• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2000.09a
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• pp.195-200
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• 2000

Numerical analysis using FLACSD has been conducted to estimate the stability of a large underground hall that is to be excavated in a mined area and constructed as an unit of a resort park. Numerical modelling is divided into two stages. The first stage is related to the analysis of the mechanical stability of the hall itself and the second to that of the influence of an adjacent mined cavity upon the hall. In the first stage, the stability of the hall is judged from the interpretation of numerical results in three respects: convergence of the unbalanced force of the model, occurrence of plastic zones and distribution of the displacement. In the second stage, variation of the stress state around the underground hall due to the existence of the cavity is compared to that in the case of the absence of the cavity. Through these analyses, it could be known that the large underground hall is not exposed to any mechanical problems and also not affected by the adjacent cavity. Key words : 3D numerical analysis, large underground cavern, stability analysis

• Tunnel and Underground Space
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• v.10 no.3
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• pp.441-446
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• 2000

Numerical analysis using FLAC3D has been conducted to estimate the stability of a large underground hall that is to be excavated in a mined area and constructed as an unit of a resort park. Numerical modelling is divided into two stages. The first stage is related to the analysis of the mechanical stability of the hall itself and the second to that of the influence of an adjacent mined cavity upon the hall. In the first stage, the stability of the hall is judged from the interpretation of numerical results in three respects: convergence of the unbalanced force of the model, occurrence of plastic zones and distribution of the displacement. In the second stage, variation of the stress state around the underground hall due to the existence of the cavity is compared to that in the case of the absence of the cavity. Through these analyses, it could be known that the large underground hall is not exposed to any mechanical problems and also not affected by the adjacent cavity.

• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.2
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• pp.135-141
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• 2002

This research has been conducted to investigate the influence of mined cavities on a tunnel to be constructed around a coal mine. The location and dimension of cavities were supposed by analysing synthetically geological structures and condition of coal beds as well as gangway map since there does not exist any map describing mined cavities. Detailed geological and geophygical survey have also been carried out for the purpose of understanding the geological structure and rock mass conditions. The two dimensional numerical analysis with FLAC has been performed on the geological sections reconstituted from the obtained information and the affects of mined cavities on the tunnel have been assessed.

• Tunnel and Underground Space
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• v.26 no.5
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• pp.418-430
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• 2016

In this study, experimental study on cement grout materials containing anti-washout admixtures or accelerators in grout column for reinforcement technology in groundwater-saturated mining cavity was conducted. As a result, the cement milk containing anti-washout admixtures was suitable for mixed aggregates, and the cement mortar containing anti-washout admixtures and the cement milk containing accelerators were suitable for crushed stone aggregate in terms of forming grout column. Especially, in the case of crushed stone aggregate injecting the cement milk containing accelerators, the diameter of the grout column was greatest and the void of the crushed stone aggregate was filled with grout materials. Therefore the case of crushed stone aggregate injecting the cement milk containing accelerators is considered for optimal grout materials and aggregate.

• Tunnel and Underground Space
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• v.28 no.5
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• pp.387-399
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• 2018

Mine reclamation project is closely related to human's past mining activities and the current human's living environment. It is a reason for the national management. In order to efficiently carry out mine reclamation projects, a precise investigation and analysis of the underground space of the abandoned mine is required. Korea MINE RECLAMATION Corp. is developing a practical technology that is effective in investigating and actually measuring underground cavities. MIRECO EYE system is an exploration equipment for 3D digitization and figuration of underground cavities. As combining a laser, sonar and image acquisition technology, it enables access to information about inaccessible underground cavities and effective management of subsidence risk of mined area. and currently it is also utilized for various purposes in related areas such as investigating urban sinkholes. This article is precise numerical and geometric information analysis obtained through MIRECO EYE system.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.3
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• pp.42-52
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• 1995

An UBET(Upper Bound Elemental Techniquel) program has been developed to analyze forging load, die-cavity filling and effective strain distribution for flashless non-axisymmetric forging. To analyze the process easily, it is suggested that the deforma- tion is divided into two different parts. Those are axisymmetric part in corner and plane- strain part in lateral. The total power consumption is minimized through combination of two deformation parts by building block method, form which the upper-bound forging load, the flow pattern, the grid pattern, the velocity distribution and the effective strain are deter- mined. To show the merit of flashless forging, the results of flashless and flash-forging processes are compared through theory and experiment. Experiments have been carried out with plasticine billets at room temperature. The theoretical predictions of the forging load and the flow pattern are in good agrement with the experimental results.