• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1727-1734
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• 2008

After the final closure of sea dyke, seepage behaviour of embankment is highly changed by variation of water head different between tide wave and controlled water level at fresh lake. Especially, the seepage behaviour of bottom protection layer of final closure section is more important factor for structural and functional stability of sea dyke, because of the bottom protection layer of final closure section is penetrated sea side to fresh lake. Even though bottom protection layer was filled with dredged fine sand, it has a high permeability. In this paper, mainly described about the seepage velocity and borehole image of bottom protection layer filled with dredged sand after final closure. Various in-situ tests such as BIPS (Borehole Image Processing System) and ABI (Acoustic Borehole Imager) survey, wave velocity measuring, and color tracer survey were conducted to evaluate the seepage behavior of bottom protection layer. Based on the in-situ tests, the bottom protection layer of final closure section was almost filled with dredged sand which is slightly coarse grain sand and there have sea water flow by water head different between tide wave and controlled water level at fresh lake. Also, comply with tracer survey results, the sea water flow path was not exist or generated in the bottom protection layer. However, because of this result not only short term survey but also just one test borehole survey results, additional long term and other borehole tests are needed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 가을 학술발표회 논문집
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• pp.193-200
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• 1999

Since Broms and Bennermark(1967) suggested the face stability criterion based on laboratory extrusion tests and field observations, the face stability of a tunnel driven in cohesive material has been studied by several authors. And recently, more general solution for the tunnel front is given by Leca and Panet(1988). They adopted a limit state design concept to evaluate the face stability of a shallow tunnel driven into cohesionless material and showed that the calculated upper bound solution represented the actual behavior reasonably well. In this study, two factors are simultaneously considered for assessing tunnel face stability: One is the effective stress acting on the tunnel front calculated by upper bound solution; and the other is the seepage force calculated by numerical analysis under the condition of steady state ground water flow. The model tests were performed to evaluate the seepage force acting on the tunnel front and these results were compared with results of numerical analysis. Consequently, the methodology to evaluate the stability of a tunnel face including limit analysis and seepage analysis is suggested under the condition of steady state ground water flow.

• 한국농공학회지
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• 제19권2호
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• pp.4417-4422
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• 1977

This thesis is a result of theoretical and electrical experimental studies for the shape of Seepage on various Earth Dams. The decrement method of seepage through of water amount to earth Dam's was tested by means of experiment by the model constructed in the water tank. A study of the seepage through earth Dam's is necessary for a satisfactory of the same. An attempt was made in these investigations to study the problem of the seepage through homogeneous earth dams with filters located near the axis of the dam and filters extending in to upstream portion of the dam by the electrical analogy method. The experimental results were at variance with the graphical solution given by A Casagrande method. Some of the results were checked by relaxation method and by the circle criterion for drawing flow nets.

• 한국지반환경공학회 논문집
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• 제16권6호
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• pp.39-43
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• 2015

This study extends the Distributed Temperature Sensing (DTS) application to delineate the saturated zones in shallow sediment and evaluate the groundwater flow in both downward and upward directions. Dry, partially and fully saturated zones and water level in the subsurface can be recognized from this study. High resolution seepage velocity in vertical direction was estimated from the temperature data in the fully saturated zone. By a single profile, water level can be detected and seepage velocity in saturated zone can be estimated. Furthermore, thermal gradient analysis serves as a new technique to verify unsaturated and saturated zones in the subsurface. The vertical seepage velocity distribution in the recognized saturated zone is then analyzed with improvement of Bredehoeft and Papaopulos' model. This new approach provides promising potential in real-time monitoring of groundwater movement.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 추계 학술발표회
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• pp.179-190
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• 2006

The water supply tunnel has different characteristics which play a important role in stable water supply to the public from mechanical behavior and maintenance in comparison with road md railway tunnel. In this study, the present state and characteristics of water supply tunnels controlled by K-water have been investigated. The distribution of effective stresses that takes into account the effect of seepage forces induced by internal water pressure are estimated from closed-form and numerical method. The analysis of stress-strain behavior, seepage problem and hydrojacking for ensuring safety of existing water supply tunnel against neighboring new construction has been conducted.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2012년도 학술발표회
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• pp.34-34
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• 2012

Heavy storms rainfall has caused many landslides and slope failures especially in the mountainous area of the world. Landslides and slope failures are common geologic hazards and posed serious threats and globally cause billions in monetary losses and thousands of casualies each year so that studies on slope stability and its failure mechanism under rainfall are being increasing attention of these days. Rainfall-induced slope failures are generally caused by the rise in ground water level, and increase in pore water pressures and seepage forces during periods of intense rainfall. The effective stress in the soil will be decreased due to the increased pore pressure, which thus reduces the soil shear strength, eventually resulting in slope failure. During the rainfall, a wetting front goes downward into the slope, resulting in a gradual increase of the water content and a decrease of the negative pore-water pressure. This negative pore-water pressure is referred to as matric suction when referenced to the pore air pressure that contributes to the stability of unsaturated soil slopes. Therefore, the importance is the study of saturated unsaturated soil behaviors in evaluation of slope stability under heavy rainfall condition. In an actual field, a series of failures may occur in a slope due to a rainfall event. So, this study attempts to develop a numerical model to investigate this failure mechanism. A two-dimensional seepage flow model coupled with a one-dimensional surface flow and erosion/deposition model is used for seepage analysis. It is necessary to identify either there is surface runoff produced or not in a soil slope during a rainfall event, while analyzing the seepage and stability of such slopes. Runoff produced by rainfall may result erosion/deposition process on the surface of the slope. The depth of runoff has vital role in the seepage process within the soil domain so that surface flow and erosion/deposition model computes the surface water head of the runoff produced by the rainfall, and erosion/deposition on the surface of the model slope. Pore water pressure and moisture content data obtained by the seepage flow model are then used to analyze the stability of the slope. Spencer method of slope stability analysis is incorporated into dynamic programming to locate the critical slip surface of a general slope.

