• Journal of the Korean Geotechnical Society
• /
• v.21 no.6
• /
• pp.137-146
• /
• 2005

299 railroad slopes were investigated and the failure characteristics and reinforcement patterns were analyzed. Stability analyses on the 14 cut-off soil slopes were carried out. Surficial failures were predicted by infinite slope analyses assuming the temporarily perched ground water table at soil surface during rainfall period. Limit equilibrium analyses were also carried out and the influences of rainfall infiltration on the slope stabilities were taken Into account by seepage analyses using finite element method and by assuming ground water tables to be located adjacent to soil surface. The adequacy of those analyses was evaluated by comparing the slope failure characteristics between analysis results and the past failure records. From the comparison results, it was deduced that the limit equilibrium analyses were not appropriate to estimate the shallow failure that occurred at most of the railroad cut-off soil slopes. For the better estimation of the surficial failure, not only the increase of pore-water pressure (reduction of matric suction), but also the influence of water flows over slope surface which erode soil mass, should be evaluated and considered.

• Journal of Korea Water Resources Association
• /
• v.30 no.1
• /
• pp.23-34
• /
• 1997

The Nanji-Do ladnfill is an ill-conditioned reclaimed land without pollution intercepting facilities, and has high ground water table and deep stratum. The purpose of this study is to analyze the solute transport in steady-state groundwater flow and to predict the solute dispersion in Nanji-Do landfill using HST-3D model. As results, the groundwater flows radially outward from the center of No. 1 and No. 2 landfills, and large amount of runoff is moved into Han River. The predicted relative concentration of total dissolved solute(TDS) at two years later was 0.25 in the weathering zone, 0.26 in the lower alluvium, and 0.28 in the upper alluvium. Thus, the further pollution to bottom rock and Han River was predicted by comparing the corresponding present values of 0.29, 0.32 and 0.35.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.19 no.1
• /
• pp.4323-4337
• /
• 1977

The study was to estimate the effect of the rise of water temperature in the warm water pool and to make contribution to the establishment of reducing to a damage of cool water as well as to the planning for warm water pool. This observation was performed in Wudu warm water pool located at Wudu-Dong of Chuncheon for two years from 1975 to 1976. The results were showed as follows; 1. The daily variation of water temperature was the least for inset (No.1; 0.6$^{\circ}C$) the second for middle overflow (No2: 3$^{\circ}C$, No.3; 2.3$^{\circ}C$) and another for outflet (No.4; 3.6$^{\circ}C$, No.5; 3.8$^{\circ}C$) And the highest reaching time of water temperature in each block was later about 1 hour than the time at which air temperature happend in the daytime. So, the variation of water temperature was sensitive to the variation of air temperature 2. The monthly variation of water temperature at each measuring point was plotted to be increased with increase in air temperature till August (Mean monthly rising degree; No.1; 1.15$^{\circ}C$, No.2; 1.7$^{\circ}C$, No.3; 1.73$^{\circ}C$, No.4; 2.08$^{\circ}C$, No.5; 2.0$^{\circ}C$), and expressed gradually descended influence upon water temperature after August. 3. The mean temperature of inflow folwed in warm Water pool was 7.5∼12.5$^{\circ}C$, and outflow temperature was described as 13.4∼22.5$^{\circ}C$ to be climbed. And So, the rising interval of water temperature was shown as 6.7∼10.4$^{\circ}C$. 4. The correlation between the rising of water temperature and the weather condition was found out highly significant. As the result, their correlation coefficents of water temperature depending on mean air temperature, ground temperature, wind velocity and relative humidity were to be 0.93, 0.90, - 0.83 and 0.71 respectively. But there was no confrimation of the correlation on the clouds, sunlight time, volume of evaporation, and heat capacity of horizontal place. 5. The water temperature of balance during the period of rice growing in Chuncheon district was shown as table 10, and the mean of whole period was calculated as about 23.7$^{\circ}C$. 6. The observed value of the outflow temperature passed through the warm water pool was higher than that of computed, the mean difference between two value was marked as 1.15$^{\circ}C$ for blockl, 1.18$^{\circ}C$ for block2, and 0.47$^{\circ}C$ for block3, respectivly. Therefore, the ratio on the rising degree between the observed and computed were shown as 53%, 44%, and 18%, mean 38% through each block warm water pool (referring item $\circled9$ of table 11,12, and 13). Accordingly, formula (4) in order to fit for each block warm water pool was transfromed as follow; {{{{ { theta }_{w } - { theta }_{ 0} =[1-exp LEFT { { 1-(1+2 varphi )} over {cp } CDOT { A} over { q} RIGHT } ] TIMES ( { theta }_{w } - { theta }_{ 0}) TIMES C }}}} Here, correction coefficinent was computed 1.38, and being substituted 1.38 for C in preceding formula, the expected water temperature will be calculated to be able to irrigate the rice paddy. As the result, we can apply the coefficient in order to plan and to construct a new warm water pool.

