Field and numerical investigations of gateroad system failure under an irregular residual coal pillar in close‐distance coal seams

Shang, Hefu; Ning, Jianguo; Hu, Shengmin; Yang, Shuai; Qiu, Pengqi

doi:10.1002/ese3.455

Cited by 34 publications

(25 citation statements)

References 32 publications

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“…The applicability of the criterion to other roadways, whose instability is mainly attributed to the retreat of longwall panels, needs further investigation. This is because longwall-affected roadways may experience different failure mechanism, [43][44][45][46][47] comparing to the roadway failure caused by high in situ stress condition.…”

Section: Discussionmentioning

confidence: 99%

Depressurizing boreholes for mitigating large deformation of the main entry

Wang

Zheng

Shen

et al. 2019

Energy Science & Engineering

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The main entries in longwall coal mine frequently encounter large deformation, depending on the stress environment. Depressurizing boreholes are applicable to reduce the large deformation; however, it is difficult to determine the proper parameters (diameter and spacing) for an effective implementation. This study aims to propose feasible design criteria for the quantification of those parameters. We first developed a rigorous numerical model, for a roadway in Zhangshuanglou coal mine, using the rock mechanical properties determined from extensive laboratory measurements and analyses. We then investigated the dependency of the stress transfer and roadway deformation on the ratio of borehole diameter and spacing (D/R and D/I). The symbols of D, R, and I represented the diameter, row spacing, and interspacing of the boreholes, respectively. We found that (a) D/R has to be between 1:6 and 1:2; and (b) D/I has to be between 1:6 and 1:4, for sufficient depressurization in the surrounding rocks. The optimized borehole diameter and spacing parameters were applied in the field where the deformation of roadway was significantly reduced. Finally, we proposed a criterion to determine those parameters of depressurization boreholes for application in other geological and mining conditions.

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Section: Discussionmentioning

confidence: 99%

Depressurizing boreholes for mitigating large deformation of the main entry

Wang

Zheng

Shen

et al. 2019

Energy Science & Engineering

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“…Entry layout has been widely used to protect this kind of entry from stress concentration disaster [11][12][13]. e pressure diffusion angle was used to design the entry layout below the bearing coal pillar, and the stress was divided into stress reducing area and stress increasing area, which ignored the influence of the abnormal stress condition [14].…”

Section: Introductionmentioning

confidence: 99%

Mining‐Induced Redistribution of the Abnormal Stress under the Close Bearing Coal Pillar for Entry Design

Shen

Bai

et al. 2021

Advances in Civil Engineering

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Underground space is vulnerable to large deformation influenced by the abnormal stress induced by the bearing coal pillar. A numerical simulation model was established to determine the redistribution of the abnormal stress induced by the mining activities. The double-yield model, the strain softening model, the interface model, and the Mohr–Coulomb model were determined to simulate the gob compaction effect, the pillar strength reduction effect, the structure plane discontinuity effect, and the rock mechanical behavior, respectively. This numerical simulation model is reliable to predict the abnormal stress under the bearing coal pillar by the comparison of the abutment stress from this model and the existing theoretical model as well as the entry roof surface displacement from this model and the field measuring method. The results from the validated numerical model indicate that the abnormal stress including stress concentration coefficient, stress gradient, and lateral pressure coefficient will redistribute to another state that the stress concentration coefficient and stress gradient increase gradually and then decrease, and the lateral pressure coefficient decreases gradually, then increases, and finally decreases sharply with the approach of the mining working face. Their maximum increasing rates are calculated as 121.05%, 198.56%, and 236.82%, respectively. This predicted mining-induced redistribution of the abnormal stress is available for designing the underground entry layout in the determination of the entry position, determination of the driving operation time, mining disturbing range warning, and the prediction of the strengthening support area.

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“…With the increasing intensity of coal mining, coal seams with favorable geological structure and shallow depths are diminishing continuously. In recent years, miners have had to overcome the challenge of coal extraction from close‐distance coal seams at many mining regions . A number of studies have already been performed to resolve the issues encountered during the mining of close‐distance coal seams.…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, miners have had to overcome the challenge of coal extraction from close-distance coal seams at many mining regions. [8][9][10][11][12][13][14] A number of studies have already been performed to resolve the issues encountered during the mining of close-distance coal seams. In these studies, the thickness of strata between close-distance coal seams is over 8 m. The numerical calculation is a commonly used method to study the stress distribution law and rock movement in close-distance coal seams (Table 1).…”

Section: Introductionmentioning

confidence: 99%

Study on the movement characteristics of the overlying stratum and surrounding rock control in ultraclose coal seams: A case study

Zhu¹,

Yao²,

Xia³

et al. 2020

Energy Science & Engineering

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In Fucun Coal Mine, the average spacing between the 3upper coal seam (UCS) and 3lower coal seam (LCS) is only 6 m. In the process of mining upper coal, the lower roadway (LR), which is 60 m away from upper pillar, becomes unstable. In order to control the surrounding rock of lower roadway, a physical model experiment and a 3D numerical calculation were performed in this study. The results of physical similarity simulation experiment show that mining of longwall face in UCS will lead to fracturing of key layers at a high elevation (KLHE) far away from the coal seam. The expanded goaf area caused large‐scale fracturing and rotation of the KLHE, which resulted in significant strata pressure behavior in LR. The numerical calculation results show that the LR should be within 19 m of the coal pillar. Finally, a plan which includes a proper location and a supporting system was proposed. The feasibility of the proposed plan is verified by an industrial application.

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Field and numerical investigations of gateroad system failure under an irregular residual coal pillar in close‐distance coal seams

Cited by 34 publications

References 32 publications

Depressurizing boreholes for mitigating large deformation of the main entry

Depressurizing boreholes for mitigating large deformation of the main entry

Mining‐Induced Redistribution of the Abnormal Stress under the Close Bearing Coal Pillar for Entry Design

Study on the movement characteristics of the overlying stratum and surrounding rock control in ultraclose coal seams: A case study

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