• 지질공학
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• 제18권1호
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• pp.69-81
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• 2008

산사태연구는 산사태를 발생시키는 여러 인자들의 상호관계를 규명하는 방법, 확률론적으로 산사태 발생가능성을 예측하는 방법 사태물질의 이동경로와 확산범위를 산정함으로써 산사태 위험성을 평가하는 방법 등으로 구분할 수 있다. 우리나라에서 발생된 대부분의 산사태는 여름철의 집중호우에 기인되는 것으로 기반암 상부의 토층에서 발생되며, 강우조건, 지형조건과 지질 및 토질특성 등에 영향을 받는 것으로 알려져 있다. 산사태 조사부터 위험성평가에 이르기까지의 산사태연구는 다양한 산사태를 체계적으로 조사하고 해석함으로써 공학적 관점에서 여러 특징들을 관찰하고 그 특성들을 총괄적으로 해석하여야만 한다. 이 연구에서는 경상남도 마천지역을 대상으로 산사태 현장조사를 수행하였다. 조사결과를 토대로 자연사면 산사태에 대한 최적의 표준모델로 활용할 수 있는 산사태 조사 및 해석 기법을 제안하고자 한다.

• 방사성폐기물학회지
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• 제20권4호
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• pp.429-453
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• 2022

Numerical modeling and scenario composition are needed to characterize the geological environment of the disposal site and analyze the long-term evolution of natural barriers. In this study, processes and features of the hydro-mechanical behavior of natural barriers were categorized and represented using the interrelation matrix proposed by SKB and Posiva. A hydro-mechanical coupled model was evaluated for analyzing stress field changes and fracture zone re-activation. The processes corresponding to long-term evolution and the hydro-mechanical mechanisms that may accompany critical processes were identified. Consequently, practical numerical methods could be considered for these geological engineering issues. A case study using a numerical method for the stability analysis of an underground disposal system was performed. Critical stress distribution regime problems were analyzed numerically by considering the strata's movement. Another case focused on the equivalent continuum domain composition under the upscaling process in fractured rocks. Numerical methods and case studies were reviewed, confirming that an appropriate and optimized modeling technique is essential for studying the stress state and geological history of the Korean Peninsula. Considering the environments of potential disposal sites in Korea, selecting the optimal application method that effectively simulates fractured rocks should be prioritized.

• Steel and Composite Structures
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• 제47권4호
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• pp.451-454
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• 2023

Landslides are one of the natural disasters that cause a lot of financial and human losses every year It will be all over the world. China, especially. The Mainland China can be divided into 12 zones, including 4 high susceptibility zones, 7 medium susceptibility zones and 1 low susceptibility zone, according to landslide proneness. Climate and physiography are always at risk of landslides. The purpose of this research is to prepare a landslide hazard map using the Hierarchical Analysis Process method. In the GIS environment, it is in a part of China watershed. In order to prepare a landslide hazard map, first with Field studies, a distribution map of landslides in the area and then a map of factors affecting landslides were prepared. In the next stage, the factors are prioritized using expert opinion and hierarchical analysis process and nine factors including height, slope, slope direction, geological units, land use, distance from Waterway, distance from the road, distance from the fault and rainfall map were selected as effective factors. Then Landslide risk zoning in the region was done using the hierarchical analysis process model. The results showed that the three factors of geological units, distance from the road and slope are the most important have had an effect on the occurrence of landslides in the region, while the two factors of fault and rainfall have the least effect The landslide occurred in the region.

• 터널과지하공간
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• 제29권5호
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• pp.356-366
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• 2019

다양한 TBM 성능 예측 모델이 개발되었기만 대부분 관입율 예측에 한정되어 있다. 일부 모델들이 수식과 그래프를 이용하여 TBM 가동율을 추정하는 방법을 제시하기도 하지만, TBM 가동율에 대한 연구는 매우 드문 편이다. TBM 가동율은 TBM 장비의 종류, 운영, 유지보수, 지질 조건, 시공자의 경험 등에 영향을 받는다. 본 연구에서는 100여개 이상의 사례 분석을 통해서 TBM 가동율과 RMR, 암종 등의 지반 조건, TBM의 종류, 터널의 연장 및 직경 등과의 관계를 조사하였다. 단순 및 다중 회귀분석을 수행하여 TBM 가동율 예측모델을 개발하였다. 암종 등의 지반조건, TBM의 종류, 터널의 연장 및 직경 등을 설명 변수로 갖는 회귀모델은 낮은 상관계수를 나타내었다. RMR을 설명변수로 갖는 회귀모델이 더 높은 상관계수를 나타내었다.

