• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.285-285
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• 2020

본 연구에서는 국내 시설농업단지의 수리지질 특성을 고려한 개념 모델을 설정하여 수리전도도와 이격거리(주입정과 양수정 사이의 거리)에 대한 민감도 분석을 수행하였다. 개념 모델에는 자연적 특성(지형과 지질, 강수량, 수리전도도 등)과 인공적 특성(주입정과 양수정의 이격거리, 주입량과 양수량 등)이 입력되었으며, 민감도 분석은 수리전도도(10^-1 cm/sec, 10^-2 cm/sec, 10^-3 cm/sec, 10^-4 cm/sec)와 이격거리(10 m, 50 m, 100 m)를 조합한 12개의 시나리오로 수행하였다. 양수정의 하류부에 설정된 관측정의 지하수위 강하량은 수리전도도가 감소하고 이격거리가 멀어질수록 증가하였다. 동일한 이격거리에서 수리전도도에 의한 지하수위 강하량의 회귀분석을 통해 인공함양 대수층의 지하수위 변동은 수리전도도에 의해 지배적인 영향을 받음을 알 수 있었다. 인공함양 대수층의 수리전도도가 10^-2 cm/sec 이상인 조건에서는 주입정과 양수정의 이격거리에 따른 지하수위의 영향반경은 20 m 이내이었지만, 수리전도도가 10^-3 cm/sec 이하인 조건에서는 이격거리가 멀어질수록 지하수위의 영향반경이 급격하게 증가함을 확인하였다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.412-414
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• 2005

세계 각국은 지속가능한 지하수자원의 사용을 위해 지하수의 부존, 유동 및 수질특성을 파악하는 지하수조사를 수행하고 이를 기초로 수문지질도를 작성하고 있다. 이에 인터넷 검색을 통해 세계 192개국의 수문지질도의 작성현황에 대한 자료를 수집하였다. 국가규모의 수문지질도는 91개국, 지역규모 정밀수문지질도는 57개국의 제작하고 있는 것으로 파악되었다(검색을 통해 확인되지 않은 국가라고 하여도 제작을 하지 않는다는 의미는 아님). 또한 제작 시기별로는 러시아가 1930년에 가장 일찍 수문지질도를 작성하였으며 우리나라는 1990년 전북고창을 시작으로 2011년 100개시군구의 정밀수문도 작성이 계획되어 있다. 세계의 주요한 대부분의 나라는 시기에 차이는 있지만 수리지질(지하수)조사를 실시하여 수문지질도를 작성하고 있으며 최근에는 대부분 지질조사소(Geological Survey)가 조사 및 제작을 담당하고 있다. 지하수 조사내용과 수문지질도 작성 scale은 각국의 수리지질학적 조건에 따라 다르며 그에 따른 주제도 내용도 조금씩 다르다. 또한 지하수 이용 여건 및 수리지질학적 환경변화에 따라 일정주기로 반복 조사하고 있는 것으로 파악되었다.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.3
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• pp.253-257
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• 2013

Geology, hydrogeology, and geochemistry are the main technical siting factors of a geological repository for spent nuclear fuels. This paper evaluated the siting criteria of overseas geological repository with related to hydrogeologic properties, such as hydraulic conductivity, partitioning coefficient, dispersion coefficient, boundary condition, and water age. Each country establishes the siting criteria based on its important geological backgrounds and information, and social environment. For example, Sweden and Finland that have decided a crystalline rock as a host rock of a geological repository show different siting criteria for hydraulic conductivity. In Sweden, it is preferable to avoid area where the hydraulic conductivity on a deposition hole scale (~30m) exceeds $10^{-8}m/s$, whereas Finland does not decide any criterion for the hydraulic conductivity because of limited data for it. In addition, partitioning coefficients should be less than 10-1 of average value in Swedish crystalline bedrock. However, the area where shows 100 times less than average partitioning coefficients of radionuclides in crystalline rock should be avoided in Sweden. In German, the partitioning coefficients for the majority of the long-term-relevant radionuclides should be greater than or equal to $0.001m^3/kg$. Therefore, it is strongly required to collect much and exact information for the hydrogeologic properties in order to set up the siting criteria.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.312-315
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• 2006

