• Journal of the Korean GEO-environmental Society
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• v.24 no.10
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• pp.15-23
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• 2023

In this study, the infiltration behavior of slopes composed of mixed soils with clay contents of 0%, 5%, and 10% in weathered Gneiss soil, which is a representative weathered soil in Korea, was investigated, and the stability of unsaturated slopes due to rainfall infiltration was examined. For this, in this study, the soil water characteristic curve was obtained through the water retention test, and the strength constant was obtained through the triaxial compression test. Based on the obtained results, the influence of clay content and antecedent rainfall effect (i.e., initial suction) on the formation of saturated zone (i.e., wetting band) and slope stability due to rainfall infiltration was examined through infiltration and stability analyses. As a result, it was found that the hig her the initial suction, the slower the formation of the saturated zone on the slope. In addition, it was found that as the clay content increases, the shear strength of the ground increases and the resistance to rainfall infiltration increases, and eventually the slope stability is greatly improved.

• Membrane and Water Treatment
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• v.10 no.1
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• pp.67-74
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• 2019

Apparent changes in the natural hydrologic cycle causing more frequent floods in urban areas and surface water quality impairment have led stormwater management solutions towards the use of green and sustainable practices that aims to replicate pre-urbanization hydrology. Among the widely documented applications are infiltration techniques that temporarily store rainfall runoff while promoting evapotranspiration, groundwater recharge through infiltration, and diffuse pollutant reduction. In this study, a laboratory-scale infiltration device was built to be able to observe and determine the factors affecting flow variations and corresponding solids removal through a series of experiments employing semi-synthetic stormwater runoff. Results reveal that runoff and solids reduction is greatly influenced by the infiltration capability of the underlying soil which is also affected by rainfall intensity and the available depth for water storage. For gravel-filled structures, a depth of at least 1 m and subsoil infiltration rates of not more than 200 mm/h are suggested for optimum volume reduction and pollutant removal. Moreover, it was found that the length of the structure is more critical than the depth for applications in low infiltration soils. These findings provide a contribution to existing guidelines and current understanding in design and applicability of infiltration systems.

• Journal of the Korean Geotechnical Society
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• v.32 no.1
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• pp.19-33
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• 2016

Stability analysis based on the limit equilibrium method combined with the result of infiltration analysis is commonly used to evaluate the effect of rainfall infiltration on the slope stability. Soil is a three-phase mixture composed of solid particle, water and air. Therefore, a fully coupled mixture theories of stress-deformation behavior and the flow of water and air should be used to accurately analyze the process of rainfall infiltration through soil slope. The purpose of this study is to study the effect of interaction of air and water flow on the mechanical stability of slope. In this study, stability analyses based on the coupled hydro-mechanical model of three-phases were conducted for slope of weathered granite soil widespread in Korea. During the process of hydro-mechanical analysis strength reduction technique was applied to evaluate the effect of rainfall infiltration on the slope stability. The results showed an increase of air pressure during infiltration because rain water continuously displaced the air in the unsaturated zone. Such water-air interaction in the pore space of soil affects the stress-deformation behavior of slope. Therefore, the results from the three-phase model showed different behavior from the solid-water model that ignores the transport effect of air in the pores.

• Journal of Korean Society on Water Environment
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• v.35 no.1
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• pp.72-77
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• 2019

Soil type in LID infiltration practices plays a major role in runoff reduction efficacy. In this study, the effects of infiltration rate of foundation ground under bioretention on annual runoff reduction rate was evaluated using LIDMOD3 which is a simple excel based model for evaluating LID practices. A bioretention area of about 3.2 % was required to capture surface runoff from an impervious area for a 25.4 mm rainfall event. The relative error of runoff from bioretention using LIDMOD3 is 10 % less than that of SWMM5.1 for a total rainfall event of 257.1 mm during the period of Aug. 1 ~ 18, 2017, hence, the applicability of LIDMOD3 was confirmed. Annual runoff reduction rates for the period 2008 ~ 2017 were evaluated for various infiltration rates of foundation ground under the bioretention which ranged from 0.001 to 0.600 m/day and were converted to annual runoff reduction for hydrologic soil group. The runoff reduction rates within hydrologic soil group C and D were steeply increased through increased infiltration rate but not steep within hydrologic A and B with reduction rates ranging from 53 ~ 68 %. The estimated time required to completely empty a bioretention which has a storage depth of 0.632 m is 3.5 ~ 6.9 days and we could assume that the annual average of antecedent rainfall is longer than 3.5 ~ 6.9 days. Therefore, we recommended B type as the minimum hydrologic soil group installed LID infiltration practices for high runoff reduction rate.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.735-738
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• 2005

