• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
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• pp.232-236
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• 2005

In-situ Air Sparging (IAS, AS) is a groundwater remediation technique, in which organic contaminants are volatilized into air as it rises from saturated to vadose soil zone. The purpose of this study was to investigate the effect of environmental conditions on the degradation of VOCs (Volatile Organic Compounds) and $CO_2$ in the unsaturated zone and TPH (Total Petroleum Hydrocarbons) in saturated zone of sandy loam. In the laboratory, diesel (10,000 mg TPH/kg)-contaminated saturated soil. After heating the soil for 36 days, the equilibrium temperature of soil reached to $34.9{\pm}2.7^{\circ}C$ and TPH concentration was reduced to 78.9% of the initial value, Volatilization loss of VOCs in TPH was about 2%, The reduction gradient of $CO_2$ concentration was 0.018/day in air space and 0.0007/day in unsaturated zone.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.213-217
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• 2004

Laboratory scale study for an area of influence and flowing aspect of groundwater saturated zone was conducted for three sediment grains. On the AMG(Average Modal diameter Grains) 0.34, 1.38, 3.89mm diameter samples, the affected area of the aquifer were 15.2, 37.0, 30.0%/m2 each. Air flow for AMG 0.34mm diameter grain size provides indication of pattern of channelized air flow in saturated zone and expansion state in above saturated zone. For AMG of 1.38, 3.89mm diameter grains, air flow are pervasive air flow, forming a symmetrical cone of influence around the injection point. And also AMG 1.38, 3.89mm diameter samples show onset of collapse and approach to steady state in above saturated zone, respectively. In this study, optimal sites for in situ air sparging, may be grain diameters between about AMC 1.5～2.5mm diameter.

• 한국물환경학회지
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• 제23권5호
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• pp.665-675
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• 2007

In-situ Air Sparging (IAS, AS) is a remediation technique in which organic contaminants are volatilized from saturated zone to unsaturated layer. This study focuses on the removal and interaction of Volatile Organic Compounds (VOCs) and $CO_2$, and Total Petroleum Hydrocarbon (TPH) in saturated and unsaturated, and air space zone on the unsaturated soil surface. Soil sparging temperature of hot air has risen to $34.9{\pm}2.7^{\circ}C$ from $23.0{\pm}1.9^{\circ}C$ for 36 days. At the diffusing point, fluid TPH concentrations were reduced to 78.7% of the initial concentration in saturated zone when hot air was sparged. The TPH concentrations were decreased to 66.1% for room temperature air sparging. The amount of VOCs for hot air sparging system, in air space, was approximately 26% larger than constant air sparging system. The amount of $CO_2$ was 4,555 mg (in unsaturated zone) and 4,419 mg (in air space) when hot air was sparged was 3,015 mg (in unsaturated zone) and 3,634 mg (in air space) for room air temperature in the $CO_2$ amount. The removals of VOCs and biodegradable $CO_2$ through the hot air sparging system (modified SVE) were more effective than the room temperature air sparging. The regression equation were $Y=976.4e^{-0.015{\cdot}X}$, $R^2=0.98$ (hot air sparging) and $Y=1055e^{-0.028{\cdot}X}$, $R^2=0.90$ (room temperaure air sparging). Estimated remediation time was approximately 500 days, if final saturated soil TPH concentration was set to 1.2 mg/L application of tail effect.

• Geomechanics and Engineering
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• 제30권6호
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• pp.579-586
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• 2022

Pile-supported structures are installed on saturated sloping grounds, where the ground stiffness may decrease due to liquefaction during earthquakes. Thus, it is important to consider saturated sloping ground and pile interactions. In this study, we conduct a centrifuge test of a pile-supported structure, and analyze the p-y_p loops, p-y_p loops provide the correlation between the lateral pile deflection (y_p) and lateral soil resistance (p). In the dry sand model (UV67), the p-y_p loops stiffness increased as ground depth increased, and the p-y_p loops stiffness was larger by approximately three times when the pile moved to the upslope direction, compared with when it moved to the downslope direction. In contrast, no significant difference was observed in the stiffness with the ground depth and pile moving direction in the saturated sand model (SV69). Furthermore, we identify the unstable zone based on the result of the lateral soil resistance (p). In the case of the SV69 model, the maximum depth of the unstable zone is five times larger than that of the dry sand model, and it was found that the saturated sand model was affected significantly by kinematic forces due to slope failure.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2000년도 창립총회 및 춘계학술발표회
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• pp.129-132
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• 2000

