• Journal of the Korean Geotechnical Society
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• v.26 no.9
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• pp.25-35
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• 2010

Settlement at reclamation area caused by secondary compression should be considered using spatial evaluating method because the thickness of consolidation layer varies at every location. Probabilistic method can be implemented to evaluate uncertainty of spatial distribution of secondary compression. This study spatially evaluated mean and standard deviation of secondary compression in the overall analyzing region using spatial distribution of consolidation thickness estimated by ordinary kriging method and statistical values of soil properties. And then, the area where secondary compression exceeds a design criterion at the specific time was evaluated using probabilistic method. It was observed that the area exceeding the design criterion increased as the variability of $C_{\alpha}/(1+e_o)$ increased or the probabilistic design criterion 0: decreased. It is considered that the probabilistic method can be used for the geotechnical design of soft ground when a probabilistic design criterion is established in the specification.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6C
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• pp.349-358
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• 2008

In performing the reliability analysis for predicting the settlement with time of alluvial clay layer at Kobe airport, the uncertainties of geotechnical properties were examined based on the stochastic and probabilistic theory. By using Terzaghi's consolidation theory as the objective function, the failure probability was normalized based on AFOSM method. As the result of reliability analysis, the occurrence probabilities for the cases of the target settlement of ${\pm}10%,\;{\pm}25%$ of the total settlement from the deterministic analysis were 30~50%, 60%~90%, respectively. Considering that the variation coefficients of input variable are almost similar as those of past researches, the acceptable error range of the total settlement would be expected in the range of 10% of the predicted total settlement. As the result of sensitivity analysis, the factors which affect significantly on the settlement analysis were the uncertainties of the compression coefficient Cc, the pre-consolidation stress Pc, and the prediction model employed. Accordingly, it is very important for the reliable prediction with high reliability to obtain reliable soil properties such as Cc and Pc by performing laboratory tests in which the in-situ stress and strain conditions are properly simulated.

• Asian Journal of Turfgrass Science
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• v.23 no.1
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• pp.143-150
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• 2009

High salt concentration is one of the most important limit factor on plant growth at a disused saltpan for golf course construction site. The control of salt in soil is definitely required and the monitoring of salt concentration in soil and ground water also required to amend soil physiochemical properties. This research was carried out to monitor the pH and salt concentration changes by the height of ground water. By the physiochemical analysis test, the soil contains a high salt concentration and classified as a slight alkaline clay soil. The height of ground water table changed to 1.3m, 3.3m and 2.8m at dry season(mid-late June, 2005), monsoon season(early-mid July) and after monsoon(late July), respectively. Compare to the average ground level of 2.9m, the ground water was over flooded about OAm at monsoon season. The electrical conductivity(ECe) was measured above $4.0dS{\cdot}m^{-1}$ over all areas and however, some areas showed over $20dS{\cdot}m^{-1}$. During a monsoon season, ECe was lowered to $1.2{\sim}15.0dS{\cdot}m^{-1}$, compared with those of the dry season. Therefore, the interception of the capillary connection between planting layer and ground water which contains high salt concentration should be adapted when golf courses are constructed on disused saltpan. The phytotoxicity caused by salt damage may be controled by the interception of capillary fringe of salt flow to the topsoil profile at the upper layer of the ground water table.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.2
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• pp.132-138
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• 2009

Soils originated from limestone, located at the southern part of Kangwon province and Jecheon, Danyang of Chungbuk province are mainly composed of fine texture, have different properties from soils originated from granite and granite gneiss, especially for water movement. This study was conducted for making PTF(Pedo-Transfer Function) for Kfs(field saturaton hydraulic conductivity) estimation, and for investigating the relation between soil particle distribution and the infiltration and percolation rate in soils originated from limestone. Soils used for the experiment were 6 soils of Gwarim, Mosan, Jangseong, Maji, Anmi and Pyongan series. Infiltration and percolation rate for the soil were measured by a disc tension infiltrometer and a Guelph permeameter, respectively. The particle size distribution and organic matter content of the soils were analyzed. Kfs was not related with sand, silt, clay, and organic mattrer (OM) content because of forest soils which contained high gravel, pebble, and cobble content, and O layer with high OM content. After Mosan soil series and O layer of Gwarim series were excluded for the data analysis, Kfs was explained as a linear function with sand and clay content and a exponential function with OM content. As a result, the PTF equation was obtained as Kfs=-4.20558+0.479706*(S)+0.023187*exp(1.829*OM) ($R^2=0.6558^{*}$).

