 99%

Study on Fractal Characteristics of Evolution of Mining-Induced Fissures in Karst Landform

et al. 2022

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“…When it occurs, hundreds of tons of coal and rock are suddenly thrown out and carrying a large amount of gas can cause underground workers to be impacted, buried, suffocated, and injured. Also the equipment and facilities were damaged and even caused gas and coal dust explosions. − Protective layer mining is the most effective way to prevent the danger of coal and gas outbursts. − This process is achieved by mining the adjacent coal seam (i.e., the protected seam) before the outburst coal seam (i.e., the protected seam). , After the protective layer is mined, the pressure of the adjacent coal seam is relieved and cracks are generated, which changes the stress balance state of the original rock, increases the permeability of the coal seam, , and releases gas in the protected layer. The use of surface mining wells for coalbed methane extraction has the significant advantages of high drainage concentration and large flow. − The entire construction process is located on the ground and does not affect the coal production.…”

Section: Introductionmentioning

confidence: 99%

Optimization of the Layer Location of Extraction Wells Based on the Unpressurized Gas Transport Law

Lv,

Guo,

Zhu

et al. 2024

ACS Omega

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Protective layer mining is one of the most effective measures to control outbursts of coal seam gas in coal mines. Accurately grasping the overlying rock movement and pressurerelief gas migration patterns under protective layer mining conditions is a prerequisite for efficient surface coalbed methane extraction; it is the basis for green emission reduction in coal mines. A physical model was established using the Ji 15 -33200 working face of Pingmei Shi Mine as the research object, and a method combining theoretical calculation and numerical simulation was used to obtain the overlying rock movement. In situ stress distribution characteristics of the stope after the upper protective layer was mined to explore the upper protective layer migration rules of pressure-relief gas after mining. On this basis, the location and layer of surface coalbed methane production wells was determined. The research results show that the coal and rock formations on the floor of the goaf experienced a deformation process of compression → expansion → rebalance during the mining process; the stress changes of the overlying and underlying coal strata in the goaf have experienced a process of increasing → decreasing → rebalance; and gas migrates upward through the fissure zone in the coal layer and slowly diffuses in other microfissure areas. When the pressure reaches a certain value, it is enriched in the crack development area and the upper part of the fissure zone; combined with the relevant geological conditions of the study area, it was determined that the upper part of the roof of the Ji 16−17 coal seam is a gas-rich area. By comparing three mining vertical wells at different positions in the horizontal direction, it was found that the extraction effect was significant in the "O″ ring, near the excavation face.

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“…Li et al 31 studied the evolution process of on‐site permeability after remote protective layer mining (maximum layer spacing: 54.1 m), indicating the relationship between permeability and ground stress changes. Fang et al 32 studied the stress evolution law of the protected layer in remote double upper protective layer mining (the layer spacing is 80 and 170 m, respectively), and proved the effectiveness of the protection effect through field verification.…”

Section: Introductionmentioning

confidence: 99%

Study on stress evolution law of upper coal seam in long‐distance advance mining of lower coal seam

Fang

Sun

et al. 2023

Energy Science & Engineering

Self Cite

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With the shift of coal resources to deep mining, the occurrence of longdistance coal seams has increased, and protective layer mining is facing new challenges. This paper attempts to explain the stress evolution law of the upper coal group in the long-distance mining of the lower coal group in Pingdingshan No. 8 Coal Mine. A simulation model of advance mining of lower-group coal long-distance was established. The stress evolution law of the upper coal seam under the influence of advanced mining disturbance of the lower coal seam is studied. The following conclusions were obtained: The advance mining of the lower coal group had a positive or negative impact on the stress distribution of the upper coal seam group. With the recovery of the lower coal group of the F-21030 working face, the overburden of the F-21030 goaf finally formed a "Y" type pressure relief area. The pressure relief effect of the E-21070 working face near the stopping line was obvious. The coal seam of Group E was divided into three areas affected by the advance mining of the lower coal seam. The maximum pressure relief value was 6.6% lower than the initial stress.According to the simulation results, the E-21070 working face was divided into three regions, namely, the pressure relief region, the stress increase region, and the original stress region. According to the field drainage results of pressure relief gas, the extraction curve could be divided into three parts, namely, the stable area, pressure relief area, and stress recovery area. The maximum pure gas drainage volume could reach seven to eight times of the original area. The pressure relief extraction effect was remarkable, and the optimal extraction range was 22-210 m behind the coal face of the group.

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Study on Stress Evolution Law of Overburden under Repeated Mining in Long-Distance Double Upper Protective Layer

Cited by 9 publications

References 22 publications

Study on Fractal Characteristics of Evolution of Mining-Induced Fissures in Karst Landform

Study on Fractal Characteristics of Evolution of Mining-Induced Fissures in Karst Landform

Optimization of the Layer Location of Extraction Wells Based on the Unpressurized Gas Transport Law

Study on stress evolution law of upper coal seam in long‐distance advance mining of lower coal seam

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