• Geomechanics and Engineering
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• 제30권2호
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• pp.187-199
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• 2022

Kriging metamodel, as a flexible machine learning method for approximating deterministic analysis models of an engineering system, has been widely used for efficiently estimating slope reliability in recent years. However, the autocorrelation function (ACF), a key input to Kriging that affects the accuracy of reliability estimation, is usually selected based on empiricism. This paper proposes an adaption of the Kriging method, named as Genetic Algorithm optimized Whittle-Matérn Kriging (GAWMK), for addressing this issue. The non-classical two-parameter Whittle-Matérn (WM) function, which can represent different ACFs in the Matérn family by controlling a smoothness parameter, is adopted in GAWMK to avoid subjectively selecting ACFs. The genetic algorithm is used to optimize the WM model to adaptively select the optimal autocorrelation structure of the GAWMK model. Monte Carlo simulation is then performed based on GAWMK for a subsequent slope reliability analysis. Applications to one explicit analytical example and two slope examples are presented to illustrate and validate the proposed method. It is found that reliability results estimated by the Kriging models using randomly chosen ACFs might be biased. The proposed method performs reasonably well in slope reliability estimation.

• Nuclear Engineering and Technology
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• 제56권9호
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• pp.3950-3960
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• 2024

As a solution to the problem of spent nuclear fuels (SNFs), the disposal of SNF has gained attention from nations using nuclear energy because of hazards posed to the ecosystem. Among many proposed solutions, the most promising method is to dispose of SNF in a deep geological repository (DGR) which utilizes the multi-barrier concept developed by Finland and Sweden. Here, a new fully-coupled Thermal-Hydraulic (TH) code HADES (High-level rAdionuclide Disposal Evaluation Simulator) is developed using the MOOSE framework. This new code suggests basic numerical tools, such as a non-linear solver and finite element discretization, to assess the safety performance of disposal systems. The new TH code considered various TH behavior using Richards' flow approach, assuming gas pressure is constant. The HADES showed promising results when it was compared to various TH codes validated from DECOVAELX-THMC projects. When the single-canister model was utilized to estimate the TH behavior of the Korean Reference disposal System, although it showed significant saturation reduction due to the evaporation of water, the temperature was maintained under the thermal criteria limit, which is 100 ℃. In addition, the new code estimated temperature and degree of saturation of the multi-canisters model, considering two or three canisters, it showed a slightly lower temperature, 5 ℃, than the single-canister model. From these results, the following are concluded: (1) the new TH code contribute to an additional integrity by estimating TH behavior of KRS; (2) however, due to limitations in single-canister simulation, it is recommended to use multi-canisters simulation to estimate TH behavior accurately. Therefore, this model is anticipated not only to help licensing applications and estimation of various multi-physics phenomena and multi-canister at the disposal site.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.173-178
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• 2007

Time-lapse electrical resistivity measurements have been made in a scale model experiment for geological $CO_2$ sequestration in aquifer. Three types of $CO_2$ injection are tested in a water tank filled with glass beads. These are $CO_2$ dissolved into filtered tap water, $CO_2$ gas, and mineral oil. The mineral oil is a substitute for liquid phase of supercritical $CO_2$. For reconstructing three-dimensional resistivity images, we measure potential differences at 32 potential dipoles on the top surface of the tank due to two current dipoles on the front and back sides. The resultant resistivity images clearly show the movement of injected $CO_2$ in aquifer.