• Coupled systems mechanics
• /
• v.1 no.4
• /
• pp.311-324
• /
• 2012

Previous investigations have demonstrated that strong earthquakes can cause severe damage or collapse to storage tanks. Theoretical studies by other researchers have shown that allowing the tank to uplift generally reduces the base shear and the base moment. This paper provides the necessary experimental confirmation of some of the numerical finding by other researchers. This paper reports on a series of experiments of a model tank containing water using a shake table. A comparison of the seismic behaviour of a fixed base system (tank with anchorage) and a system free to uplift (tank without anchorage) is considered. The six ground motions are scaled to the design spectrum provided by New Zealand Standard 1170.5 (2004) and a range of aspect ratios (height/radius) is considered. Measurements were made of the impulsive acceleration, the horizontal displacement of the top of the tank and uplift of the base plate. A preliminary comparison between the experimental results and the recommendations provided by the liquid storage tank design recommendations of the New Zealand Society for Earthquake Engineering is included. The measurement of anchorage forces required to avoid uplift under varying conditions will be discussed.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.1506-1512
• /
• 2010

In this study, model tests were performed to investigate the settlement characteristics of the rock/soil mixture subgrade with the many portion of mudstone due to the cyclic train loading in high-speed railway. Specially, from the tests varying initial degree of saturation, effects of increment of the degree of saturation in the subgrade due to rainfall or elevation of ground water table under cyclic train loading on the deformation characteristics were analyzed. From the results, in the low degree of saturation, settlement converged to some value. However, in the condition of degree of saturation larger than some value, settlement rapidly increased. Therefore, it was found that it is important to maintain the degree of saturation of subgrade below the specific level to prevent the settlement of subgrade.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.11 no.3
• /
• pp.1731-1738
• /
• 1969

1. For the purpose of analyzing the plan of new reclamation project and its evaluation, actual studies for the existing polders are required. 2. The variations of the salt content of soil, yields and staus of its plantation have been studied for six areas reclaimed in relatively recent years, including Kangwha, Daechon, Chopo, Eushin, Kwangyang and Chinkyo. 3. The annual yields from the project were only 52 percent in the first year as compared with kilograms per 10 a. in the Hachirogata polder in Japan. 4. Such a low productivity in the existing polders in Korea is chiefly by the high ground water table, unfavourable conditions of subdrainage in the root zone, and saline damages of existing high salt content. That is because the depth of drainage ditches is too shallow and layout distance between every drainage ditches is also too long. 5. In order to overcom such a uncertiainties, the drainagedistance suitable for these areas has been Calculated by using the Donnans formula. Applying to the formula, drainage facilities are so densie that land use capability may be decreased. 6. For the purpose of ensuring the effective desalinization and high land use capability, feasible interval to establish the culvert has been studied in accordance with both formulas of Donnan and Hoogan. 7. In order to accomplish the early desalinization in both areas of new reclamation or existing polders, the problems of internal drainages should be resolved. for this puprose in addition to the endeavour of the personnels actually engaged in such works. The actual support of the related agencies for financial assitance is required.

• Journal of Life Science
• /
• v.10 no.2
• /
• pp.169-176
• /
• 2000

At Koppl area, undamaged natural habitat of sundew, I have analysed interspecific affinities and community composition through mathematical method and important environmental factors. Interspecific affinities of the species with frequency of more than 5% in vegetation table were analysed through chi-square test and showed obvious group of Drosera rotundifolia, Vaccinium uliginosum, Calluna vulgaris, Eriophorum angustifolium and 21 species. The result of ordination anlysis using DECORANA of VESPAN II showed eigenvalue of 0.6047 for axis I, 0.2024 for axis II and 0.0763 for axis Ⅲ. And it divided into 4 groups of quadrat number 1-5 for Sphagnum squarrosum-community, 6-10 for Crepis paludosa-community. 11-25 for Carex panicea-community and 26-35 for Scorpidium scorpioides-community. By the classification using TWINSPAN, the 7 areas divided into 2 groups of 1-10 and 11-35 at first level of division with high eigenvalue of 0.588 and indicator was Sphagnum squarrosum. At second level of division it divided into 4 groups as the results of DECORANA with eigenvalues of 0.268 and 0.423 and indicators were Pinguicula vulgaris and Scorpidium scorpioides. Microclimatic environment of studied area was low in temperature and high in humidity and soil environment showed high in field moisture capacity, acid, high organic matter content, low NO3 and K2O content, compare to normal soil, and high ground water level.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.1268-1277
• /
• 2008

