• Explosives and Blasting
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• v.31 no.2
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• pp.6-13
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• 2013

Recently, complaints or environmental problems caused by the noise and dust generated from crusher of the mine and quarry are emerging. Therefore mining facilities such as crushers and mills have been installed in an underground. In order to facilitate crusher equipments in the underground, excavation of large space is required and then the stability of the large space underground structure is an important issue. In this study, the blast experiments, which use a block of the limestone, are performed. Based on the blast experiments, the numerical model was prepared and simulated using dynamic fracture process analysis code(DFPA) with considering the rising time of applied borehole pressure and microscopic tensile strength variation. Comparing the non-dimensional crack length and no-dimensional tensile strength obtained from blast experiments and numerical analyses, the input parameters of DFPA code for predicting a radial tensile crack in limestone blasting were determined.

• Explosives and Blasting
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• v.36 no.3
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• pp.29-38
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• 2018

With the recent industrial developments and economic development nationally, there has been a rapidly increasing demand for the use of underground space as locations for establishing social infrastructure and various convenience facilities. In this study, a mist-control system was developed to reduce the generation of dust in underground blasting. To enhance the dust-reduction effect, a guiding device was developed which is capable of adjusting the direction of the spray toward's the blasting face of mine or tunnel. A numerical analysis was performed by using the AUTODYN software, and results were compared with those published in basic experiments. To verify the mist-diffusion effect according to the position of explosives in a water bag, numerical analyses were conducted for the following cases: Explosives were set in the middle, and in the bottom of the water bag. The optimum condition was external detonation and center charge. The mist particle size from the result was suitable for the reduction of dust after blasting in underground mine and tunnel.

• The Journal of Engineering Geology
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• v.7 no.3
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• pp.229-245
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• 1997

There are Common aspects between the underground oil storage cavern and the radioactive waste disposal facility. Both facilities use appropriately the intrinsic natural berrier characteristics of the rock mass and additionally the engineered barrier system for the long term safety. The geological structures and their hydrogeological characteristics in a faactured rock mass act a major role in the safety and performance of the underground oil storage facility through the design, construction and the operation stages. Because the fracture system distributed in a fractured rock block is complicated owing to their own geometrical and hydrogeological attributes, the hydrogeological perforrmrnce of the facility would depend mainly upon the understandings of their characteristics. This study reviews the uncertainties and key issues which have to be considered to analyse the groundwater flow system in a fractured rock mass and proposes the techniques applicable to characterize the hydrogeological parameter.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.15 no.1
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• pp.21-28
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• 1997

Since beginning of subway construction in 1974, for supplying the demand for increasing urban traffic and solving the traffic jam due to expansion of society and elevation of an individual income, the $1^{st}\;and\;2^{nd}$ construction have been almost done and $3^{rd}$ has been driving forward. However, according to an increment of com-mon usage with the passage of time, structures are superannuated and the amount of improvement and repairs keeps on increasing continuous. And many problems are taking place at underground space because of new constructions for underground facilities such as urban gas, electric power, waterworks, and sewerage. In consequence. The consideration of a counterplan for safety is required deeply This study analyzed problems on maintenance of structure about $1^{st}$ class subway, and will present means that a manage civil structures scientifically and systematically by using GSIS concept that imported into several organizations for facility management recently as making digital graphic elements and historic data into a database rather than using an old method - documents and paper drawings.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1964-1969
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• 2010

Recently, as construction market scale is getting bigger and transportation industry is developing, the underground structure construction such as subway, tunnel (excavation box) or shield tunnel structure is becoming more diverse, and its demand is gradually increasing. However, for the concrete structures constructed underground, the water leakage is occurred due to the expansion joint and construction joint, or movement, uneven settlement, excessive load and vibration during application causing cracks. Many waterproofing method and materials are used in jobsites, but areas such as underground railroad and subway that has movement and vibration at all times, the ability of waterproofing layer is declined causing repetitive water leakage due to crack, erosion and separation, which is a vicious cycle. Therefore, this study evaluates the responsiveness to a movement for adhesive/flexible waterproofing material that can cope with the vibration and the movement of the structure. Also to recommend a waterproofing technology that can cope with structure movement through examples of actual jobsite applications such as subway and tunnel where there are constant movement and vibration.