• 터널과지하공간
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• 제30권4호
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• pp.306-319
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• 2020

사용후핵연료의 심층처분 사업에서는 처분장 주변 모암의 수리역학적 성능을 저하시키는 굴착손상영역의 특성화가 중요하다. 이에 DECOVALEX-2019 프로젝트의 Task G에서는 균열암반 수치해석 모델을 구축한 후 암반 주변의 굴착손상영역의 수리역학적 거동을 모사하고, 구축한 모델로 처분장의 운영 시에 장기적으로 야기될 수 있는 추가적인 수리학적 변화를 관찰하였다. 과업의 첫 번째 단계에서는 2차원 균열암반 모델을 구축하여 수치해석 기법의 특성을 파악하고, 두 번째 단계에서는 3차원 균열암반 모델로 확장 후 스웨덴 애스푀 지하연구시설(Äspö Hard Rock Laboratory) 내 TAS04 간섭시험 결과와 비교하여 수치해석 모델을 검증한 후, 세 번째 단계에서는 열과 빙하 하중에 의한 영향을 반영하여 균열암반의 수리역학적 반응을 순차적으로 확인하였다. 과업의 전 과정에서 유한요소법과 개별요소법으로 균열암반에서의 수리역학적 분석을 수행하였으며, 균열의 기하학적 특성을 반영 및 굴착손상영역을 반영하는 과정에서 각 수치해석 기법에 따라 다양한 접근방법으로 고려하였다. 따라서 본 연구는 향후 결정질 균열암반에 사용후핵연료 처분장을 계획할 시 수치해석 단계에서 채택될 수 있는 다양한 접근 방법과 고려해야 할 사항들을 제시할 수 있을 것으로 전망한다.

• Structural Engineering and Mechanics
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• 제23권3호
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• pp.233-247
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• 2006

Most codes of practice state that for large in-plane structures it is necessary to account for the spatial variability of earthquake ground motion. There are essentially three effects that contribute for this variation: (i) wave passage effect, due to finite propagation velocity; (ii) incoherence effect, due to differences in superposition of waves; and (iii) the local site amplification due to spatial variation in geological conditions. This paper discusses the procedures to be undertaken in the time domain analysis of a cable-stayed bridge under spatial variability of earthquake ground motion. The artificial synthesis of correlated displacements series that simulate the earthquake load is discussed first. Next, it is described the 3D model of the International Guadiana Bridge used for running tests with seismic analysis. A comparison of the effects produced by seismic waves with different apparent propagation velocities and different geological conditions is undertaken. The results in this study show that the differences between the analysis with and without spatial variability of earthquake ground motion can be important for some displacements and internal forces, especially those influenced by symmetric modes.

• Geomechanics and Engineering
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• 제8권6호
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• pp.757-767
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• 2015

Rock mass is an important engineering material. In hydropower engineering, rock mass of bank slope controlled the stability of an arch dam. However, mechanical characteristics of the rock mass are not only affected by lithology, but also joints. On the basis of field geological survey, this paper built rock mass material containing parallel concentrated joints with different dip angle, different number under different stress conditions by PFC (Particle Flow Code) numerical simulation. Next, we analyzed mechanical property and fracture features of this rock mass. The following achievements have been obtained through this research. (1) When dip angle of joints is $15^{\circ}$ and $30^{\circ}$, with the increase of joints number, peak strength of rock mass has not changed much. But when dip angle increase to $45^{\circ}$, especially increase to $60^{\circ}$ and $75^{\circ}$, peak strength of rock mass decreased obviously with the increase of joints number. (2) With the increase of confining stress, peak strengths of all rock mass have different degree of improvement, especially the rock mass with dip angle of $75^{\circ}$. (3) Under the condition of no confining stress, dip angle of joints is low and joint number is small, existence of joints has little influence on fracture mode of rock mass, but when joints number increase to 5, tensile deformation firstly happened at joints zone and further resulted in tension fracture of the whole rock mass. When dip angle of joints increases to $45^{\circ}$, fracture presented as shear along joints, and with increase of joints number, strength of rock mass is weakened caused by shear-tension fracture zone along joints. When dip angle of joints increases to $60^{\circ}$ and $75^{\circ}$, deformation and fracture model presented as tension fracture zone along concentrated joints. (4) Influence of increase of confining stress on fracture modes is to weaken joints' control function and to reduce the width of fracture zone. Furthermore, increase of confining stress translated deformation mode from tension to shear.