• The Journal of the Acoustical Society of Korea
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• v.32 no.1
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• pp.14-21
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• 2013

The erosion, suspension, and transport of sediment frequently occur in the coastal waters and estuarine. These processes often generate the so-called fluid mud layer, which is defined as a high-concentration aqueous suspension of fine grained sediment (> 10 g/l), consisting mainly of silt and clay-size particles. Therefore the high-resolution ultrasound is mostly used to detect or monitor the fluid mud layer. Because the sound attenuation tends to increase rapidly with the suspended sediment concentration, it is necessary to consider the accurate attenuation correction to estimate the backscattering strengths from the suspended sediment layers. In this paper, the volume backscattering strengths with various suspended sediment concentrations were measured using 5-MHz ultrasound signal in a small-scale water tank. The sound attenuation due to the viscosity and scattering from suspended sediment particles was predicted by the Richard's model and applied to the sonar equation to estimate the volume backscattering strengths from the suspended sediment concentrations. For the case that the additional attenuation was not considered, the volume backscattering strengths increased to the concentration of 20 g/l, and over this point, the backscattering strengths were roughly constant. However, for the case that the attenuation due to the suspended sediment concentration was considered, the backscattering strengths increased with the concentration.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.2
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• pp.72-77
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• 1994

This study was conducted to investigate the influence of treatment of fly ash on heavy metal contents of the arable soil. Rice was cultivated on the two types of paddy field clay loam and sandy loam with 0, 12ton/10a of anthracite fly ash and bituminous coal fly ash application. And soybean was cultivated at the same type of upland fields with those ashes of 0, 9ton/10a, yearly for three years. At the harvest time, the heavy metal contents in the different layer were investigated. The results were summarized as follows : 1. The contents of some heavy metal were increased in the surface soils but didn't show the tendency in the deeper layer or soil texture. 2. In the paddy fields, the contents of Cd, Cu, Zn, Cr were increased. Meanwhile and the upland fields, the contents of Cd and Cr were increased with the successive application of Anthracite fly ash, but the others didn't show those tendency. 3. The contents of Cd, Cu and Zn in the paddy field, were increased but the upland field, the contents of Cd, Cr and Ni were increased by the successive application of bituminous coal fly ash.

• Journal of the Korean Geosynthetics Society
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• v.4 no.2
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• pp.11-18
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• 2005

A pilot scale filed model test and 2-D numerical analysis was conducted to evaluate the effectiveness of constructing a geogrid-reinforced and pile-supported embankment system over soft ground to reduce differential settlement, and the results are presented hearin. Three-by-three pile groups with varying the space between pile were driven into a layer of soft marine clay and a layer of geogrid was used as reinforcement over each pile group. 2-D numerical analysis has been conducted by using the FLAC-2D(Fast Lagrangian Analysis of Continua) program for same condition of field model test. The settlement, vertical stress, and strain of geogrid due to the construction of embankment were measured at various locations. Based on the field model test and numerical analysis results, pile reinforcement generated the soil arching at the midspan of pile cap and the geogrid reinforcement helps reduce the differential settlement of the soft ground by tensile strength of geogrid. Also for $D/b{\geq}6.0$, the effectiveness of geogrid reinforcement in reducing settlement is negligible.

