Major projects and research topics in the field of rock mechanics are analyzed to obtain the foll... more Major projects and research topics in the field of rock mechanics are analyzed to obtain the following results: Rock mechanics deals with the behavior of deformation, failure and displacement of the rock and rock mass on the basis of geological basics. Discontinuities in the rock mass are the most important parameters to control the behavior of rock mass around underground openings. The objective of site investigation and testing is to determine the strength properties of the rock mass and the in situ stress regime. Specimens for laboratory and in situ tests are to be selected in order that the results of the tests give the representative properties oi the rock mass of the site in question. The result of a numerical model would be better evaluated not quantitatively but qualitatively. The displacement behavior of the rock mass has to be monitored properly for the NATM (New Austrian Tunneling Method) principles. The stability of rock slope is to be evaluated preferably by back analysis with strength parameters, such as cohesion and friction angle.
The focus of rock related research in Korea is seen as application oriented in the last 25 years,... more The focus of rock related research in Korea is seen as application oriented in the last 25 years, resulting from the growing demand of infrastructure and underground space. The future may see more sophisticated techniques such as advanced joint and fracture modelling, discontinuum analysis, accurate monitoring techniques and efficient rock supporting to cope up with this continuing demand. New challenging issues are expected to appear for various problems related to subsurface storage of LNG(liquefied natural gas), high level radioactive repositories, subsurface sequestration of C02, etc. Rock mechanics discipline shall be oriented toward ensuring health of the infrastructures and safeguarding the environment.
A new underground LNG storage concept in the rock mass has been developed by combining undergroun... more A new underground LNG storage concept in the rock mass has been developed by combining underground cavern construction and new ice-ring harrier technologies with the conventional cryogenic insulation system. Technical feasibility of the storage system has been verified through construction and operation of the pilot storage cavern and a full-scale project is expected to start in the near future. One of the most important issues in the LNG storage system is the operational efficiency of the storage to minimize heat loss during a long period of operation due to the cryogenic heat transfer. This paper presents several important results of heat transfer and coupled hydro-thermal analyses by a finite element code Temp/W and Seep/W. A series of heat transfer analyses for full-scale caverns were performed to determine design parameters such as boil-off gas ratio (BOR), insulation thickness and pillar width. The result of the coupled hydro-mechanical analysis showed that BOR for underground storage system remains at about 0.04 %/day during the early stage of the operation. This value could be even much lower when the discontinuities in the rock masses are taken into consideration.
This symposium is aimed to promote collaboration and meetings between scholars, professional engi... more This symposium is aimed to promote collaboration and meetings between scholars, professional engineers and the industrial demands of the Asian region, where projects for rock mechanics are very flourishing. Lots of new techniques, theories and case histories on tunnels, underground chambers, mine stopes, nuclear waste disposal repositories and other underground spaces are introduced. The 160 technical papers are focused on the environmental and safety aspects in the design and construction of underground rock structures. Topics: Heat, gas and water flow, and contaminant transport problems in waste disposal; Heat, gas and water flow, and contaminant transport problems in caverns and tunnels; Blasting and machine excavation; Subsidence and ground control; Questions and measures for safety in the design and construction of tunnels; Questions and measures for safety in the design and construction of caverns and openings; Modelling techniques for safety evaluation: Rock characterization; Evaluation of rock mass properties; Simulation of the coupled behavior; Monitoring & interpretation Back analysis and others; Slope stability and landslides.
This study deals with the case that was the field application of the microseismic monitoring tech... more This study deals with the case that was the field application of the microseismic monitoring techniques for the stability monitoring in a domestic mine. The usefulness and limitations of the microseismic techniques were examined through analyzing the microseismic monitored data. The target limestone mine adopted a hybrid room-and-pillar mining method to improve the extraction ratio. The accelerometers were installed in each vertical pillar within the test bed which has the horizontal cross-section 50 m × 50 m. The measured signals were divided into 4 types; blasting induced signal, drilling induced signal, damage induced signal, and electric noise. The stability analysis was performed based on the measured damage induced signals. After the blasting in the mining section close to the test bed, the damage of the pillar was increased and rockfall near the test bed could be estimated from monitored microseismic data. It was possible to assess the pillar stability from the changes of daily monitored data and the proposed safety criteria from the accumulated monitored data. However, there was a difficulty to determine the 3D microseismic source positions due to the 2D local sensor arrays. Also, it was needed to use real-time monitoring methods in domestic mines. By complementing the problems encountered in the mine application and comparing microseismic monitored data with mining operations, the microseismic monitoring technique can be used as a better safety method.