Recently, the high speed railway comes into the spotlight as the important and convenient traffic infrastructure. In Korea, Kyung-Bu high speed train service began in about 400km section at 2004, and the Ho-Nam high speed railway will be constructed by 2017. The high speed train will run with a design maximum speed of 300-350km/hr. Since the trains are operated at high speed, the differential settlement of subgrade under the rail is able to cause a fatal disaster. Therefore, the differential settlement of the embankment must be controlled with the greatest care. Furthermore, the characteristics and causes of settlements which occurred under construction and post-construction should be investigated. A considerable number of studies have been conducted on the settlement of the natural ground over the past several decades. But little attention has been given to the compression settlement of the embankment. The long-term settlement of compacted fills embankments is greatly influenced by the post-construction wetting. This is called 'hydro collapse' or 'wetting collapse'. This wetting collapse problem for the compressibility of compacted sands, gravels and rockfills, has been recognized by several researchers. For this wetting settlement problem, we showed the test results carried out with 4 fill materials. These tests were performed under the condition that the fill materials were inundated at the first wetting. Subsequently, in this study, we investigated the long-term settlement characteristics of the fill materials under the repeated partial wetting and rising of the ground water table happend by rainfall.

• Journal of Soil and Groundwater Environment
• /
• v.12 no.5
• /
• pp.19-32
• /
• 2007

In Korea, there have been various methods of estimating groundwater recharge which generally can be subdivided into three types: baseflow separation method by means of groundwater recession curve, water budget analysis based on lumped conceptual model in watershed, and water table fluctuation method (WTF) by using the data from groundwater monitoring wells. However, groundwater recharge rate shows the spatial-temporal variability due to climatic condition, land use and hydrogeological heterogeneity, so these methods have various limits to deal with these characteristics. To overcome these limitations, we present a new method of estimating recharge based on water balance components from the SWAT-MODFLOW which is an integrated surface-ground water model. Groundwater levels in the interest area close to the stream have dynamics similar to stream flow, whereas levels further upslope respond to precipitation with a delay. As these behaviours are related to the physical process of recharge, it is needed to account for the time delay in aquifer recharge once the water exits the soil profile to represent these features. In SWAT, a single linear reservoir storage module with an exponential decay weighting function is used to compute the recharge from soil to aquifer on a given day. However, this module has some limitations expressing recharge variation when the delay time is too long and transient recharge trend does not match to the groundwater table time series, the multi-reservoir storage routing module which represents more realistic time delay through vadose zone is newly suggested in this study. In this module, the parameter related to the delay time should be optimized by checking the correlation between simulated recharge and observed groundwater levels. The final step of this procedure is to compare simulated groundwater table with observed one as well as to compare simulated watershed runoff with observed one. This method is applied to Mihocheon watershed in Korea for the purpose of testing the procedure of proper estimation of spatio-temporal groundwater recharge distribution. As the newly suggested method of estimating recharge has the advantages of effectiveness of watershed model as well as the accuracy of WTF method, the estimated daily recharge rate would be an advanced quantity reflecting the heterogeneity of hydrogeology, climatic condition, land use as well as physical behaviour of water in soil layers and aquifers.

• Tunnel and Underground Space
• /
• v.19 no.6
• /
• pp.534-544
• /
• 2009

The collapse of the underground cavity can cause the abrupt local subsidence of the ground surface. It can be hazardous to the stability of road and building for human activity. Therefore it is necessary to develop reinforcement methods for the filling of the underground cavity. This study was executed to improve the material quality and systems to fill the calcium-aluminate mineral $(C_{12}A_7)$ environmentally, and minimize the loss of filling materials for the steep underground cavity. Filling material which was developed in this study is composed of rapid hardening material and additives. The developed material had rapid hardening and non-separation ability in the water cavity condition, so it made the effective underground dam in the cavity with prevention of material loss when it was poured in the water cavity. Results of heavy metal leaching test for environmental assessment showed that it was environmentally suiTable material for the filling in the mine cavity.