In this research, we proposed the immobilization zone where the organic contaminant would be fixed, so that ground water could be prevented from the organic contaminants. The surfactant was adsorbed on the soil particles and the organic contaminants were partitioned into the hydrophobic tails of the surfactant in the immobilization zone. Surfactants with different molecular structures-SDDBS (sodium dodecylbenzenesulfonic acid), MADS (monoalkylated disulfonated diphenyl oxide), DADS (dialkylated disulfonated diphenyl oxide) - were used in this study. Up to the present, the research on the immolization simulated the saturated condition. But many site contaminated with organic contaminants and the zones where immobilization would be applied are unsaturated. In this research, in order to investigate the behaviors of surfactants and organic contaminants in unsaturated condition, the unsaturated columns were experimented, and their results were compared with the saturated case.

• 한국지하수토양환경학회지:지하수토양환경
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• 제11권4호
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• pp.48-56
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• 2006

여러 개의 층으로 구성된 토양층에서 연속주입 추적자시험을 수행하여, 불포화대와 포화대 구간에서의 수리분산특성 차이를 추적자의 농도이력곡선, 시간에 따른 농도변화 및 농도변화율, 그리고 거리에 따른 농도비 분석을 통해 비교 연구하였다. 연속주입 추적자시험에 의하면, 약 160시간이 경과된 후에 불포화대와 포화대에서 Rhodamine WT 최대농도의 차이는 약 $13{\sim}15$배 정도에 달하였고, 시험시간 대 추적자 농도증가율의 차이는 약 10배 정도로 나타났다. 또한 시간에 따른 추적자 농도이력곡선의 변화와 농도변화율이 불포화대에 비하여 포화대에서 크게 나타났다. 주입공에서의 이격거리에 따른 추적자의 농도비는 포화대 구간에서 더 빠르게 선형적으로 감소하였으며, 그 이후에 농도비가 2배 이하로 완만해 지는데 걸린 시간은 포화대 구간이 더 길었다. 이러한 차이들은 여러 개의 층서로 구성된 토양층의 포화대에서는 지하수가 존재하며, 또한 매질의 불균질성이 크고 투수성이 다양하기 때문에, 비교적 균질한 층서를 이루는 불포화대에 비하여 추적자 용액의 농도는 낮고, 추적자의 확산이 느리게 진행되어진데서 기인하였다. 그리고 포화대 구간에서의 유효공극율은 $10.19{\sim}10.50%$, 종분산지수는 $0.80{\sim}l.98m$, 횡분산지수는 $0.02{\sim}0.04m$의 범위로 산정되었으며, 실내주상시험의 종분산지수와 비교할 때 12배 이상의 규모종속효과가 나타났다.

• 물과 미래
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• 제22권3호
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• pp.289-298
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• 1989

A review is made of transient phenomena ralation to flow in the vadose zone. Reviewed topics include rapid water table response to rainfall, pulsating flow due to pressure perturbations in the vasoes zone, and the wave-like propagation of increased soil moisture caused by intermittent rainfall. As a basis of interpreting these phenomena, zoning of the vadose zone into a residual water zone, an unsaturated capillaty zone, and a saturated capillary zone are proposed. Possible implications with respect to hydrological processes relating to these phenomena are discussed.

• Geomechanics and Engineering
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• 제28권1호
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• pp.77-87
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• 2022

Many geotechnical analyses require the investigation of water flow within partially saturated soil zone to incorporate the effect of climatic conditions. It is widely understood that the hydraulic properties of the partially saturated soil should be included in the transient seepage analyses. However, the characteristics of dual porosity soils with dual-mode water retention curve are normally modelled using single-mode mathematical equation for simplification of the analysis. In reality, the rainwater flow can be affected significantly by the dual-mode hydraulic properties of the soil. This paper presents the variations of safety factor for dual porosity soil slope with dual-mode water retention curve and dual-mode unsaturated permeability. This paper includes the development of the new dual-mode unsaturated permeability to represent the characteristics of soil with the dual-mode water retention curve. The finite element analyses were conducted to examine the role of dual-mode water retention curve and dual-mode unsaturated permeability on the variations of safety factor under rainfall loading. The results indicate that the safety factor variations of dual porosity soil slope modelled using the dual-mode water retention curve and the unsaturated permeability equation are lower than those of dual porosity slope modelled using single-mode water retention curve and unsaturated permeability equations.