• Journal of the Mineralogical Society of Korea
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• v.15 no.3
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• pp.221-230
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• 2002

Weathering of biotite shows a biotite-vermiculite-kaolinite sequence at the early stage, but presents biotite-kaolinite sequence without a significant intermediate phase (vermiculite) at the late stage from the weathering profile of the granitic gneiss. Secondary 1:1 phyllosilicates are kaolinite and halloysite which show different weathering textures originated by a different formation mechanism. Kaolinitization began from the edges of biotite and propagated toward the interior of grain along a multilayered front. $10 \AA$ layers of biotite are interleaving with $7\AA$ layers of kaolinite and c-axis of two phases is consistent. Kaolinite pseudomorph of biotite is isovolumetric, compared to the biotite boundary and includes many band-like porosities parallel to the cleavage. Platy kaolinite formed by 1:1 layer fur layer replacement of biotite. Halloysitization proceeded outward from the grain edges which were foliated as fine flakes and bent at the right angle for cleavage Halloysites were extensively fanning out and greatly increased the volume of grain. This indicated that halloysite tubes were formed by epitaxial overgrowth on the surface of biotite with import of Si and Al from the external solution by dissolution of plagioclase. These halloysites have abnormally high Fe content ( ~11%).

• Economic and Environmental Geology
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• v.33 no.2
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• pp.91-100
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• 2000

It has been more than ten years since Dukun mine was abandoned. Tailings of waste deposits and slime dumps in the abandoned Dukum mine have been left to be deserted for fifty years. The results of fifty years of neglecting are nothing short of major environmental problems. Slime dumps have been exposed to air and water in the mine over ten years and then soil profile has been formed well. Soil in the upper layer (A horizon) is the light gray color due to the leaching of cations. Soil in the lower layer (A2 horizon, 0.2∼0.3m)is tinted with reddish brown and yellowish brown color due to the development of iron oxides and iron hydroxides. Soil in the lower part of B horizon of (1.0∼3.0m) with the growth of copper and zinc oxides exposes to the bluish green, light blue, and dark gray. Ranging from 3m to 8m in depth, 85 samples were taken from 22 sampling sites with 50m intervals located on the slime dump area with hand auger and trench (open cut). As tailings was distributed, heavy metal elements extracted by the process of surface water and ground water move and disperse in to the hydrosphere. Waste dumps were distributed in and around the mine and water draining from those dumps be a potential source of contamination. Soils, thus, can be dispersed into downslope and downstream through wind and water by clastic movement. These materials may be deposited in another horizon if the water is withdrawn, or if the materials are precipitated as a result of differences in pH, or other conditions in deeper horizons. These were primarily associated with acid mine drainage. The characteristics and rate of release of acid mine drainage are influenced by various chemical and biological reactions at the source of acid generations. Prolonged extration of heavy metal elements has a detrimental effect on the agricultural land and residental area. Twenty soil samples were collected from the agricultural land in the area (0∼30 cm). Seventeen samples were also taken from the sediment in the stream running alongside the dumps. The dispersion patterns of heavy metal elements are as follows: The content of As ranged 2∼6 ppm in a horizon, 20∼125 ppm in B horizon with large amount of clay mineral is concentrated and the content of Cd ranged 1∼2 ppm in A horizon, 4∼22 ppm in B horizon. Like Cd, the content of As, Cu, Zn, Pb in B horizon is higher than that in A horizon (approximately 5∼100 times). When soil formation proceeds in stages, it is necessary to investicate the B horizon with the concentration of heavy metal and preventive measures will have to established.

• Asian Journal of Turfgrass Science
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• v.26 no.2
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• pp.129-134
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• 2012

Research was focused on the improvement of poor drainage problems on golf course fairway which had not been performed soil test or properly amended during the course construction. The analysis of the drainage problem basically was caused by a deterioration of soil physical properties by the top layer compaction. The soil hardness reached about 3,000 Kpa around 5~6 cm of soil profile. The slow infiltration speed to subsoil by the compaction was caused directly a poor drainage capacity. However, the properly amended sand soil showed an apparent value of 1,500 Kpa through the subsoil. The water content test showed a similar result that higher rate of 20~30% and ideal rate of 8~12% at poor drainage area and successfully amended area, respectively. However, an imported topsoil media which had higher content of silt and clay from a trans-planted sod had made a heterogeneous soil profile and that caused a poor drain capacity by a low infiltration rate. Those drainage problems triggered to buildup a reduced soil layer by poor soil gas exchange. The soil environment of deoxidation enhanced anaerobic microbial population and induced methane gas build-up to 55 ppm, and that resulted an adverse effect on turf growth by root growth retardation, consequently.