• Tunnel and Underground Space
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• v.22 no.1
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• pp.1-11
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• 2012

Thermal energy storage is defined as the temporary storage of thermal energy at high or low temperatures for later use in need. The energy storage can reduce the time or rate mismatch between energy supply and demand, and thus it plays an important role in conserving energy and improving the efficiency of energy utilization, especially for renewable energy sources which provide energy intermittently. Underground thermal energy storage (UTES) can have additional advantages in energy efficiency thanks to low thermal conductivity and high heat capacity of surrounding rock mass. In this paper, we introduced the technologies of underground thermal energy storage and rock caverns for hot water storage in Sweden.

• Tunnel and Underground Space
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• v.23 no.5
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• pp.327-336
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• 2013

Approximately 70% of the Korean peninsula is composed of mountains, around 99,274 $km^2$. Even worse, population rate of Korea is the No.3 in the world now. Accordingly, it is necessary to develop the potential underground space actively with the concept of another territory to be utilized. The development of underground space should be considered not a choice but an indispensable issue. Since 1970s, many large-scale underground structures have been constructed like as crude-oil storage bins, liquefied petroleum gas storage caverns, and underground pumped storage powerplants. Also, In urban area, the underground facilities such as subway networks, underground shopping mall, underground pedestrian network, electric power tunnels, and car parking lots have been used extensively. The scale of Yeosu oil and gas underground storage facility and Seoul subway systems are one of the massive scale in the world. Recently, the trend of the development of underground space becomes more diverse and larger scale. The current status of Korean underground space developments and strategy are described in this paper.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.381-391
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• 2008

The eigenvalue technique is introduced to overcome the problem of truncation errors caused by temporal discretization of numerical analysis. The eigenvalue technique is different from simulation in that only the space is discretized. The spatially discretized equation is diagonized and the linear dynamic system is then decoupled. The time integration can be done independently and continuously for any nodal point at any time. The results of eigenvalue technique are compared with the exact solution and FEM numerical solution. The eigenvalue technique is more efficient than the FEM to the computation time and the computer storage in the same conditions. This technique is applied to the solute transport analysis in nonuniform flow fields around underground storage caverns. This method can be very useful for time consuming simulations. So, a sensitivity analysis is carried out by using this method to analyze the safety of caverns from nearly located contaminant sources. According to the simulations, the reaching time from source to the nearest cavern may takes 50 years with longitudinal dispersivity of 50 m and transversal dispersivity of 5 m, respectively.

• 한국지구물리탐사학회:학술대회논문집
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• 1999.08a
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• pp.117-136
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• 1999

The geophysical survey at pre-investigation stage can hardly provide the detailed information on geological structure of site which has difficulty in access and thick overburden. The TSP (VSP applied in tunnel) survey at post-investigation stage can show the detailed geology ahead of tunnel and around cavern. The TSP survey was carried out at the Pyongtaek LPG storage cavern site during the cavern excavation and provided the location and orientation of the fault inferred below Namyangho. In order to confirm the result of TSP survey four boreholes were drilled in access tunnel. The fault was also detected by borehole survey and the location was coincided with the result of TSP survey. Depend on the result of TSP survey and core logging, the design such as cavern layout and length could have been changed. As another case history the TSP survey was performed at the Mumeuje road tunnel which has poor geological information due to thick overburden. The support design was also changed on the base of TSP survey.

• Tunnel and Underground Space
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• v.12 no.1
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• pp.43-51
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• 2002

한국원자력연구소에서는 80년대 말부터 1996년까지 저준위 방사성 영구처분 연구사업을 수행한 바 있으며 2000년부터는 국가원자력중장기연구개발사업의 일환으로 한국원자력연구소와 한국수력원자력주식회사가 동굴 처분 관련 안전성 평가 연구를 공동 수행하고 있다. 본 기술 보고에서는 그 동안 개발된 연구 개발 성과들을 중심으로 중저준위 방사성폐기물 처분장 장기 안전성 평가에서 고려되어야 할 요소들과 현재까지 정립된 안전성 평가 방안들에 관하여 정리하였다.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 1999.03a
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• pp.59-64
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• 1999

지하암반은 계절적 대기온도 변화의 영향을 거의 받지 않는 온도조건 및 뛰어난 단열성으로 인해 물류의 저온냉동저장이나 액화연료의 저장 등을 위한 좋은 대상으로 인식되고 있다. 이러한 분야에 있어서 암반의 열물성 및 열유동 특성은 매우 중요한 요소로서, 이는 장기적인 에너지절약 및 지하구조물의 열역학적 안정성의 정확한 평가와 직접적 연관이 된다. (중략)

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.97-99
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• 2006

Occurrence of Hwangji pond in Taebaek karst area was investigated in various hydrogeochemical ways and it is found out that there are underground cavern network and sinkholes under the pavement of Taebaek city. It is partially proved by dye tracing method.

• Tunnel and Underground Space
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• v.6 no.1
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• pp.19-29
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• 1996

Back analysis model, capable of calculating the mechanical properties and the in-situ stresses of jointed rock mass, was developed based on the inverse method using a continuum theory. Constitutive equation for the behavior of jointed rock contains two unknown parameters, elastic modulus of intact rock and stiffness of joint, hence algorithm which determines both parameters simultaneously cannot be established. To avoid algebraic difficulties elastic modulus of intact rock was assumed to be known, since the representative value of which would be quite easily determined. Then, the ratio ($\beta$) of joint stiffness to elastic modulus of intact rock was assigned and back analysis for the behavior of jointed rock was carried-out. The value $\beta$ was repeatedly modified until the elastic modulus from back analysis became very comparable to the predetermined value. The joint stiffness could be calculated by multipling the ratio $\beta$ to the final result of elastic modulus. Accuracy and reliability of back analysis procedure was successfully testified using a sample model simulating the underground opening in the jointed rock mass. Applicability of back analysis model for the underground excavation in practice was also verified by analyzing the mechanical properties of jointed rock in which underground oil storage cavern were under construction.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1994.10a
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• pp.201-208
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• 1994

To secure long-term structural safety of underground openings for radioactive waste disposal, the proper structural safety analyses are required. Especially, the structural analysis for underground openings should consider the effects of groundwater pressure. The objective of this study is to develop the structural analysis method for saturated rock masses. In this study, the interaction between groundwater distribution and structural behavior of rock masses are carried out to develop the structural analysis method of saturated rock masses. Then, a 3-Dimensional Multi-Phase Dynamic Analysis Program (MPDAP-3D) has been developed by modifying the existing MPDAP which is based on the concept of 2-dimensional two-phase media.

• Tunnel and Underground Space
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• v.8 no.1
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• pp.67-73
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• 1998

This paper presents the results of deformation measurement and numerical analysis carried out to study the behaviour of the rock mass around large underground oil storage caverns. Displacements during excavation have been monitored using borehole extensometers which had been installed before the excavation of caverns proceeded. Numerical analysis has been carried out to examine the three-dimensional behaviour of rock and the face advance effect. The input parameters for this analysis were determined from the results of laboratory and field tests. The deformation modulus of the rock mass was determined from plate loading test at the site and in-situ stresses were measured from the overcoring method with USBM deformation gauge. The results from this study gave a clear picture for three-dimensional behaviour of the rock mass, hence would be used for the optimum design.