• 한국지하수토양환경학회지:지하수토양환경
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• 제8권3호
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• pp.13-22
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• 2003

현장공기분사공정의 복원효율에 있어서 중요한 인자로 작용 할 수 있는 것은 공기가 지하 포화대수층을 통과하면서 생기는 공기분사에 따른 흐름 양상과 토양입자크기에 따른 공기의 영향반경이다. 토양입자크기별 AMG 0.34, 1.38, 3.89 mm diameter 3가지 입자크기로 실험한 결과 AMG 0.34 mm diameter의 포화 대수층에서는 공기가 처음 결정된 방향으로만 흐르는 채널링 현상(channelized air flow)과 포화 대수층 가장 윗면에서는 확장모양(expansion state)을 가졌으며, 공기영향반경은 단위 면적당 15.2%/$\textrm{m}^2$이었다. AMG 1.38, 3.89 mm diameter의 포화 대수층에서는 공기가 퍼지는 현상(pervasive air flow)과 포화 대수층 가장 윗면에서는 각각 붕괴의 조짐(onset of collapse), 안정한 상태로 퍼짐모양(approach to steady state)을 가졌으며, 단위면적당 각각 37.0%/$\textrm{m}^2$, 30.0%/$\textrm{m}^2$영향반경이 계산되었다. 이 실험을 통해서 현장공기분사공정에 있어서 토양입자 크기에 따른 최대 영향반경효율을 얻을 수 있는 토양입자의 크기는 AMG 1.5-2.5 mm diameter로 사료된다.

• 생명과학회지
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• 제24권5호
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• pp.543-548
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• 2014

대수층 함양 및 회수(Aquifer recharge and recovery)기술은 안정적으로 안전한 상수원수를 확보하기 위해 이용되는 기술의 하나이다. 이 기술을 통해 대수층에 하천수를 인위적으로 주입하여 저장하고 필요할 때 퍼 올려 상수 원수로 사용할 수 있다. 이 기술에서 주입된 물이 저장되는 동안 대수층의 토착미생물에 의해 수질이 개선되는 것을 이해하는 것은 중요하다. 그래서 본 연구에서는 실험실규모의 컬럼 반응기를 이용하여 대수층을 모사한 포화층 토양에 존재하는 미생물에 의한 $NO_3{^-}$ 제거를 조사하였다. $NO_3{^-}$는 낙동강의 대표적인 무기 오염물 중의 하나이다. 낙동강 하류에서 최근 2년간 측정된 $NO_3{^-}$ 농도 범위를 고려해서 $NO_3{^-}$ 농도를 달리한 하천수를 반응기에 주입하였다: 5.07, 6.81, 8.27, 그리고 11.07 mg $NO_3{^-}/l$. 본 연구에서 사용한 다양한 $NO_3{^-}$농도에 상관없이 유입수가 반응기에 체류하는 동안 $NO_3{^-}$는 농도가 감소되어 유출수는 1.49 mg $NO_3{^-}/l$이하로 측정되었으며 본 실험기간 동안 평균 pH 7.98을 유지하였다. 한편 abiotic control 반응기에서는 유입수에 포함된 $NO_3{^-}$ 농도와 유출수의 $NO_3{^-}$ 농도는 거의 차이가 없었다. 그래서 본 실험조건하에서 반응기로 도입된 하천수의 $NO_3{^-}$이 포화층의 미생물에 의해 제거됨을 알 수 있었다. 본 연구에서 도출된 결과는 대수층 함양 및 회수기술에서 대수층의 미생물에 의해 수질이 개선되는 것을 이해하는 데 도움을 줄 것이다.