Optimum Chain Pillar Design at the Deepest Multi-Seam Longwall Workings in India

Ghosh, Nilabjendu; Agrawal, Harshit; Singh, Satyendra Kumar; Banerjee, G.

doi:10.1007/s42461-019-00138-z

Cited by 13 publications

(7 citation statements)

References 17 publications

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“…Anchor rods are used to support the surrounding rock and their stress characteristics and influence on the plastic zone are analyzed under these conditions using the NBSS model [ 39 ]. We adopted full-length bonded anchor rods with a diameter of 18 mm, length of 2.2 m, and spacing of 1.0 m as the support structure.…”

Section: Nbss Creep Damage Modelmentioning

confidence: 99%

Analysis and numerical calculation of a coupled creep and strain-softening model for soft rock tunnels

Jianjun

Yao

et al. 2021

PLoS ONE

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Proper mechanical model selection is critical in tunnel support design and stability analysis, especially to reflect the creep and strain-softening behavior of soft rock. We present a coupled nonlinear Burgers strain-softening (NBSS) model and numerical calculation method to investigate the coupled effects of creep and strain-softening of soft rock tunnels. The nonlinear elastic-viscous model is used to simulate the steady creep behavior of mudstone, and the nonlinear viscoplastic strain-softening model is used to simulate the accelerated creep behavior and post-peak strength attenuation behavior. The experimental results show that the viscoplastic parameters and post-peak softening parameters of mudstone are highly sensitive to confining pressure and exhibit nonlinear characteristics. The accelerated creep curve obtained by the numerical calculation is consistent with the experiments, which verifies the model reliability. We use the NBSS and nonlinear Burgers Mohr-Coulomb (NBMC) models to calculate the plastic zone distribution characteristics and deformation law. The distribution of the plastic zone calculated by the NBSS model is larger with more localized fractures. The NBSS model is useful for studying the evolution of stress and displacement fields of complex surrounding rock mass, which provides important theoretical guidelines for the support design and stability analysis of soft rock tunnel engineering.

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Section: Nbss Creep Damage Modelmentioning

confidence: 99%

Analysis and numerical calculation of a coupled creep and strain-softening model for soft rock tunnels

Jianjun

Yao

et al. 2021

PLoS ONE

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“…As a result, they found that the support schemes could effectively suppress the deformation of the surrounding rock mass by introducing support schemes at the goaf-side entry driving 7 . Besides, Ghosh et al conducted an analysis of chain pillars in multi-seam longwall mining panels in the coal mines in India 8 . However, these studies were conducted on coal mines with relatively high-strength geotechnical conditions.…”

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

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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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“…Due to the disturbance of upper coal seam mining, the roof of the roadway is destroyed before the lower coal seam is mining, resulting in changes in the roof structure [1][2][3] and stress environment of the lower coal seam mining area [4,5]. In addition, the roadway surrounding rock is disturbed and destroyed repeatedly while mining the lower coal seam, which can easily lead to the instability and serious destruction of the roadway surrounding rock [6,7]. At present, the processes of mining and excavating have become unsmooth for most coal mines, the roadway support technology is unfeasible, there is a certain degree of convergence in the vertical and horizontal directions of the roadway [8], and significant roadway maintenance is required in the later stage of working face mining [9,10], which greatly affects the speed, safety, and efficiency of roadway excavation.…”

Section: Introductionmentioning

confidence: 99%

Instability Control of Roadway Surrounding Rock in Close-Distance Coal Seam Groups under Repeated Mining

et al. 2021

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In order to solve the problems of roadway stability and easy instability under repeated mining of close-distance coal seam groups, the mechanism and control technology of surrounding rock instability under repeated mining were studied via indoor testing, field testing, physical similarity simulation experiment, and numerical simulation. The results show that the surrounding rock of roadway has low strength, low bearing capacity, and poor self-stabilization ability, and it is vulnerable to engineering disturbances and fragmentation. Affected by the disturbance under repeated mining, the roadway surrounding rock cracks are developed and the sensitivity is strong, and it is prone to large-scale loose and destroyed. The location of the roadway is unreasonable, and the maximum principal stress of the roadway is 3.1 times of the minimum principal stress, which is quite different. Thus, under a large horizontal stress, the surrounding rock undergoes long-range expansion deformation. On the basis of this research, the direction and emphasis of stability control of roadway surrounding rock under repeated mining of coal seam groups in close-distance are shown. A repair scheme (i.e., long bolt + high-strength anchor cable + U-shaped steel + grouting) is proposed, and reduces the risk of roadway instability.

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Optimum Chain Pillar Design at the Deepest Multi-Seam Longwall Workings in India

Cited by 13 publications

References 17 publications

Analysis and numerical calculation of a coupled creep and strain-softening model for soft rock tunnels

Analysis and numerical calculation of a coupled creep and strain-softening model for soft rock tunnels

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

Instability Control of Roadway Surrounding Rock in Close-Distance Coal Seam Groups under Repeated Mining

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