• The Journal of Engineering Geology
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• v.33 no.4
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• pp.519-530
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• 2023

Moye's analytical solution was examined as a method for constant-head tests under steady-state conditions, and results were compared with transient-state analyses in in situ hydraulic tests. The sensitivity of hydraulic conductivities calculated using Moye's method increased with the length of the test section, which should be as large as possible under test conditions. Particularly in low-permeability media with less than 10^-8 m/sec of hydraulic conductivity, hydraulic conductivity is lower than that under transient-state conditions and can be recalculated by adjusting the boundary between radial and spherical flow assumed in Moye's equation. Constant-head tests performed in the research borehole at the KAERI Underground Research Tunnel (KURT) indicated that transmissivities derived from the constant-head withdrawal test under transient-state conditions in low-permeability media were higher than those derived from steady-state tests, likely because the groundwater flow boundary was smaller than the "half of the test-section length"assumed by Moye's equation. When interpreting constant-head test results for crystalline rock, the hydrogeological properties of the medium may be better understood by considering assumed conditions accompanying analysis of the steady-state condition and comparing them with results for the transient-state analysis, rather than simply assuming properties based on steady-state analyses.

• The Journal of Engineering Geology
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• v.34 no.1
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• pp.39-49
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• 2024

The construction of underground infrastructure is garnering growing increasing research attention owing to population concentration and infrastructure overcrowding in urban areas. An important associated task is establishing a monitoring system to evaluate stability during infrastructure construction and operation, which relies on developing techniques for ground investigation that can evaluate ground stability, verify design validity, predict risk, facilitate safe operation management, and reduce construction costs. The method proposed here uses satellite imaging in a cost-effective and accurate ground investigation technique that can be applied over a wide area during the construction and operation of infrastructure. In this study, analysis was performed using Synthetic Aperture Radar (SAR) data with the time-series radar interferometric technique to observe surface displacement during the construction of urban underground roads. As a result, it was confirmed that continuous surface displacement was occurring at some locations. In the future, comparing and analyzing on-site measurement data with the points of interest would aid in confirming whether displacement occurs due to tunnel excavation and assist in estimating the extent of excavation impact zones.

• Tunnel and Underground Space
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• v.34 no.5
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• pp.477-502
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• 2024

To effectively dispose of high-level radioactive waste, it is crucial to understand the geological characteristics of the deep rock at the disposal site where the disposal facility will be located. Deep drilling is essential in this process and can obtain multidisciplinary deep rock characteristics by conducting tests using recovered cores and various tests using boreholes. However, in Korea, there are currently no established guidelines or procedures for deep drilling aimed at sit investigation and characterization for high-level radioactive waste disposal. This report proposes a deep drilling procedure based on five years from 2020 of multipurpose deep drilling experience conducted for various rock types by the Korea Institute of Geoscience and Mineral Resources. The proposed procedure includes various processes such as health, safety, and environments, pre-drilling work, drilling work, circulating drilling water management, site characterization evaluation parameter acquisition tests and measurements, and sampling. These procedures will need to be continuously revised and amended in the future to meet the needs of drilling and HLW disposal industries and related fields, as well as to strengthen quality assurance under the Nuclear Safety Act.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.4
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• pp.589-609
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• 2017

This study carried out the density and energy dispersive X-ray spectroscopy and particle size analysis which are the physical characteristics of coal dust by collecting samples of coal dust in the five domestic mines to control the coal dust through ventilation in the workplace for coal mining in the country. This will contribute to a more comfortable working environment by understanding the physical characteristics of the coal dust which is derived from any hard coal produced domestically. In particular, the result of PSA analysis showed that the size of coal dust sample for this study ranged from $0.007{\sim}88.614{\mu}m$ were the particles less than $3.5{\mu}m$, the size range responsible for pneumoconiosis. To observe the flow of coal dust collected on the wind speed, the fallout of coal dust produced by the wind tunnel for the wind was measured and the particle size analysis of coal dust fallout was carried out. In addition, airborne dust is measured according to the mine velocity by using a multi-stage Anderson sampler in the mine where fine dust is generated in a large amount and the wind speed is found out to control the coal dust below $3.5{\mu}m$. In addition, natural ventilation pressure of A mine was calculated to prevent over design of the main fan.

• Tunnel and Underground Space
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• v.2 no.1
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• pp.95-101
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• 1992