The purpose of this study is the infiltration characteristics of soil cut-slope by rainfall. Stability analysis of soil cut-slopes has been conducted by limit equilibrium method on Seep/w and finite element method on Slope/w. Result is same as following. First. the hour when seepage line and groundwater in contact is proportionate from rainfall rate condition and upper natural slope gradient condition which is identical. Second, when seepage line and groundwater is contact, seepage line moves gradually at soil cut-slope surface. Finally, seepage line is formed similarly with soil cut-slope gradient. Third, when rainfall is ended, from the recording upper natural slope where the hour will pass it is stabilized

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.553-556
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• 2008

Slope-related disasters have been occurred in July and September due to the typhoon and concentrated precipitation. It is shown that rainfall is the most important factor which leads to slope-related disasters in Korea. In this paper, slope analysis was applied by rainfall intensity as a rain factor and was assumed that all rainfall would be infiltrated on the slope. Also, groundwater level on a slope was estimated by using SEEP/W program according to infiltration. Where, amount of Infiltration can be calculated by using NRCS model. Finally, safety factor on a slope was invested by groundwater level.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.4
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• pp.503-515
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• 2021

In this study, rainfall infiltration in vault of the second near-surface disposal facility was evaluated on the basis of various disposal scenarios. A total of four different disposal scenarios were examined based on the locations of the radioactive waste containers. A numerical model was developed using the FEFLOW software and finite element method to simulate the behavior of infiltrated water in each disposal scenario. The effects of the disposal scenarios on the infiltrated water were evaluated by estimating the flux of the infiltrated water at the vault interfaces. For 300 years, the flux of infiltrated water flowing into the vault was estimated to be 1 mm/year or less for all scenario. The overall results suggest that when the engineered barriers are intact, the flux of infiltrated water cannot generate a sufficient pressure head to penetrate the vault. In addition, it is confirmed that the disposal scenarios have insignificant effects on the infiltrated water flowing into the vault.

• Water for future
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• v.23 no.3
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• pp.351-361
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• 1990

Considering the hydrological los components such as evapotranspiration, interception, surface storage and infiltration, a rainfall excess model for forest watersheds is derived. The Morton model is adopted to estimate the evapotranspration under the wetted environmental conditions. Canopy effects and ground cover interception storage rates are used to determine the net rainfall rates arrived on the surface soil. The infiltration capacity on the permeable surface is estimated from the revised Green-Ampt model derived for the natural unsteady rainfall events. The rainfall excess model derived is applied with the data from Jangpyung watershed, one of the representative watersheds of IHP. Parameters which are calibrated with the data from ten storms, the hydrometeorological, land use and soil informations, and other researchers' papers are presented.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.130-130
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• 2021

The increasing effect of urbanization has been more apparent through flooding and downstream water quality especially from heavy rainfalls. In response, stormwater runoff management solutions have focused on runoff volume reduction and treatment through infiltration. However, there are areas with low infiltration soils or are experiencing more dry days and even drought. In this study, a lab-scale infiltration system was used to compare the applicability of two types of soil as base layer in gravel-filled infiltration systems with emphasis on runoff capture and suspended solids removal. The two types of soils used were sandy soil representing a high infiltration system and clayey soil representing a low infiltration system. Findings showed that infiltration rates increased with the water depth above the gravel-soil interface indicating that the available depth for water storage affects this parameter. Runoff capture in the high infiltration system is more affected by rainfall depth and inflow rates as compared to that in the low infiltration system. Based on runoff capture and pollutant removal analysis, a media depth of at least 0.4 m for high infiltration systems and 1 m for low infiltration systems is required to capture and treat a 10-mm rainfall in Korea. A maximum infiltration rate of 200 mm/h was also found to be ideal to provide enough retention time for pollutant removal. Moreover, it was revealed that low infiltration systems are more susceptible to horizontal flows and that the length of the structure may be more critical that the depth in this condition.

• Journal of Korean Society on Water Environment
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• v.25 no.3
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• pp.411-418
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• 2009

The analysis of characteristics of water use evaluation and nighttime domestic flow evaluation was performed by using result from flow monitoring and surveying water supply records and nighttime domestic flow for a year. The analysis of correlations showed that, for both sites, the infiltration ratio and wastewater flow have shown a good relationship with high correlation factor and that the calculation of wastewater flow was highly affected by monthly rainfall depth as well as number of rain days. From this result, it was concluded that the measurement of infiltration should be performed when the rainfall does not significantly affect the sewer flow. Also, it is notable that each value of calculated using method for infiltration evaluation are not comparable to each other, but independent methods. In selecting of evaluation method for infiltration, therefore, a great emphasis should be imposed to the character of area and the seasonal factor in order to select optimal one. It is desirable way for evaluating infiltration and reduction ratio using result from an optimal method.