배수공법으로 터널을 설계할 때 다양한 지질조건에 따라 터널내로 유입되는 지하수 용수량과 배수관의 배수능력을 비교 검토하였다. 기존 설계 기준에 의한 터널 배수관은 다양한 지질조건을 가지는 대수층의 수리전도도에 따라 안정성 여부가 달라지는 것을 알 수 있었다. 기존 배수관 (${\Phi}300m/m$)으로 터널을 설계할 경우 투수성이 좋은 석회암 구간 및 파쇄대 구간에서는 문제가 생길 가능성이 높고, 풍화 받지 않은 암반층의 경우에는 터널길이 20km까지 지하수 용수량을 수용 가능한 것으로 판단된다.

• 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.

• Tunnel and Underground Space
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• v.29 no.3
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• pp.197-213
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• 2019

We simulated the fault reactivation experiment conducted at 'Main Fault' intersecting the low permeability clay formations of Mont Terri Underground Research Laboratory in Switzerland using TOUGH-FLAC simulator. The fluid flow along a fault was modelled with solid elements and governed by Darcy's law with the cubic law in TOUGH2, whereas the mechanical behavior of a single fault was represented by creating interface elements between two separating rock blocks in FLAC3D. We formulate the hydro-mechanical coupling relation of hydraulic aperture to consider the elastic fracture opening and failure-induced dilation for reproducing the abrupt changes in injection flow rate and monitoring pressure at fracture opening pressure. A parametric study was conducted to examine the effects of in-situ stress condition and fault deformation and strength parameters and to find the optimal parameter set to reproduce the field observations. In the best matching simulation, the fracture opening pressure and variations of injection flow rate and monitoring pressure showed good agreement with field experiment results, which suggests the capability of the numerical model to reasonably capture the fracture opening and propagation process. The model overestimated the fault displacement in shear direction and the range of reactivated zone, which was attributed to the progressive shear failures along the fault at high injection pressure. In the field experiment results, however, fracture tensile opening seems the dominant mechanism affecting the hydraulic aperture increase.

• The Journal of Engineering Geology
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• v.31 no.4
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• pp.589-601
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• 2021

Artificial recharge technology is a method for solving problems such as groundwater level drop and ground subsidence caused by groundwater withdrawal. This study investigated the applicability of using the hydraulic conductivity of an aquifer to predict injection test results for aquifer restoration. Pumping and injection tests were performed under the same conditions as those for the artificial injection facility located in Icheon, Gyeonggi-do. The hydraulic conductivity of the aquifer, which plays a decisive role in restoring the groundwater level, was derived from the pumping test. A numerical model of a simplified on-site aquifer was constructed, and a transient analysis was applied with the same conditions as the pumping test. The correlation between the measured and the resulting model values is strong (R² = 0.78). The injection test was performed in a sedimentary layer composed of silt sand and clay sand. From the results of the injection test, an empirical formula was derived using Theim's formula, which is a common well analysis solution to determine the parameters of the aquifer from time-level data. The model values from the empirical formula have a high degree of correlation (R² = 0.99) with measured values. Under specific conditions, for areas where it is difficult to conduct an injection test, the formula from this study, which relies on the hydraulic conductivity of the aquifer determined through the pumping test, may be used to predict reliable injection rates for groundwater restoration.

• The Journal of Engineering Geology
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• v.20 no.2
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• pp.169-181
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• 2010

This study aimed at simulating several responses to stresses caused by the ground water level variations around the K-1 oil stockpile. For this simulation, we considered the characteristic hydrogeological condition including the special occurrence of long and thick acidic dyke, which is regarded as the main geological structure dominating the ground water flow system at this study area. We activated twenty-four imaginary wells which are located in northern and southern area around central K-1 site. Each neighboring distance is altogether 300 m and whole distance between K-1 site and remote wells is 1,200 m. Through the modeling, we operated the long-term and continuous pumping tests and finally categorized five zones based on maximum pumping rates for the imaginary wells; zone I within 300 meter distance from K-1 site with a pumping rate of 50 $m^3/day$; zone II between 300 to 600 meter distance from K-1 site with a pumping rate of 75 $m^3/day$; zone III between 600 to 900 meter distance from K-1 site with 150 $m^3/day$; zone IV between 900 to 1,200 meter distance from K-1 site with 300 $m^3/day$; and zone V of acidic dyke area. At zone V, especially because of their possibility of high transmissivity for groundwater flow, it is necessary to control and restrict groundwater discharge.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.387-387
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• 2017

