The pressure relief protection effect of different strip widths, dip angles and pillar widths of an underside protective seam

Fang, Shizheng; Zhu, Hongqing; Huo, Yujia; Zhang, Yilong; Wang, Haoran; Li, Feng; Wang, Xiaokuan

doi:10.1371/journal.pone.0246199

Cited by 8 publications

(3 citation statements)

References 68 publications

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“…Liu et al [21] studied the method for determining the stress distribution in the boundary area of pressure relief during the mining of protective layers. Fang et al [22] studied the differences in the pressure relief effects of different strip widths, dip angles, and coal pillar widths in the lower protective layer. Cheng et al [23] proposed a method to mine soft rock as a UPL and analysed the influence of different mining parameters on the pressure relief effect of the protective layer.…”

Section: Introductionmentioning

confidence: 99%

Limitations of Upper Protective Layers as Pressure Relief Measures for Extra-Thick Coal Seam Mining: Insights from a Case Study

Chai,

Dou,

et al. 2024

Energies

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Upper protective layer (UPL) mining is extensively utilised as a pressure relief strategy to prevent outbursts and coal bursts. However, when the excavation height of the protected layer is substantial, the depressurisation efficacy of the protective layer may be diminished. This paper takes the Haishiwan coal mine in China as a case study and explores the stress evolution and influencing factors in the mining of extra-thick coal seam beneath the protective layer through theoretical analysis, numerical simulation, and field observation. The results indicate that increasing the excavation height of the coal seam will lead to the upward development of the collapse zone in the overburden of the goaf, with the “masonry beam” structure formed at a higher position by key strata blocks. The overburden above the masonry beam will be supported by the coal rock masse on both sides of the structure, leading to increased stress on the coal seam near the goaf and eliminating the depressurisation effect of the protective layer. Numerical simulation shows that factors such as faults, protective layers, interlayer spacing, and the height of coal seam excavation significantly affect the stress distribution in the protected layer. With the increase in interlayer spacing and the thickness of coal seam extraction, the stress reduction phenomenon of the UPL gradually decreases, especially with an abnormal stress concentration of the gob-side coal seam. Observations of Surface subsidence and the distribution of mining-induced seismic events corroborate the conclusions of theoretical analysis and numerical simulations. The results offer valuable guidance for the mining of extra-thick coal seams and the selection of the UPL.

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Section: Introductionmentioning

confidence: 99%

Limitations of Upper Protective Layers as Pressure Relief Measures for Extra-Thick Coal Seam Mining: Insights from a Case Study

Chai,

Dou,

et al. 2024

Energies

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“…If there is a coal pillar in the mined-out area in the close distance coal seams, the coal pillar has two sides at mined-out area boundary, the vertical stress is concentrated in coal pillar's floor strata, the damage degree of upper coal pillar boundary floor is large, and the damage range is affected largely by coal pillar in close upper coal seam. The damage zone and forms are the main research object when the roadway is arranged in the lower coal seam near the upper coal pillar boundary [3][4][5][6][7][8][9]. Many scholars have studied the stress distribution and the damage zone to a certain extent [4,[10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Stratification Failure Mechanism of Coal Pillar Floor Strata with Different Strength in Short Distance Coal Seams

Kang

Yin

et al. 2022

Geofluids

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The failure of strata with different strength under coal pillar in close distance coal seams has its particularity. Theoretical analysis, numerical simulation, and similar test were used to obtain the failure mechanism of the soft and hard stratification of floor strata under the boundary of wide coal pillar and make out the influence of the strata failure on roadway layout. It shows that the failure of the soft and hard stratification is not synchronous and with different failure forms. The deformation and plastic failure of the soft strata occurs at first; then the fracture of the main bearing hard stratum occurs. Based on the main bearing stratum unbalanced forces acted by upper and lower strata, the initial fracture position and broken blocks span were calculated by bending fracture mechanics model of ultimate span beam. The coal pillar side of the roadway under coal pillar forms “column-beam-column” superimposed structure. The roadway layout under coal pillar and under coal pillar boundary with close distance has large influence on the plastic extension of the “column-beam-column” superimposed structure and the broken of main bearing stratum. The influence of roadway arrangement in floor strata outside coal pillar is smaller than those under coal pillar. It is difficult to control the deformation of roadway surrounding rock if the roadway locates beneath the broken blocks of the main bearing stratum.

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“…In China, gas hazards are still a prominent problem and gas accidents are often accompanied by loss of life 1 – 5 . Gas in the upper corner of the working face is a common gas problem and is managed in a number of ways 6 , 7 .…”

Section: Introductionmentioning

confidence: 99%

Study on the optimal position of the roof low roadway based on the response surface methodology

Zhu

Fang

Huo

et al. 2021

Sci Rep

Self Cite

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For determine the optimum position of the roof low roadway, the optimal solution is derived according to the response surface methodology. The UDEC numerical simulation of the overburden gives the porosity distribution of the strike fractured zone, the upper limit heights of the caving zone and the fractured zone are obtained as 18 m and 65 m, respectively. Based on the porosity distribution, the FLUENT numerical models of the goaf zone, air inlet roadway, air return roadway, working face and roof low roadway were established to simulate the gas concentration in the upper corner and gas drainage volume in roof low roadway during mining. Using the vertical and horizontal distance of the roof low roadway as the influencing factors, the experimental scheme of the position of the roof low roadway was designed according to the response surface method, and the response values were obtained from the FLUENT simulation experiments, predicting that the vertical and horizontal distances of the roof low roadway were 7.7 m and 5.9 m respectively when the interaction between the gas concentration in the upper corner and gas drainage volume in roof low roadway was optimal. Field tests showed that the average gas concentration in the upper corner and the average gas drainage volume in roof low roadway were 0.432% and 40.861 m3/min respectively, both of which were less than 10% of the error from the simulations. The design of the roof low roadway has effectively managed the gas accumulation problem in the upper corner.

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The pressure relief protection effect of different strip widths, dip angles and pillar widths of an underside protective seam

Cited by 8 publications

References 68 publications

Limitations of Upper Protective Layers as Pressure Relief Measures for Extra-Thick Coal Seam Mining: Insights from a Case Study

Limitations of Upper Protective Layers as Pressure Relief Measures for Extra-Thick Coal Seam Mining: Insights from a Case Study

Stratification Failure Mechanism of Coal Pillar Floor Strata with Different Strength in Short Distance Coal Seams

Study on the optimal position of the roof low roadway based on the response surface methodology

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