Study on Pillar Stability of Wongawilli Mining Area in Shallow Close Distance Coal Seams

Zhu, Weibing; Xu, Jialin; Kong, Xiang Song; Xuan, Dayang; Qin, Wei

doi:10.1016/j.proeps.2009.09.038

Cited by 19 publications

(13 citation statements)

References 2 publications

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“…, ) is the caving step distance of strata , m; , , and ℎ are the rock average bulk density, average elastic modulus, and thickness of rock strata of strata , kN/m 3 , MPa, and m, respectively; overburden and ℎ overburden are the average bulk density of bedrocks and overburden as well as overburden thickness, kN/m 3 and m, respectively. Equation (1) indicates that the loading key strata are determined according to the load step and the load [7].…”

Section: Movement Forms Of Overlying Strata and Formation Mechanism Omentioning

confidence: 99%

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Formation Mechanism and Reduction Technology of Mining-Induced Fissures in Shallow Thick Coal Seam Mining

2017

Shock and Vibration

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Surface mining-induced fissures formed in shallow coal seam mining have serious impact on safety mining and water resources protection. This paper proposes a novel approach to study the formation mechanism and dynamic development of surface mininginduced fissures in shallow coal seam mining. This approach combines field tests, theoretical analysis, and numerical simulations based on the geological condition of shallow coal seam mining in Chuancao Gedan Coal Mine. Two typical surface mininginduced fissures, step-type fissures and collapse-type fissures, are generated in shallow coal seam mining. The fissures with large vertical throw or horizontal opening severely impact water resource protection and surface ecological environment. Surface mininginduced fissures are generated periodically and changed dynamically with the advancing of working face. The vertical throw and horizontal opening of surface fissures are changed dynamically with the movement of loading key strata. The movement forms of loading key strata determine the morphological development of surface fissures. Downward sliding movement of broken rocks causes step-type fissures, while downward rotation movement leads to collapse-type fissures. The degree of the downward sliding and rotation of broken rocks determines the vertical throw and horizontal opening of surface fissures. This paper proposes mining technologies to reduce damaging ground fissures in shallow coal seam mining and analyzes their control effects.

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Section: Movement Forms Of Overlying Strata and Formation Mechanism Omentioning

confidence: 99%

“…With coal exploitation focus transferring to the Western China, more and more attention is paid to safety mining [1,2]. Mining area in Western China generally has characteristics of shallow burial depth, large coal reserves, and fragile ecological environment.…”

Section: Introductionmentioning

confidence: 99%

Formation Mechanism and Reduction Technology of Mining-Induced Fissures in Shallow Thick Coal Seam Mining

2017

Shock and Vibration

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“…Zhang et al [25] incorporated geotechnical considerations for concurrent pillar recovery in extremely close coal seams, where mining sequence, panel layout, and pillar size were considered. Based on the observations of surface subsidence and three-dimensional simulations, Yu et al [26] and Zhu et al [27] studied the relationship between upper coal pillar and lower working face. Based on the floor failure mechanics model, Zhang et al [28] proposed a new method to monitor floor failure depth and successfully applied it to the Caocun coal mine in China.…”

Section: Introductionmentioning

confidence: 99%

Study on Law of Overlying Strata Breakage and Migration in Downward Mining of Extremely Close Coal Seams by Physical Similarity Simulation

2020

Advances in Civil Engineering

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Extremely close coal seam groups are widely distributed in China, and the main mining method is downward mining. In the downward mining process of extremely close coal seam groups, the violent movement of overlying strata will cause the redistribution of surrounding rock stress. It not only produces stress concentration on the pillar but also causes the roof of the lower coal seam to be broken and difficulty in maintaining the mining roadway. In this study, the physical similitude modeling method and field observations were used to study the breakage and migration law of overlying strata in the downward mining of extremely close coal seams. Results show that in the process of mining upper coal seam, the first weighting step of the main roof is 37.5 m and the periodic weighting step is 12.5 m. The occurrence of strata separation is beneficial to the prediction of roof weighting. When the working face advances to 25 m, the rock stratum approximating a parallelogram of height 5 m does not collapse, and the working face is relatively dangerous. When mining the lower coal seam, the overall pressure of the working face is large, but the periodic weighting of the working face is not obvious. The first collapse step of the immediate roof is 15 m. When mining the upper and lower coal seams, the subsidence of the monitoring point increases significantly at 17.5 and 15 m, respectively. The roof collapse of the lower coal seam occurs 2.5 m ahead of that of the upper coal seam. The hydraulic value of the support, roof fall height, and sloughing depth in the entire working face reach the maximum at the coal pillar, and the extreme points at the coal pillar are relatively concentrated. This research provides some guidance for the safe and efficient mining of extremely close coal seams in the future.

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“…Hence, the longwall face or gateroad in the lower coal seam may be located in the lower part of the residual coal pillars in the upper coal seam. Because of the small distance between the coal seams (<20 m), the concentrated stress that is transmitted by the residual coal pillars in the upper coal seam will inevitably result in difficulties with longwall face mining and gateroad support in the lower coal seam …”

Section: Introductionmentioning

confidence: 99%

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

Shang

Ning

et al. 2019

Energy Science & Engineering

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The Gaojialiang Coal Mine in Inner Mongolia in China was used as an example to investigate the process of chain pillar and gateroad failure in the lower coal seam under the effect of an irregular residual coal pillar in the upper close‐distance coal seam. The results indicated that after the longwall face in the lower coal seam retreated through the area under the large irregular residual coal pillar in the upper coal seam, the bearing area of the residual coal pillar decreased and the roof pressure continuously concentrated in the elastic core area of the residual coal pillar. Isolated triangular slab rock was formed above the triangular residual coal pillar, and the weight of the overlying strata was transferred downward through the triangular slab rock. When the chain pillar under the residual coal pillar was destroyed due to loading that exceeded its carrying capacity, the upper triangular slab rock rotated and sank, which resulted in the intensification of the concentrated stress in the solid rib of the gateroad in the lower coal seam. Based on the analysis, it is suggested that in the design of a longwall system, a gateroad under an isolated residual coal pillar in the upper coal seam should be avoided when mining in close‐distance coal seams.

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Study on Pillar Stability of Wongawilli Mining Area in Shallow Close Distance Coal Seams

Cited by 19 publications

References 2 publications

Formation Mechanism and Reduction Technology of Mining-Induced Fissures in Shallow Thick Coal Seam Mining

Formation Mechanism and Reduction Technology of Mining-Induced Fissures in Shallow Thick Coal Seam Mining

Study on Law of Overlying Strata Breakage and Migration in Downward Mining of Extremely Close Coal Seams by Physical Similarity Simulation

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

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