인공함양 시설을 설계 및 운영하는 단계에서 설치 예정부지의 자연적 특성(지형, 지질, 기후 등)과 인공적 특성(주입정과 양수정의 거리, 주입량, 양수량 등)은 중요한 인자라고 볼 수 있다. 인공함양 예정 부지의 개념모델을 설정하고 수리전도도와 이격거리(주입정과 양수정의 직선거리)에 대한 민감도 분석을 수행하였다. 인공함양 예정 부지는 충적대수층이며, 인공함양 주입량과 양수량은 $150m^3/day$로 동일하게 설정하였다. HydroGeoSphere 모델링을 통한 민감도 분석은 수리전도도($10^{-1}cm/sec$, $10^{-2}cm/sec$, $10^{-3}cm/sec$, $10^{-4}cm/sec$)와 이격거리(10 m, 50 m, 100 m) 조건에 대해 총 12회 수행하였다. 수리전도도가 $10^{-1}cm/sec$ 및 $10^{-2}cm/sec$인 경우의 모델링 결과, 이격거리가 100 m 범위 이내에서는 지하수위 변동이 발생하지 않았다. 수리전도도가 $10^{-3}cm/sec$인 경우의 모델링 결과, 이격거리가 10 m일 때 5 m 이내의 수위하강이 발생하고 영향반경은 약 14 m 정도로 나타났고, 이격거리가 50 m일 때 5 m 이내의 수위하강이 발생하고 영향반경은 약 31 m 정도로 나타났고, 이격거리가 100 m일 때 5 m 이내의 수위하강이 발생하고 영향반경은 약 34 m 정도로 나타났다. 수리전도도가 $10^{-4}cm/sec$인 경우의 모델링 결과, 이격거리가 증가할수록 양수에 의한 수위하강과 영향반경이 증가하였으며, 낮은 수리전도도로 인해 양수로 인한 수두손실을 회복할 수 없었기에 양수정 주변에서 반경 수십 m 이상의 수두하강 영역을 형성하고 주입정 근처에서는 주입속도가 대수층의 투수능력에 비해 상당히 높기 때문에 5 m 정도의 수위상승이 나타났다. 모델링 결과를 분석하여, 수리전도도가 $10^{-3}cm/sec$ 이하이고 이격거리가 10 m 범위 이상인 충적대수층에 $150m^3/day$를 주입하면서 동시에 $150m^3/day$를 양수하는 시스템에서는 지하수위변동이 발생하므로 주입량과 양수량의 조절이 필요하다는 것을 확인하였다.

• Journal of the Korean Geotechnical Society
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• v.18 no.6
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• pp.5-16
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• 2002

A hydrogeomechanical numerical model is presented to evaluate rainfall impacts on groundwater flow in slopes and slope stability. This numerical model is developed based on the fully coupled poroelastic governing equations for groundwater flow in deforming variably saturated geologic media and the Galerkin finite element method. A series of numerical experiments using the model developed are then applied to an unsaturated slope under various rainfall rates. The numerical simulation results show that the overall hydromechanical slope stability deteriorates, and the potential failure nay initiate from the slope toe and propagate toward the slope crest as the rainfall rate increases. From the viewpoint of hydrogeology, the pressure head and hence the total hydraulic head increase as the rainfall rate increases. As a result, the groundwater table rises, the unsaturated zone reduces, the seepage face expands from the slope toe toward the slope crest, and the groundwater flow velocity increases along the seepage face. From the viewpoint of geomechanics, the horizontal displacement increases, and the vertical displacement decreases toward the slope toe as the rainfall rate increases. This may result from the buoyancy effect associated with the groundwater table rise as the rainfall rate increases. As a result, the overall deformation intensifies toward the slope toe, and the unstable zone, in which the factor of safety against shear failure is less than 1, becomes thicker near the slope toe and propagates from the slope toe toward the slope crest. The numerical simulation results also suggest that the potential tension failure is likely to occur within the slope between the potential shear failure surface and the ground surface.