An experimental and numerical study was carried out to study solidliquid mixture upward hydraulic... more An experimental and numerical study was carried out to study solidliquid mixture upward hydraulic transport of solid particles in vertical and inclined annuli with rotating inner cylinder. Lift forces acting on a fluidized particle plays a central role in many importance applications, such as the removal of drill cuttings in horizontal drill holes, sand transport in fractured reservoirs, sediment transport and cleaning of particles from surfaces. Effect of annulus inclination and drill pipe rotation on the carrying capacity of drilling mud and pressure drop in a slim hole annulus have been measured for fully developed flows of water and of aqueous solutions of sodium carboxymethyl cellulose (CMC), respectively. For water and CMC solution the higher the concentration of the solid particles is, the larger the pressure gradients become.
It is difficult to solve problems regarding the adjustment on demand and supply of liquefied natu... more It is difficult to solve problems regarding the adjustment on demand and supply of liquefied natural gas (LNG) due to seasonal variations of domestic demand of LNG, discordance among import pattern, limits of storage facilities, and so on. Therefore, it is very important to secure large LNG storage facilities and to stabilize LNG supply management on a long term basis. A new concept of storing LNG in a lined rock cavern with containment system has been developed by Geostock, SKEC and SN Technigaz with the help of KIGAM. To demonstrate the feasibility of this concept and validate numerical modelling and calculations, a pilot plant was constructed at KIGAM in Daejeon Science Complex in 2003, which had been under operation for storing LN2 (Boiling Temperature:-196°C) since January 2004, and now been decommissioned. The objective of this study is to examine the realscale applicability of a lined underground rock storage system, which has been verified by a successful operation of the Daejeon LNG pilot plant. The new technology has many advantages of better economy, safety and environment protection, for above-ground and in-ground storage systems. The results of this study may promote the first ever real scale underground LNG storage system in a rock cavern.
Journal of the Korean Society of Mineral and Energy Resources Engineers, Apr 1, 2013
The physical properties and coagulation of suspended solids in a settling pond designed to contro... more The physical properties and coagulation of suspended solids in a settling pond designed to control flying rock dust during screening of limestone ores in O limestone mine were evaluated. The neutralization capacity of settled sludge was also studied. Turbidity at the inlet and outlet of the settling pond was measured as 2,264 and 1,228 NTU, respectively. The later was still considered to be a high level of turbidity just before recycling. The particle size (d(0.5)) of suspended solids in the settling pond ranged 5.1 to 10.1 μm. Jar tests showed improved coagulation of suspended solids at a pH 3 to 5 as concentration of coagulant, increased from 1 to 10 mg/L and as period of mixing increased. Neutralization evaluation results revealed that fine sludge <1 mm in size from the settling pond increased the pH of acid mine drainage to pH 6 and could remove dissolved Al and Fe within 10 minutes.
This paper reports the background information and the initial results obtained from the pilot und... more This paper reports the background information and the initial results obtained from the pilot underground LNG (liquefied natural gas) storage cavern in Korea, where all natural gas is stored in the condition of liquid phase. Many attempts have been made in the past to store LNG underground in unlined containment, though without success. A new concept for storing LNG in a lined rock cavern has been developed to provide a safe and cost-effective solution. It consists of protecting the host rock against the extremely low temperature and providing a liquid and gas tight liner. One of the most significant problems related to underground storage of cryogenic material is the need to prevent the leakage of liquid and gas from the containment system to the rock mass caused by tensile failures due to shrinkage of the rock mass around the caverns. In order to verify the technical feasibility of this storage concept, a pilot plant was constructed for storing Liquefied Nitrogen and has been in operation since January 2004, though has now been decommissioned. The overall monitored results from the pilot operations confirmed that the construction and operation of underground LNG storage in lined rock caverns is technically feasible for a rock engineering point of view. The results of this study may promote the first ever real scale underground LNG storage system in a rock cavern in the world.
