• Ocean and Polar Research
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• v.25 no.1
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• pp.75-87
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• 2003

The water balance calculation in the IRL shows that fresh groundwater discharge is the primary factor, with surface runoff from gaged and ungaged areas as the second freshwater contributor. Precipitation and evaporation are almost in balance fer the entire IRL. Due to high freshwater discharge from ground-water, the annual net flow is outward from the IRL to the continental shelf of the Atlantic Ocean resulting in a relatively short flushing time, denoted as $T_{0.5}$ (50% flushing time) and $T_{0.99}$ (99% flushing time). $T_{0.5}$, and. $T_{0.99}$ without a tidal effect in the Northern IRL are 17 and 114 days, respectively, during the dry season. During the wet season, they are 10 and 65 days, respectively. Tidal flushing effects are considered in central IRL due to the proximity to Sebastian Inlet. In the Northern Central zone during dry season, $T_{0.5}$, and. $T_{0.99}$ are 6 and 43 days, respectively and during the wet season 5 and 33 days. In the Southern Central zone they are 2 and 16 days for the dry season,2 and 15 days for the wet season. High groundwater seepage into the IRL is considered to be a positive effect in maintaining relatively good water quality condition even with few narrow inlets.

• Proceedings of the Korean Geotechical Society Conference
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• 1993.03a
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• pp.49-58
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• 1993

Reappraisal of the design and the construction concept of the bottom drainage tunnel has been made through the seepage analysis. An appropriate design approach for this tunnel has also been proposed. It was revealed from this study that water pressures acting on the concrete lining in the bottom dralnage tunnel much depend on the permeability of the surrounding ground, the source of water supply and the discharge capacity of dralnage facilities. The full release of these water pressures by the current drainage system could not be expected if this type of tunnel is constructed in the ground including alluvial deposits having a high permeability. The necessity of a proper reinforcement of the concrete lining or a modification of its shapes corresponding to the water pressure has been suggested.

• Journal of the Korean GEO-environmental Society
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• v.21 no.9
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• pp.5-14
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• 2020

This study analyzed the reinforcement effect by conducting laboratory test, model test and program analysis to utilize the surface stabilizer used for the restoration work of collapsed slopes as a reinforcing material for aging reservoirs that exhibits a curing reaction similar to cement. Based on the results of the laboratory test, a model test and program analysis were performed by applying 9% of the mixing ratio. As a result, when the surface stabilizer was used in aging reservoir, it was found that the flow of water only occurred on part of the slope and underground in reservoir. And the water flow could be reduced inside the reservoir. In addition, it was analyzed that the seepage discharge could be reduced by about 42% and the saturated area within the reservoir by about 73%, thereby securing the stability of the aged reservoir.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.6
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• pp.67-72
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• 2019

This study compared the theory of a culvert spacing and analytical results of the seepage flow for the subsurface drainage. i) If culvert spacing (Sc) is within 5 m, the unit drainage (q) is very larger; in contrast, if Sc is 5 m or more, there is very little drainage in the middle between drains. Therefore, the drain spacing should be within 5 m to ensure high drainage efficiency. ii) Since the planned culvert drainage increases linearly with the soil's permeability coefficient (k), k must be taken into account when determining the drain diameter by the planned culvert drainage. iii) As a result of analyzing the drainage performance of the absorbing culvert, the drainage performance is sufficient with the diameter of the corrugated drain pipe Dc = 50 mm at the length of the drain Lc = 100 m. iv) Therefore, if the drain spacing (Sc) is less than 5 m using the low-cost non-excavated drainage pipe method (${\Phi}50mm$ the corrugated drain pipe and fiber mat) rather than the conventional trench drain method (Sc > 10 m, Dc > 100 mm), uniform and high drainage efficiency can be ensured as well as low construction cost. v) The sub-irrigation+drainage culvert requires narrower drain spacing (Sc < 2-3 m) for irrigation. As a result of examining the condition of 35 mm in diameter (Dc) and 2~3 m in drain spacing, it is possible to apply the non-excavated drainage pipe method to the sub-irrigation+drainage culvert because drainage performance is sufficient at the drain length Lc = 50 m.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.3 no.1
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• pp.52-61
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• 2000

Permeability is important factor in the geotechnical problems, such as seepage discharge and dissipation of excess pore water pressure. The Kozeny-Carman equation works well for graded soils but serious discrepancies are found in clays. Major factor for these discrepancies is the tortuous flow path and unequal pore size. To estimate the permeability of fine grained soils, a permeability equation in which swelling potential is coupled with Kozeny-Carman equation is proposed in this study. To verify proposed equation, a series of variable head permeability test was carried out for steel making slag and sludge mixed with bentonite. The coefficients of permeability which is measured in the laboratory is compared with the values by the proposed equation. From the comparison, it is shown that the proposed equation can predict the coefficient of permeability of clays with satisfaction. As steel making slag and sludge is industry waste, it is reused as material of road foundation and cement but the rate of use is low. It mixed sodium-bentonite with high swelling property and permeability decrease effect. Then, Admixture investigates reuse possibility as liner of waste fill.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.424-433
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• 2006

This paper studies the field applicability of the Special Chemical grouting Method(SCM) in reinforcing and reducing permeability of the back of an existing continuous wall. SCM uses double rod which imposes intermediate pressure$(981\sim9,810kPa)$ to disturb, cut, discharge, and mix the ground. It is observed that a bulb is formed by using cement paste and environmentally friendly injection materials with minimal alkali leaching. Uniaxial compression tests, test for chemical properties and fish poison test are performed. Test results indicate that the method results in higher durability, less leaching through use of the environmentally friendly injection material, and faster mobilization of the strength. In addition, field tests confirm the formation of the bulb and the seepage cutoff wall.

