A case study of multi-seam coal mine entry stability analysis with strength reduction method

Tulu, Ihsan Berk; Esterhuizen, G.S.; Klemetti, Ted; Murphy, Michael M.; Sumner, J. T.; Sloan, Michael

doi:10.1016/j.ijmst.2015.12.003

Cited by 36 publications

(23 citation statements)

References 2 publications

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“…It is widely used in civil and mining engineering applications (e.g. Tulu et al, 2016;Sears et al, 2018). Its application to geological systems across a range of scales can be found in the literature (e.g.…”

Section: Modelling Methodologymentioning

confidence: 99%

Numerical modelling of coal seam depressurization during coal seam gas production and its effect on the geomechanical stability of faults and coal beds

Zhang

Underschultz

Langhi

et al. 2018

International Journal of Coal Geology

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Section: Modelling Methodologymentioning

confidence: 99%

Numerical modelling of coal seam depressurization during coal seam gas production and its effect on the geomechanical stability of faults and coal beds

Zhang

Underschultz

Langhi

et al. 2018

International Journal of Coal Geology

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“…This paper focuses on mining in the Kellioka Seam, located below workings in the Owl and Darby coal beds. The majority of the mining layout and geotechnical parameters for the study areas were published in previous papers [ 1 , 2 ]. Two particular parameters to be expanded upon in this paper are the multiple-seam mining geometry and the variable geology encountered in these four panels.…”

Section: Mining and Geotechnical Parametersmentioning

confidence: 99%

“…During an evaluation of unexpected conditions experienced at an eastern Kentucky room and pillar retreat mine that was conducted as part of a NIOSH research effort, it became evident that several factors associated with stress redistribution were involved. The initial efforts and results were published in the past two International Conference on Ground Control in Mining (ICGCM) proceedings by Tulu et al [ 1 , 2 ]. These two publications concluded that topographical changes and multiple-seam interactions were the cause of the unexpected conditions leading to the difficulties experienced in panels L6 and L4.…”

Section: Introductionmentioning

confidence: 99%

Design concerns of room and pillar retreat panels

Klemetti

Sears

Tulu

2017

International Journal of Mining Science and Technology

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Why do some room and pillar retreat panels encounter abnormal conditions? What factors deserve the most consideration during the planning and execution phases of mining and what can be done to mitigate those abnormal conditions when they are encountered? To help answer these questions, and to determine some of the relevant factors influencing the conditions of room and pillar (R & P) retreat mining entries, four consecutive R & P retreat panels were evaluated. This evaluation was intended to reinforce the influence of topographic changes, depth of cover, multiple-seam interactions, geological conditions, and mining geometry. This paper details observations were made in four consecutive R & P retreat panels and the data were collected from an instrumentation site during retreat mining. The primary focus was on the differences observed among the four panels and within the panels themselves. The instrumentation study was initially planned to evaluate the interactions between primary and secondary support, but produced rather interesting results relating to the loading encountered under the current mining conditions. In addition to the observation and instrumentation, numerical modeling was performed to evaluate the stress conditions. Both the LaModel 3.0 and Rocscience Phase 2 programs were used to evaluate these four panels. The results of both models indicated a drastic reduction in the vertical stresses experienced in these panels due to the full extraction mining in overlying seams when compared to the full overburden load. Both models showed a higher level of stress associated with the outside entries of the panels. These results agree quite well with the observations and instrumentation studies performed at the mine. These efforts provided two overarching conclusions concerning R & P retreat mine planning and execution. The first was that there are four areas that should not be overlooked during R & P retreat mining: topographic relief, multiple-seam stress relief, stress concentrations near the gob edge, and geologic changes in the immediate roof. The second is that in order to successfully retreat an R & P panel, a three-phased approach to the design and analysis of the panel should be conducted: the planning phase, evaluation phase, and monitoring phase.

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“…Coal is an unusual porous material, which has fissures, low intensity strength, heterogeneous texture, and permeability distinguishing it from regular porous materials [6,7]. Gas within the coal seam can strongly affect coal strength, deformation, and fracture propagation, and other mechanical properties [8][9][10]. In underground coal mines, gas is stored in a coal seam mainly in absorbed form or free state.…”

Section: Introductionmentioning

confidence: 99%

Numerical Assessment of the Influences of Gas Pressure on Coal Burst Liability

Zhao

Kaunda

2018

Energies

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When coal mines exploit deep seams with high-gas content, risks are encountered due to the additional high likelihood of rock bursting potential problems. The bursts of coal pillars usually lead to severe fatalities, injuries, and destruction of property, including impeding access to active mine workings underground. The danger exists given that conditions in the already highly brittle coal material can be exacerbated by high stress and high gas pressure conditions. It is thus critical to develop methods that improve current understanding about bursting liability, and techniques to forecast or prevent coal bursting in underground coal mines. This study uses field data from a deep coal mine, and numerical modeling to investigate the effects of gas pressure and mechanical compressive stresses on coal bursting liability in high gas content coal seams. The bursting energy index is adopted to determine the coal bursting liability under high gas pressure conditions. The adopted methodology uses a two-staged approach comprising investigating the influence of gas pressure on the bursting liability of coal pillar, and the influence of the gas pressure on the resulting pillar failure mode. Based on numerical simulations of coal pillars, correlations are observed between the magnitudes of gas pressures and the bursting energy index. Irrespective of pillar size, failure time is shortest when the gas pressure achieves a threshold value between 50 kPa to 70 kPa. At 50 kPa, the value of the BEI increases by 50% going from the 4 m pillar to the 6 m pillar. The value of the BEI increases by 43% going from the 6 m high pillar to the 8 m high pillar at 50 kPa. When pillars fail there is a degree of stress relief leading to a reduction in bursting liability. The results suggest that before 50 kPa, pillar failure is largely due to mechanical loading. After 50 kPa, pillar failure is largely due to excessive gas pressures.

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A case study of multi-seam coal mine entry stability analysis with strength reduction method

Cited by 36 publications

References 2 publications

Numerical modelling of coal seam depressurization during coal seam gas production and its effect on the geomechanical stability of faults and coal beds

Numerical modelling of coal seam depressurization during coal seam gas production and its effect on the geomechanical stability of faults and coal beds

Design concerns of room and pillar retreat panels

Numerical Assessment of the Influences of Gas Pressure on Coal Burst Liability

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