Major projects and research topics in the field of rock mechanics are analyzed to obtain the foll... more Major projects and research topics in the field of rock mechanics are analyzed to obtain the following results: Rock mechanics deals with the behavior of deformation, failure and displacement of the rock and rock mass on the basis of geological basics. Discontinuities in the rock mass are the most important parameters to control the behavior of rock mass around underground openings. The objective of site investigation and testing is to determine the strength properties of the rock mass and the in situ stress regime. Specimens for laboratory and in situ tests are to be selected in order that the results of the tests give the representative properties oi the rock mass of the site in question. The result of a numerical model would be better evaluated not quantitatively but qualitatively. The displacement behavior of the rock mass has to be monitored properly for the NATM (New Austrian Tunneling Method) principles. The stability of rock slope is to be evaluated preferably by back analysis with strength parameters, such as cohesion and friction angle.
The focus of rock related research in Korea is seen as application oriented in the last 25 years,... more The focus of rock related research in Korea is seen as application oriented in the last 25 years, resulting from the growing demand of infrastructure and underground space. The future may see more sophisticated techniques such as advanced joint and fracture modelling, discontinuum analysis, accurate monitoring techniques and efficient rock supporting to cope up with this continuing demand. New challenging issues are expected to appear for various problems related to subsurface storage of LNG(liquefied natural gas), high level radioactive repositories, subsurface sequestration of C02, etc. Rock mechanics discipline shall be oriented toward ensuring health of the infrastructures and safeguarding the environment.
A new underground LNG storage concept in the rock mass has been developed by combining undergroun... more A new underground LNG storage concept in the rock mass has been developed by combining underground cavern construction and new ice-ring harrier technologies with the conventional cryogenic insulation system. Technical feasibility of the storage system has been verified through construction and operation of the pilot storage cavern and a full-scale project is expected to start in the near future. One of the most important issues in the LNG storage system is the operational efficiency of the storage to minimize heat loss during a long period of operation due to the cryogenic heat transfer. This paper presents several important results of heat transfer and coupled hydro-thermal analyses by a finite element code Temp/W and Seep/W. A series of heat transfer analyses for full-scale caverns were performed to determine design parameters such as boil-off gas ratio (BOR), insulation thickness and pillar width. The result of the coupled hydro-mechanical analysis showed that BOR for underground storage system remains at about 0.04 %/day during the early stage of the operation. This value could be even much lower when the discontinuities in the rock masses are taken into consideration.
This symposium is aimed to promote collaboration and meetings between scholars, professional engi... more This symposium is aimed to promote collaboration and meetings between scholars, professional engineers and the industrial demands of the Asian region, where projects for rock mechanics are very flourishing. Lots of new techniques, theories and case histories on tunnels, underground chambers, mine stopes, nuclear waste disposal repositories and other underground spaces are introduced. The 160 technical papers are focused on the environmental and safety aspects in the design and construction of underground rock structures. Topics: Heat, gas and water flow, and contaminant transport problems in waste disposal; Heat, gas and water flow, and contaminant transport problems in caverns and tunnels; Blasting and machine excavation; Subsidence and ground control; Questions and measures for safety in the design and construction of tunnels; Questions and measures for safety in the design and construction of caverns and openings; Modelling techniques for safety evaluation: Rock characterization; Evaluation of rock mass properties; Simulation of the coupled behavior; Monitoring & interpretation Back analysis and others; Slope stability and landslides.
This study deals with the case that was the field application of the microseismic monitoring tech... more This study deals with the case that was the field application of the microseismic monitoring techniques for the stability monitoring in a domestic mine. The usefulness and limitations of the microseismic techniques were examined through analyzing the microseismic monitored data. The target limestone mine adopted a hybrid room-and-pillar mining method to improve the extraction ratio. The accelerometers were installed in each vertical pillar within the test bed which has the horizontal cross-section 50 m × 50 m. The measured signals were divided into 4 types; blasting induced signal, drilling induced signal, damage induced signal, and electric noise. The stability analysis was performed based on the measured damage induced signals. After the blasting in the mining section close to the test bed, the damage of the pillar was increased and rockfall near the test bed could be estimated from monitored microseismic data. It was possible to assess the pillar stability from the changes of daily monitored data and the proposed safety criteria from the accumulated monitored data. However, there was a difficulty to determine the 3D microseismic source positions due to the 2D local sensor arrays. Also, it was needed to use real-time monitoring methods in domestic mines. By complementing the problems encountered in the mine application and comparing microseismic monitored data with mining operations, the microseismic monitoring technique can be used as a better safety method.