• 한국해안해양공학회지
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• 제6권4호
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• pp.397-403
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• 1994

레이놀즈수에 대한 투수층흐름 마찰계수의 관계식을 개발하고자 투수층수조 실험을 실시하였다. 사용된 투수층수조는 물이 거의 수평으로 흐르도록 유도하는 장치이다. 각 구간마다 수두의 변화로 한번의 실험으로 다양한 수리조건을 재현할 수 있는 포괄성을 갖고 있으며, 여러 조의 수리실험을 실시하였다. 보다 광범위한 수리조건을 재현하기 위하여 여러 크기의 골재를 사용하였고 유출량도 다양하게 송출하였다. 기존자료를 이용하여 형상계수 산정식을 개발하였으며, 금번 수조실험의 결과를 이용하여 레이놀즈수가 1부터 600까지의 조건에서 투수층흐름 마찰계수를 구하는 양해법 산정식을 개발하였다. 관측된 마찰계수의 분포경향을 고려하였을 때, 레이놀즈수가 600보다 큰 난류조건에서도 동일 산정식을 사용할 수 있으리라 기대된다.

• Geomechanics and Engineering
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• 제32권2호
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• pp.145-157
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• 2023

This paper aims at investigating the face stability of large-diameter underwater shield tunnels considering seepage in soft-hard uneven strata. Using the kinematic approach of limit upper-bound analysis, the analytical solution of limit supporting pressure on the tunnel face considering seepage was obtained based on a logarithmic spiral collapsed body in uneven strata. The stability analysis method of the excavation face with different soft- and hard-stratum ratios was explored and validated. Moreover, the effects of water level and burial depth on tunnel face stability were discussed. The results show the effect of seepage on the excavation face stability can be accounted as the seepage force on the excavation face and the seepage force of pore water in instability body. When the thickness ratio of hard soil layer within the excavation face exceeds 1/6D, the interface of the soft and hard soil layer can be placed at tunnel axis during stability analysis. The reliability of the analytical solution of the limit supporting pressure is validated by numerical method and literature methods. The increase of water level causes the instability of upper soft soil layer firstly due to the higher seepage force. With the rise of burial depth, the horizontal displacement of the upper soft soil decreases and the limit supporting pressure changes little because of soil arching effect.

• 한국지반공학회논문집
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• 제25권9호
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• pp.101-106
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• 2009

본 연구에서는 국내 지형에 따른 하천 특성을 고려하여 하천제방구간 만곡부의 침투특성을 분석하였으며, 하천제방의 직선부 및 만곡부를 구분하여 보다 실제적인 침투해석이 실시 되도록 하였다. 제방만곡부 침투 특성 반영에 적합하도록 평면선형각도를 $90^{\circ}$, $130^{\circ}$로 변화시켰고, 평수위 및 홍수위 조건과 투수계수 등의 매개변수를 변화시켜가며 침투해석을 수행하였다. 침투해석은 보다 상세하고 정밀하게 만곡부 형상의 침투 해석 흐름을 나타낼 수 있는 3차원 수치해석 프로그램인 VisualFEA로 수행하였다. 평수위 및 홍수위시의 침투 해석결과 직선부에서는 투수계수와 관계없이 동일 수위형태로 나타났으며 만곡부로 근접할수록 침윤선이 중첩되면서 수두가 증가하였다. 만곡부의 평면 선형 $90^{\circ}$, $130^{\circ}$ 의 경우 평면선형각이 $90^{\circ}$에서 수두증가 현상이 더 크게 나타났으며, 직선부에서는 모두 비슷한 양상을 보였다.

• 한국지반공학회논문집
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• 제22권4호
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• pp.73-83
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• 2006

댐 안정성 평가를 위하여 불포화 이론을 이용한 침투해석 기법이 널리 사용되고 있으나 지반의 불포화 거동에 대한 인식 부족과 실험절차의 번거로움으로 인하여 입력 물성치에 대한 체계적인 실험과 평가가 일반화되지 못하고 있는 실정이다. 지반의 불포화 수리특성은 변동성과 불확실성을 내포하고 있으며, 이는 침투수량 및 간극수압 분포 등 댐체 및 제방의 침투거동에 영향을 미친다. 본 연구에서는 댐의 심벽재료에 대한 함수특성곡선과 투수계수를 구하는 실내실험을 수행하였다. 그리고, 불포화수리특성이 댐체의 침투 거동에 미치는 영향을 살펴보기 위하여 입력물성의 확률론적 분포를 고려한 수치해석을 수행하였다. 해석결과 Fredlund와 Xing 함수특성곡선식과 Campbell의 투수계 수식에서 변수 a와 n은 값이 클수록, n과 p는 값이 작을수록 정상상태에서의 침투수량이 많았다.