• Tunnel and Underground Space
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• v.10 no.3
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• pp.418-429
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• 2000

Many Studies of tunnel and tunnelling safety have been developed continuously based on the increasing social interests in underground space since 1990's in Korea. Because the growth of population in metropolitan has been accelerated at a faster pace than the development of the cities, underground facilities have been created as a great extent in view of less land space available. In this study, a lot of types of tunnel failure were surveyed and the detail causes were studied after many cases of tunnel failure were collected. There were suggested brief countermeasure of tunnel failure through case study. An expert system was developed to predict the safety of tunnel and choose proper tunnel reinforcement system using fuzzy quantification theory and fuzzy inference rule based on tunnel information database. The comparison result between the predicted reinforcement system level and measured ones was very similar. In-situ data were obtained in three tunnel sites including subway tunnel under Han river. This system will be very helpful to make the most of in-situ data and suggest proper applicability of tunnel reinforcement system developing more resonable tunnel support method from dependance of some experienced experts for the absent of guide.

• Journal of the Korean Geotechnical Society
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• v.21 no.9
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• pp.35-44
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• 2005

Recently, underground cavities such as limestone cavity and abandoned mine give rise to a lot of damage in SOC facilities. But there are many difficult problems such as delay of the working terms and enormous economic losses in finding a new method and changing construction design. In this study, a new filling material for underground cavities was developed using the stone-dust classified as industry waste polluting environment. As a result of test, filling material properties was that a compressive strength was $34{\~}60\;kgf/cm^2$, a change ratio in length was $0.268{\~}0.776\%$ and water absorption was $34.3{\~}46.9\%$. Also as a result of suspended mass test and pH test, it was confirmed that the developed filling material has a characteristic of non-separating in water and it was an environmentally friendly material.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.6
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• pp.973-984
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• 2017

There is a growing need to apply TBM tunnelling method for the construction of underground facilities such as subways and utility tunnels in urban areas. Due to the variability and uncertainty of the ground, tunnelling in urban areas has various safety hazards which could cause damage to people and properties and it is very costly to recover from accidents. Therefore, it is very important to identify hazards from the planning and design phase and to establish risk mitigation measures. In this study, a total of 31 hazards affecting the stability of TBM tunnelling works in urban areas were listed from both the technical literature and correspondence with experts in tunnelling area. The importance and priorities of the hazards were analyzed by conducting Delphi technique, which is a decision-making method by consensus among experts. Finally, 12 hazards that satisfy the content validity criteria were settled and could be used as major control factors for accident prevention during TBM tunnelling works.

• Journal of the Korean Institute of Gas
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• v.19 no.4
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• pp.62-67
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• 2015

In this paper, the consequence analysis has been evaluated for the damage effects of the LPG storage tanks when they are installed on the ground or underground. They should be performed to identify measures to reduce risks for the LPG storage tanks which are more widely used. In order to conduct a damage effect evaluation of the LPG storage tanks installed underground, FDS was used to simulate the LPG storage tanks installed and housed within a facility. The maximum pressure of the storage facilities for the LPG storage tanks has been calculated from the FDS, and it's results are used as an input variable for Phast which is a commercial software for evaluating the damage effects. Getting results from the consequence analysis and computational simulations(diffusion range of LFL and UFL, jet fire or explosions) were quantitatively presented for the damage effects.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.83-89
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• 2009

The environment of electrical power industry is now faced on problems such as electric rates, an increasing sensitivity in society with environmental issues and energy factors. Up to now, reliability is greatly influenced by maintenance and environmental factors that are unique to the electric utilities. The reliability is a characteristic assigned to the electric power systems's function which is related to the concept of installment of equipment. Therefore this reports's key finding is that it is important that the utilities track their individual components' value over investment expense of their installed components. This can be accomplished to consider the cases of foreign electric power companies and take into account the various possible installment ways of equipment in Korea. These results are expected to be used as a reference material for design underground distribution facilities and future applications.