Coal Pillar Strength Formula in Indonesian coal mines

Putri, Ratih Hardini Kusuma

doi:10.31284/j.jemt.2020.v1i1.1147

Cited by 4 publications

(5 citation statements)

References 4 publications

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“…As the pillar width increased, the safety factor varied greatly depending on the pillar strength equation selected. Putri conducted a study on appropriate pillar strength equations for Indonesian coal mines and stated that Obert-Duvall's proposed equation is suitable for Indonesian coal mines 16 . Although the coal mines studied in this study differ from those studied in Putri, both are Indonesian mines and the geological conditions are assumed to be similar.…”

Section: Pillar Design Based On Safety Factormentioning

confidence: 99%

“…Several studies have been conducted on the stability of longwall face and gate entry in the coal mines studied in this research 14,15 . Putri conducted a study on appropriate pillar strength equations based on data from airlaya's coal seam in Indonesia and stated that the Bieniawski equation and Obert-Duvall equation were appropriate 16 . However, not only the pillar stability but also the influence on the longwall coal face should be considered in Indonesia because the strength of the surrounding rock is weaker than the strength of the coal seam in shallow depth.…”

Section: Introductionmentioning

confidence: 99%

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Study on Pillar Design for Longwall Mining under Weak Immediate Roof and Floor Strata in Indonesia

Hashikawa

Mao

Sasaoka

et al. 2022

Preprint

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More than 99% of coal mining in Indonesia is open-pit mining. Nowadays, the adoption of the underground coal mining method is discussed to extend coal production due to the increasing demand for coal. However, the geological conditions in Indonesia are very weak compared to the U.S., Europe, and Australia where the longwall mining method is often applied. Especially, the mechanical properties of immediate roof/floor in shallow depth are weaker than those of coal. Therefore, the control measures to maintain the stability around the developing area should be discussed for the safe longwall mining operation. This study discusses the design of safety pillar width in longwall mining under weak geological conditions by using FLAC3D. It is found that the conventional equations for the determination of the pillar width, Obert-Duvall, Holland-Gaddy, and Bieniawski equations, can be adopted to maintain the stability of the pillar itself, but are not suitable for the stability of the longwall face because of the influence on the neighboring panel extraction. Additionally, the increase of the pillar width can significantly reduce the fracture zone around the longwall face while increasing the setting load of the shield support can slightly improve the stability. The pillar design needs to be considered not only the pillar strength but also the stability of the longwall face under the weak geological conditions in Indonesia.

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Section: Pillar Design Based On Safety Factormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study on Pillar Design for Longwall Mining under Weak Immediate Roof and Floor Strata in Indonesia

Hashikawa

Mao

Sasaoka

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…Putri conducted a study on appropriate pillar strength equations based on data from the Air Laya coal mine in Indonesia. The study stated that the Bieniawski equation and Obert-Duvall equation were appropriate [16]. However, not only the pillar stability but also the influence on the longwall coal face should be considered in Indonesia because the strength of the surrounding rock is weaker than the strength of the coal seam in shallow depths.…”

Section: Introductionmentioning

confidence: 99%

“…As the pillar width increased, the safety factor varied greatly depending on the pillar strength equation selected. Putri conducted a study on appropriate pillar strength equations for Indonesian coal mines and stated that Obert-Duvall's proposed equation is suitable for Indonesian coal mines [16]. Although the coal mines studied in this study differ from those studied by Putri, both are Indonesian mines, and the geological conditions are assumed to be similar.…”

mentioning

confidence: 98%

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Numerical Simulation on Pillar Design for Longwall Mining under Weak Immediate Roof and Floor Strata in Indonesia

et al. 2022

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In Indonesia, the adoption of the underground coal mining method is discussed to extend coal production. However, the geological conditions in Indonesia are very weak. In particular, the mechanical properties of the immediate roof/floor in shallow depths are weaker than those of coal. Therefore, the control measures to maintain stability around the developing area should be discussed for safe longwall mining operations. This study discusses the design of safety pillar width in longwall mining under weak geological conditions by using FLAC3D. The study reveals that the conventional equations for the determination of the pillar width, i.e., Obert-Duvall, Holland-Gaddy, and Bieniawski equations, can be adopted to maintain the stability of the pillar itself but are not suitable for the stability of the longwall face because of the influence of the extracted neighboring panels. Additionally, the increase of the pillar width can significantly reduce the fracture zone around the longwall face. Also, increasing the setting load of the powered support can slightly improve the stability. In the pillar design, both the pillar strength and the stability of the longwall face under weak geological conditions need to be considered.

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Ground control by L-shaped cemented paste backfilling technology in underground coal seam mining: a case study

Guo,

Tan

et al. 2024

Geomech. Geophys. Geo-energ. Geo-resour.

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Traditional cemented paste backfilling continues to face the shortcomings such as paste leakage, poor adaptability to geological structures and insufficient roof-contact. To solve the limitations, a novel L-shaped cemented paste backfilling (LCPB) technology was proposed in this study. It is to set L-shaped filling zones and partition zones in the goaf to perform interval and multiple filling. A mechanical model was established to calculate backfilling body strength, widths of L-shaped filling zones and partition zones and backfilled ratio and etc. The results of a case study showed that: (1) The LCPB mining has a high backfilled ratio, without prominent ground pressure. The maximum values of roof-to-floor convergence of the working face and roadway were 58 mm and 259 mm, respectively. It could effectively control the deformation of surrounding rock and achieve roadway retention. (2) When the floor strata were intact, the maximum floor damage depth was less than 4 m, and the floor near the fault was 10–12 m. The secondary lift height of the confined water was about 5 m near the fault. The LCPB mining allows for safety mining above a confined aquifer. (3) The maximum surface inclination and curvature were 1.75 mm/m and 0.06 mm/m2, respectively. The draw angle was 11.3°, and the subsidence factor was 0.085. The ground surface deformation was reduced to be less than that allowed in the first level of the building damage (inclination and curvature of 3 mm/m and 0.2 mm/m2, respectively).

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Coal Pillar Strength Formula in Indonesian coal mines

Cited by 4 publications

References 4 publications

Study on Pillar Design for Longwall Mining under Weak Immediate Roof and Floor Strata in Indonesia

Study on Pillar Design for Longwall Mining under Weak Immediate Roof and Floor Strata in Indonesia

Numerical Simulation on Pillar Design for Longwall Mining under Weak Immediate Roof and Floor Strata in Indonesia

Ground control by L-shaped cemented paste backfilling technology in underground coal seam mining: a case study

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