Feasibility study on multi-seam upward mining of multi-layer soft–hard alternate complex roof

Liu, Yuben; Cheng, Jiulong; Jiao, Jianling; Meng, Xiangxi

doi:10.1007/s12665-022-10537-z

Cited by 12 publications

(6 citation statements)

References 35 publications

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“…Resistivity measurement is an ideal method for evaluating the filling effect, which is based on detecting the conductivity of the slurry and coal gangue, and it integrates the detection of the slurry diffusion depth and the slurry–rock boundary. − By using a one-time arrangement of electrodes, using a CNC electrode converter and an electrical instrument, the measurement line can be quickly measured, collected, and the data can be stored. Professional software is used to draw a resistivity map that reflects the diffusion of the filling slurry, and comprehensive analysis and evaluation of the filling effect in the mine are conducted.…”

Section: Experimental Results Analysismentioning

confidence: 99%

Experimental Study on the Diffusion Law of Coal-Based Solid Waste Slurry with Grouting Filling in the Gangue Voids of the Caving Zone

Xiang,

Zhen,

et al. 2023

ACS Omega

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Due to the concealment of the caving zone, it is difficult to detect and grasp the diffusion law of the slurry in the voids of the gangue pile. On the preparation of reasonable grouting filling materials, a large-scale three-dimensional gangue grouting filling test system has been established to detect the slurry pressure and resistivity inside the gangue pile and analyze the flow pattern of the slurry in the voids of the gangue pile. The research results show that the slump and bleeding rate of the filling slurry are significantly reduced with the increase of the fly ash content. The optimal ratio of fly ash, coal gangue, and gasification slag is 7:2:1, with a mass fraction of 72%. In the process of grouting, the internal pressure of the gangue pile can be divided into the initial stable stage, the step growth stage, and the pressure stability stage, and the change curve of the pressure sensor at the lower level is similar. The resistance value of the original broken gangue in the experiment is approximately 1600 Ω. Grouting filling forms a slurry−rock mixture, and its resistance continuously decreases with the stable injection of the slurry (minimum value 150 Ω). It is determined that the slurry near the grouting hole mainly diffuses longitudinally with a good void filling effect. The void channels of slurry diffusion are randomly distributed and have different shapes, which hinder slurry flow and diffusion. Slurry particles accumulate and settle at local small voids. Meanwhile, the surface of the gangue blocks is dry, and the slurry absorbs part of the water during diffusion, resulting in the increase of the slurry concentration and the weakening of the lateral diffusion ability. Secondary or multiple grouting can effectively fill the void of the broken gangue and further improve the filling effect.

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Section: Experimental Results Analysismentioning

confidence: 99%

Experimental Study on the Diffusion Law of Coal-Based Solid Waste Slurry with Grouting Filling in the Gangue Voids of the Caving Zone

Xiang,

Zhen,

et al. 2023

ACS Omega

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“…Studies indicate that a prerequisite for upward mining is to extract the lower coal seam without compromising the integrity and continuity of the overlying upper coal seam [27][28][29][30][31][32][33]. The feasibility of upward mining in the 1515 mining face was assessed by three methods, namely, the ratio discrimination method, the rock balance discrimination method, and the discrimination method of "three zones" [34].…”

Section: Upward Mining Feasibility Assessmentmentioning

confidence: 99%

Calculation Method of Support Load Zoning and Mechanism of Mine Pressure Behavior in Upward Mining Face across Half of the Goaf along the Panel Direction

Zhang,

Ma,

Feng

et al. 2024

Processes

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The 1515 mining face in Yongming Coal Mine was upward mined across half of the goaf along the panel direction. In this paper, the methods of field measurement, theoretical analysis, and numerical simulation were used to study the overlying rock fracture structure, support load characteristics, and the mechanism of mine pressure behavior across half of the goaf. The results indicate that the support load of the 1515 upward mining face across half of the goaf along the panel direction exhibits distinct zoning characteristics. The maximum support load is 1.37 times the minimum support load. The development height of the roof separation in the up-mining area is 1.74 times that in the entity coal area, at 9.1 m and 5.22 m respectively. The height of separation and hanging roof length increase and decrease, respectively, along the initial rock fracture area, tensile fracture area, structural fracture area, and compacted fracture area. Based on the definition of the variation coefficient “m” for immediate roof height and hanging roof coefficient “n”, a partitioned method for calculating support loads in the upward mining face across half of the goaf was proposed. Finally, the key parameter values for support loads in each zoning were provided and validated.

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“…Due to historical and technological limitations, China's residual coal reserves are estimated to be around 40 billion tons, of which 34% to 45% needs to be mined through upward mining [1]. Feasibility determination is the core prerequisite for upward mining [2,3]. The current methods used to determine the feasibility of upward mining have developed from empirical determination into quantitative determination.…”

Section: Introductionmentioning

confidence: 99%

“…However, the critical range of the mining influence factor is from 6 to 20, and the two critical values for OB/IB are 7 and 16, with a wide range of variation for the critical values. Both the statistical method and "three-zone" method are also related to M and H [8][9][10][11], and they, respectively, assert that when H satisfies Equations ( 1) and (2), upward mining can be carried out: H > 1.14 M 2 + 4. 14 (1…”

Section: Introductionmentioning

confidence: 99%

A Disturbed Voussoir Beam Structure Mechanical Model and Its Application in Feasibility Determination of Upward Mining

Zhang,

Wang,

Cui

et al. 2023

Energies

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China is endowed with a large quantity of residual coal resources that require upward mining. The stability of interburden strata structures and accurate determination are crucial for safe mining. Therefore, we established a mechanical model of disturbed voussoir beam structures of interburden strata in upward mining. The model was solved, and stability analysis and instability mechanism analysis were conducted. Based on this model, a new method for determining the feasibility of upward mining was proposed and applied to the upward mining of coal seam No. 7 in Baijiazhuang Coal Mine. A physical simulation experiment and numerical simulation were conducted to validate the method. Through research, it was found that the model had two instability mechanisms: rotation instability and sliding instability. When the disturbance load crossed the critical block of the structures, the model was most likely to experience sliding instability. When the disturbance load acted entirely on the critical block, rotation instability was more likely to occur. The result of the determination, performed using the new method, showed that there was no rotation instability or sliding instability in the interburden strata structures of coal seam No. 7, indicating that the coal seam could be mined upward. This result was consistent with the determinations using the statistical method, “three-zone” method, and balanced surrounding rock method. Physical and numerical simulations revealed that the upward mining of coal seam No. 7 caused the subsidence, rotation, and separation compaction of the interburden strata structures but that the structures remained stable. The results indicate that the proposed model and method have accuracy and applicability, being able to guide the practical feasibility determination of upward mining.

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Feasibility study on multi-seam upward mining of multi-layer soft–hard alternate complex roof

Cited by 12 publications

References 35 publications

Experimental Study on the Diffusion Law of Coal-Based Solid Waste Slurry with Grouting Filling in the Gangue Voids of the Caving Zone

Experimental Study on the Diffusion Law of Coal-Based Solid Waste Slurry with Grouting Filling in the Gangue Voids of the Caving Zone

Calculation Method of Support Load Zoning and Mechanism of Mine Pressure Behavior in Upward Mining Face across Half of the Goaf along the Panel Direction

A Disturbed Voussoir Beam Structure Mechanical Model and Its Application in Feasibility Determination of Upward Mining

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