• Journal of the Korean Geotechnical Society
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• v.22 no.12
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• pp.25-31
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• 2006

This paper studies the field applicability of the Special Chemical grouting Method (SCM) in reinforcing and reducing permeability of the back of an existing continuous wall. SCM uses double rod which imposes intermediate pressure ($981{\sim}9,810kPa$) to disturb, cut, discharge, and mix the ground. It is observed that a bulb is formed by using cement paste and environmentally friendly injection materials with minimal alkali leaching. Uniaxial compression tests, test for chemical properties and fish poison test are performed. Test results indicate that the method results in higher durability, less leaching through the use of the environmentally friendly injection material and faster mobilization of the strength. In addition, field tests confirm the formation of the bulb and the seepage cutoff wall.

• Economic and Environmental Geology
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• v.42 no.6
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• pp.599-608
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• 2009

This study was conducted to examine chemical characteristics and correlations among seepage water, subsurface waters and inland groundwater in and around a coastal underground LPG cavern using factor and cluster analyses. The study area is located in western coast of Incheon metropolitan city and is about 8 km off the coast. The LPG cavern storing propane and butane was built beneath artificially reclaimed island. Mean bathymetry is 8.5 m and maximum sea level change is 10 m. Water sampling was conducted in May and August, 2006 from 22 sampling points. Correlation analysis showed strong correlations among $Fe^{2+}$ and $Mn^{2+}$ (r=0.83~0.99), and Na and Cl (r=0.70~0.97), which indicated reductive dissolution of iron and manganese bearing minerals and seawater ingression effect, respectively. According to factor analysis, Factors 1 (May) and I (August) showed high loadings for parameters representing seawater ingression into the cavern and effect of submarine groundwater discharge, respectively while Factors 2 and IV showed high loadings for those representing oxidation condition (DO and ORP). Factors 4 and II have large positive loadings for $Fe^{2+}$ and $Mn^{2+}$. The increase of $Fe^{2+}$ and $Mn^{2+}$ was related to decomposition of organic matter and subsequent their dissolution under reduced condition. Cluster analysis showed the resulting 6 groups for May and 5 groups for August, which mainly included groups of inland groundwater, cavern seepage water, sea water and subsurface water in the LPG storage cavern. Subsurface water (Group 2 and Group III) around the underground storage cavern showed high EC and major ions contents, which represents the seawater effect. Cavern seepage water (Group 5 and Group II) showed a reduced condition (low DO and negative ORP) and higher levels of $Fe^{2+}$ and $Mn^{2+}$.

• Journal of Korea Water Resources Association
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• v.48 no.3
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• pp.149-158
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• 2015

It is well known that emergency outlet works have to be provided for the safety of dams. However, concept of emergency outlet works did not applied for the design of the most dams in Korea. Korean design standard for low-level outlet works does not provide enough design criteria which could be used in design of emergency outlet works. In this research, as-built status and hydraulic design criteria of outlet works, such as drawdown rate or hydraulic pressure due to the impounded water depth, were examined. Another relationship between drawdown rate and the dam slope stability was also examined with SEEP model. It was found that 25% reduction of impounded water depth decreases the pressure forces about 50%. Therefore, outlet works should be designed to drawdown properly at the beginning of the emergency. Seepage analysis of dam bodies showed that most of Korean dams could safely stand for 1m/day drawdown rate. Higher drawdown rate could result high discharge so the drawdown rate must be related with the flood risk of downstream. Finally, multi-stage design was recommended that faster discharge for the initial 25% of water depth in 7-10 days than the rest of it in 1-2 months.

• Journal of Korean Society of Disaster and Security
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• v.17 no.2
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• pp.1-11
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• 2024

Most reservoirs in South Korea are earthen dams, mainly because they are cost-effective and easy to construct. However, earthen dams are highly vulnerable to seepage and overtopping, making them prone to sudden failure during excessive flooding. Such sudden failures can lead to a rapid increase in flood discharge, causing significant damage to downstream rivers and inhabited areas. This study investigates the effect of riprap placement on the slopes of earthen dams in delaying dam failure. Delaying the failure time is crucial as it allows more time for evacuation, significantly reducing potential casualties, which is essential from a disaster response perspective. Hydraulic experiments were conducted in a straight channel, using two different sizes of riprap for protection. Unlike previous studies, these experiments were performed under unsteady flow conditions to reflect the impact of rising water levels inside the dam. The target dam for the study was a cofferdam installed in a diversion tunnel. Experimental results indicated that the presence of riprap protection effectively prevented slope failure under the tested conditions. Without riprap protection, increasing the size of the riprap delayed the failure time. This delay can reduce peak discharge, mitigating damage downstream of the dam. Furthermore, these findings can serve as critical reference material for establishing emergency action plans (EAP) for reservoir failure.