An experimental and numerical study was carried out to study solidliquid mixture upward hydraulic... more An experimental and numerical study was carried out to study solidliquid mixture upward hydraulic transport of solid particles in vertical and inclined annuli with rotating inner cylinder. Lift forces acting on a fluidized particle plays a central role in many importance applications, such as the removal of drill cuttings in horizontal drill holes, sand transport in fractured reservoirs, sediment transport and cleaning of particles from surfaces. Effect of annulus inclination and drill pipe rotation on the carrying capacity of drilling mud and pressure drop in a slim hole annulus have been measured for fully developed flows of water and of aqueous solutions of sodium carboxymethyl cellulose (CMC), respectively. For water and CMC solution the higher the concentration of the solid particles is, the larger the pressure gradients become.
It is difficult to solve problems regarding the adjustment on demand and supply of liquefied natu... more It is difficult to solve problems regarding the adjustment on demand and supply of liquefied natural gas (LNG) due to seasonal variations of domestic demand of LNG, discordance among import pattern, limits of storage facilities, and so on. Therefore, it is very important to secure large LNG storage facilities and to stabilize LNG supply management on a long term basis. A new concept of storing LNG in a lined rock cavern with containment system has been developed by Geostock, SKEC and SN Technigaz with the help of KIGAM. To demonstrate the feasibility of this concept and validate numerical modelling and calculations, a pilot plant was constructed at KIGAM in Daejeon Science Complex in 2003, which had been under operation for storing LN2 (Boiling Temperature:-196°C) since January 2004, and now been decommissioned. The objective of this study is to examine the realscale applicability of a lined underground rock storage system, which has been verified by a successful operation of the Daejeon LNG pilot plant. The new technology has many advantages of better economy, safety and environment protection, for above-ground and in-ground storage systems. The results of this study may promote the first ever real scale underground LNG storage system in a rock cavern.
Journal of the Korean Society of Mineral and Energy Resources Engineers, Apr 1, 2013
The physical properties and coagulation of suspended solids in a settling pond designed to contro... more The physical properties and coagulation of suspended solids in a settling pond designed to control flying rock dust during screening of limestone ores in O limestone mine were evaluated. The neutralization capacity of settled sludge was also studied. Turbidity at the inlet and outlet of the settling pond was measured as 2,264 and 1,228 NTU, respectively. The later was still considered to be a high level of turbidity just before recycling. The particle size (d(0.5)) of suspended solids in the settling pond ranged 5.1 to 10.1 μm. Jar tests showed improved coagulation of suspended solids at a pH 3 to 5 as concentration of coagulant, increased from 1 to 10 mg/L and as period of mixing increased. Neutralization evaluation results revealed that fine sludge <1 mm in size from the settling pond increased the pH of acid mine drainage to pH 6 and could remove dissolved Al and Fe within 10 minutes.
This paper reports the background information and the initial results obtained from the pilot und... more This paper reports the background information and the initial results obtained from the pilot underground LNG (liquefied natural gas) storage cavern in Korea, where all natural gas is stored in the condition of liquid phase. Many attempts have been made in the past to store LNG underground in unlined containment, though without success. A new concept for storing LNG in a lined rock cavern has been developed to provide a safe and cost-effective solution. It consists of protecting the host rock against the extremely low temperature and providing a liquid and gas tight liner. One of the most significant problems related to underground storage of cryogenic material is the need to prevent the leakage of liquid and gas from the containment system to the rock mass caused by tensile failures due to shrinkage of the rock mass around the caverns. In order to verify the technical feasibility of this storage concept, a pilot plant was constructed for storing Liquefied Nitrogen and has been in operation since January 2004, though has now been decommissioned. The overall monitored results from the pilot operations confirmed that the construction and operation of underground LNG storage in lined rock caverns is technically feasible for a rock engineering point of view. The results of this study may promote the first ever real scale underground LNG storage system in a rock cavern in the world.
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Papers by So-Keul Chung