Norwegian technology related to preinvestigations, planning, design and construction of large underground caverns is wellknown worldwide. However, so far this technology is only slightly verified through scientiffic reports and documentation. The "Rock cavern stadium" research program is an interdisciplinary program related to the ongoing building and future use of Gjovik Olympic Subsite which is the largest cavern in the world for public purposes with a span of 61 meters and a height of 25 meters. The estimated budget for this program is about USD 4 million which is made possible through grants from The Royal Norwegian Council for Scientific and Industrial Research as well as through contributions from Norwegian and Swedish companies that are participating. The program is carried out in collaboration with The Foundation for Scientific and Industrial Research at the Norwegian Institute of Technology. The Norwegian Geotechnical Institute and The Eastern Norway Research Center. The research program will continue until the end of 1994 to ensure that input comes from a full period of use in this stadium with different activities like exhibitions, conferences, concerts etc being included as verification through full-scale measurements and observations. The research program has five subtasks. Three of these are related to subjects like Energy consumption. HVAC installations. Fire safety design, Engineering geology and Rock mechanics, Environmental aspects. The fourth subtask is concerned with the collection of basic data, results and experience from these three subtasks to provide a basis for national Norwegian guidelines related to this interdisciplinary subject area. The guidelines will first be presented as a manual for planning and engineering purposes. The realization of this research program is a unique opportunity to enhance the expertise that has been acquired from this cavern stadium. By involving research in this extraordinary project from the excavation and building phase to its subsequent use. this will give the participants know-how and expertise which is very much in demand internationally. The coordination of the international activities between the participants as well as preparation of participations and presentations in international conferences and symposium are included in the fifth task of this national research program.

• Tunnel and Underground Space
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• v.13 no.4
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• pp.304-315
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• 2003

In this paper, the DDA method with a new hydro-mechanical algorithm is used to study the effect of rock discontinuities on uplift and seepage in concrete gravity dam foundations. This paper presents an alternative method of predicting uplift and seepage at the base of concrete gravity dams. A sensitivity analysis was carried out to study the importance of several parameters on dam stability such as the orientation, spacing, and location of discontinuities. The study shows that joint water flow and adverse geological conditions could result in unusual uplift at the base of concrete gravity dams, well in excess of what is predicted with the classical linear or hi-linear pressure assumption. It is shown that, in general, the DDA program with the hydro-mechanical algorithm can be used as a practical tool in the design of gravity dams built on fractured rock masses.

• Tunnel and Underground Space
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• v.18 no.1
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• pp.69-79
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• 2008

Dokdo is a volcano edifice originating from an oceanic island that was formed around 3 million to 2.2 million years ago, and it consists of Dongdo(eastern island) and Seodo(western island). Even though Dokdo is a small volcanic island, Dokdo has infinite potential value and significant economic, social, scientific, and technical aspects due to its resources, ecological and territorial value. In addition, it is of national interest with regards to the dispute with Japan over the dominium of Dokdo. A need to evaluate the ground stability of Dokdo, especially in Dongdo, has been seriously raised recently due to the various cracks caused by the progressive weathering and corrosion. This study dealt with the geology and geological layers of Dokdo and identified the status of ground cracks as the previous research to evaluate the ground stability of zones of concern in Dongdo. Also, this study analyzed the relationships between physical and mechanical properties with rock types. The results showed that the values of rock properties in Dokdo are lower contrary to the general rocks in Korea, and tuff was especially affected by the weathering and corrosion.

• Tunnel and Underground Space
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• v.14 no.4
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• pp.295-303
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• 2004

For the deep underground excavation site with the geological complexity of soft seam and hard rock, the numerical analysis and in-situ measurement on the behaviors of roadway and surrounding rock according to stepwise excavation of the steep soft seam are carried out. The strata behavior is modeled using elasto-plastic FEM considering the empirical failure criteria of Hoek ＆ Brown and the strain-softening model. Hydraulic pressure capsule, MPBX and tape extensometer are installed around the roadway for the in-situ measurement of rock stress and deformation. Despite the complexity of geology and excavation procedure, the elasto-plastic analysis considering the empirical failure criteria of Hoek ＆ Brown and the strain-softening model shows good agreement with the in-situ measurement. Comparison of numerical modeling with in-situ measurement enables to predict the behaviors of the roadway and to obtain design parameters for the excavation and support at depth.

• Tunnel and Underground Space
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• v.17 no.6
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• pp.493-502
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• 2007

Measurements of hydraulic conductivity are point or interval values, and are highly limited in their number. Meanwhile, results of geophysical prospecting can provide the information of spatial variation of geology, and abundant in number. In this study, it was aimed to develop a data integration tool for constructing a hydraulic conductivity map by integrating geophysical data and hydraulic conductivity measurements. The developed code employed a geostatistical optimization method, simulated annealing (SA), and consists of 4 distinct computation modules by which from exploratory data analysis to postprocessing of the simulation were processed. All these modules are equipped with Graphical User Interface (GUI). Validation of the developed code was evaluated in-situ in characterizing hydraulic characteristics of highly permeable fractured zone.

• Tunnel and Underground Space
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• v.28 no.4
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• pp.304-324
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• 2018

Singapore government is strongly promoting the development and utilization of underground space in national level due to the nature of the city state which lacks the land. As well as conventional underground utilization in shallow depth such as metro and underground roads, large rock cavern utilization has been started after the successful completion of the underground ammunition depot in the rock, and Jurong Rock Cavern, the second large underground cavern project has just been completed. In this paper, after evaluating the conditions of the underground development in rock mass through the analysis of the geology of Singapore, the history and current status of underground development are examined. Several creative development plans from Singapore government such as underground reservoirs, underground automation logistics systems and underground warehouses storage etc. are introduced with technical issues. This paper also discusses the problems and issues related to the development of large underground space in rock mass in Singapore. It is expected that such active development of underground space in Singapore can give many opportunities and also challenges for rock engineering and industry in the future.