• Tunnel and Underground Space
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• v.23 no.4
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• pp.288-296
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• 2013

In this study, a total of 13 mines were finally selected as study subjects and field measurements were conducted. Thereafter, calculations of thermodynamic natural ventilation were attempted using spread sheets and solutions for natural ventilation of mine types with multiple vertical shafts were obtained. Based on the results, natural ventilation of each mine was quantified. In addition, changes in natural ventilation energy (NVE) and natural ventilation pressure (NVP) were estimated assuming mine deepening and the resultant values were applied to mine conditions to observe changes in flow rates. Natural ventilation pressure in domestic mines is generally calculated to be in a range of 5 Pa~300 Pa. Although NVP increases as the depth increases, resistance also increases. Therefore, as the depth increases, flow rates show a tendency of converging on a certain value because of the relationship between NVP and mine resistance. Natural ventilation using shafts with depth differences is effective up to depths of 200~300 m. However, flow rate change rates resulting from NVP are small at depths deeper than approximately 200~300 m. Therefore, if a mine is deepened over 300 m, NVP will become insufficient and thus additional pressure obtained through mechanical ventilation will be necessary.

• Tunnel and Underground Space
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• v.27 no.1
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• pp.12-25
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• 2017

In local underground mines heavily depending on the natural ventilation, ducted fan auxiliary ventilation system is strongly recommended instead of the total mine ventilation system requiring large capital and operating costs. Optimizing the installation of ducted fans in series in long large-opening mines is required to assure the economy and efficiency of the ventilation system. The two most critical design parameters for optimization are the wall separation distance and gap length between adjoining ducts. This study aims at deriving the optimal values for those two parameters concerning the economic and environmental aspects through the extensive CFD analysis, which minimizes pressure loss, leakage and entrainment of the contaminated air in the gap space. The ranges of the wall separation distance and gap length for study are selected by taking into consideration the existing recommendations and guidelines. The ultimate goal is to optimize the auxiliary ventilation system using ducted fans in series to provide a reliable and efficient solution to maintain clean and safe workplace environment in local long underground mines.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.267-272
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• 2005

Geophysical surveys were performed in three abandoned mines: Jangpoong, Kwangyang, Imchon. The main objectives of the researches include delineating the pathways of leachate from acid mine drainage(AMD), mapping buried rock wastes and tailings, detecting drainage pipes, and investigating the gallery and membrane, if they exist, Geophysical responses were well correlated with the results from water sample data(i.e., pH, EC, heavy metal contents, $SO_4^{-2}$). Main pathways of the leachate were successfully detected in electrical resistivity sections and self-potential(SP) profiles, whereas waste rocks, drainage pipes, and membranes were effectively located by incorporating seismic refraction, electrical resistivity and GPR methods.

• Tunnel and Underground Space
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• v.33 no.3
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• pp.126-140
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• 2023

In this study, the cause of subsidence in limestone mine was analyzed using a LiDAR-based geometry model. Using UAV and ground-based LiDAR systems, a precise geometry model was constructed for the subsidence surface and mine tunnel, and the results of on-site geological survey and rock mass classification were utilized. Through the geometry model, distribution of thickness of crown pillar and faults around the subsidence area, calculation of the volume of the subsidence area and subsidence deposit, and analysis of the subsidence surface inclination were conducted. Through these analyzes, the causes of ground subsidence were identified.

• Tunnel and Underground Space
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• v.33 no.2
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• pp.95-107
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• 2023

In this study, the effect of repeated traffic vibration on the long-term stability of mine openings is analyzed for re-utilization of abandoned mine galleries. The research mine in this study is an underground limestone mine which is developed by room-and-pillar mining method, and a dynamic numerical analysis is performed assuming that the research mine will be utilized as a logistics warehouse. The actual traffic vibration generated by the mining vehicles is measured directly, and its waveform is used as input data for dynamic numerical analysis, As a results of dynamic numerical analysis, after 20,000 repetitions of traffic vibration, the mine openings is analyzed to be stable, but an increase in the maximum principal stress and an additional area of plastic zone are observed in the analysis section. As shown in the changes of displacement, volumetric strain, and maximum principal stress which are measured at the mine opening walls. It is confirmed that if the repeated traffic vibration is continuously applied, the instability of the mine openings can be increased. Authors expect that the results of this study can be used as a reference for basic study on utilization of abandoned mine.

• Tunnel and Underground Space
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• v.28 no.4
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• pp.372-386
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• 2018

The air quality near the backfilled site area is significantly deteriorated during and even after the curing period of the backfill materials. Hazardous gases such as NH3 and CO2 may leak out prolongedly from the mined-out sites backfilled with the composite carbonate-based material; leakage can be observed at the underground working sites as well as on the surface. At operating mines, underground gas leakage will severely aggravate the workplace environment. The ventilation schemes should supply sufficient air to dilute the contaminated air, and control the toxic gas leakage and dispersion. This study shows the applicability of pressurization ventilation system to control gas leakage and dispersion at the backfilled underground mine site.

• Tunnel and Underground Space
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• v.29 no.5
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• pp.305-317
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• 2019

The RMR and Q-system for characterizing rock mass and drilling core, and for estimating the support and reinforcement measures in mine galleries, tunnels and caverns have been widely used by engineers. SMR has been widely used in the rock mass classification for rock slope, but Q-Slope has been introduced into slopes since 2015. In the last ten years, a modified Q-system called Q-slope has been tested by the many authors for application to the benches in open pit mines and excavated road rock slopes. The results have shown that a simple correlation exists between Q-slope values and the long-term stable and unsupported slope angles. Just as RMR and Q have been used together in a tunnel or underground space and complemented by comparison, Q-Slope can be used in parallel with SMR. This paper introduces how to use Q-Slope which has not been announced in Korea and application examples of Pasir open pit coal mine in Indonesia.

• Tunnel and Underground Space
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• v.25 no.2
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• pp.186-198
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• 2015

This paper aims for the ultimate goal to optimize the work place environment through assuring the optimal required ventilation rate based on the analysis of the airflow. The working environment is deteriorated due to a rise in temperature of a coal mine caused by increase of its depth and carriage tunnels. To improve the environment, the ventilation evaluation on J coal mine is carried out and the effect of a length of the tunnel on the temperature to enhance the ventilation efficiency in the subsurface is numerically analyzed. The analysis shows that J coal mine needs $17,831m^3/min$ for in-flow ventilation rate but the total input air flowrate is $16,474m^3/min$, $1,357m^3/min$ of in-flow ventilation rate shortage. The temperatures were predicted on the two developed models of J mine, and VnetPC that is a numerical program for the flowrate prediction. The result of the simulation notices the temperature in the case of developing all 4 areas of -425ML as a first model is predicted 29.30 at the main gangway 9X of C section and in the case of developing 3 areas of -425ML excepting A area as a second model, it is predicted 27.45 Celsius degrees.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.609-619
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• 2018

This study was carried out at a local limestone mine to analyze the ventilation efficiency of the shaft equipped with a main fan. The results show that its ventilation efficiency is clearly verified for the natural as well as the mechanical ventilation. The airflow rate of $11.7m^3/s$ was induced by the natural ventilation force and the maximum quantity is almost same as the airflow rate estimated by monitoring the average temperatures in the upcast and downcast air columns. Meanwhile, the airflow rate exhausted by the main fan through the shaft was $20.3{\sim}24.8m^3/s$; variation of the quantity was caused by the upward shift of the mine ventilation characteristic curve due to the frequent movement of the equipment. This indicates efforts are required to reduce the ventilation resistance and raise the quantity supplied by the main fan. The turbulent diffusion coefficients along the 1912 m long airway from the portal to the shaft bottom was estimated to be $15m^2/s$ and $18m^2/s$. Since these higher coefficients imply that contaminants will be dispersed at a faster velocity than the airflow, prompt exhaust method should be planned for the effective air quality control. The ventilation shaft and main fan are definitely what local limestone mines inevitably need for better working environment and sustainable development.

• Tunnel and Underground Space
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• v.14 no.2
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• pp.86-96
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• 2004

Rock mass classification methods such as RMR, Q system and GSl have been widely adopted with certain modifications for the design of mine openings. The GSI system is the only rock mass classification system that is related to Mohr-Coulomb and Hoek-Brown strength parameters and gives a simple method to calculate the engineering properties of rock masses which can be useful input parameters for a numerical analysis. A detailed surveying for GSI mapping as well as far calculating RMR values was undertaken at Daesung and Pyunghae underground limestone mining sites. RQD values were determined for row locations in these two mining sites. Based on GSI values and intact rock strength properties, the rock mass strength modulus of elasticity as well as the Mohr-Coulomb strength parameter c$_{m}$ and $\phi$$_{m}$ were determined. GSI and RMR are correlated.