• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.105-112
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• 2006

Liquefaction-induced lateral spreading has been the most extensive damage to pile foundations during earthquakes. However, a case of pile failure was reported despite the fact that a large margin of safety factor was employed in their design. This means that the current seismic design method of pile is not agreeable with the actual failure mechanism of pile. Newly proposed failure mechanism of pile is a pile failure based on buckling instability. In this study, failure behavior of pile embedded in liquefied soil deposits was analyzed considering lateral spreading and buckling instability performing 1g shaking table test. As a result, it can be concluded that the pile subjected to excessive axial loads ($near\;P_{cr}$) can fail by buckling instability during liquefaction. When lateral spreading took place in sloping grounds, lateral spreading increased lateral deflection of pile and reduced the buckling load, promoting more rapid collapse. In addition, buckling shape of pile was observed. In the ease of pile buckling, hinge formed at the middle of the pile, not at the bottom. And in sloping grounds, location of hinge got loiter compared with level ground because of the effects of lateral spreading.

• Geomechanics and Engineering
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• v.19 no.6
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• pp.543-554
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• 2019

İzmir Bay reserves high amount of residual alluvial deposits generated by Meles River at its stream mouth. These carried sediments with high water content and low bearing capacity are unsuitable in terms of engineering purposes. In-situ soil stabilization with deep soil mixing method is considered to improve properties of soil in this location. This method is widely used especially over Scandinavia, Japan and North America. Basically, the method covers mixing appropriate binder into the soil to improve soil profile according to the engineering needs. For this purpose, soil samples were initially provided from the site, classification tests were performed and optimum ratios of lime and cement binders were determined. Following, specimens representing the in-situ soil conditions were prepared and cured to be able to determine their engineering properties. Unconfined compression tests and vane shear tests were applied to evaluate the stabilization performance of binders on samples with different curing periods. Scanning electron microscope was used to observe time-dependent bonding progress of binders in order to validate the results. Utilization of 4% lime and 4% cement mixture for the long-term performance and 8% lime and 8% cement mixture for short term performance were suggested for the stabilization of Meles Delta soils. Development of CSH and CAH in a gel form as well as CSH crystals were clearly observed on SEM images of treated specimens.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.859-865
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• 2011

This study looked into 110 sites of orchard fields to investigate the relationships between the physical and chemical properties of soils, including heavy metal contents, and the topographic characteristics of the fields in Jeonbuk province. The topographic distribution of orchard fields in Jeonbuk province was local valley and fans, hilly and mountains, mountain foot slopes, alluvial plains, diluvium, and fluvio-marine deposits. Forty-six percent (46%) of total orchard fields were located in the hilly and mountains. Soil texture of the local valley and fans was mostly sandy clay loam, and the soil texture of other topographical sites were varied. Bulk density, porosity, and soil hardness were not different among the various topographic sites. The content of plant available water was the highest (19.5%) in the sites of diluvium. Soil pH, electrical conductivity (EC), and exchangeable $Mg^{2+}$ content were the highest in the sites of fluvio-marine deposits, whereas the contents of soil organic matter (SOM), available phosphorus, and exchangeable $Ca^{2+}$, $K^+$, and $Na^+$ were not significantly different among the topographic sites. Also, soil pH and SOM content were generally in optimal ranges for the fruit plants in the orchard fields, but other values were mostly higher than those in optimum. In addition, the contents of heavy metals were much lower than the levels of Soil Contamination Warning Standard.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.940-950
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• 2010

In case of uneven surcharge like backfill or embankment after constructing caisson applied on the deep soft marine deposits, lateral deformation of soft soils would happen due to plastic deformation of soil particles by increase of excess pore water pressure. Lateral deformation of soil will result in the caisson displacement which affects soft soil-caisson structure safety. Soft soil was improved by soil compaction pile method, and then gravity caisson was installed. Soil deformations were monitored and analyzed with step by step backfill and embankment behind the caisson. Amount and speed of lateral deformation after the installation of caissons were closely related with the time of backfill and embankment. The relationship between maximum lateral displacement($\Delta_y$) in front of caisson and settlement($\Delta_s$) can be expressed as $\Delta_y=(0.0871)\Delta_s+122.95$. Soft soil depth did not affect the lateral displacement of caisson in this study, which can be explained the soft soil improvement under the caisson by S.C.P. method. Substantially the amount and speed of the lateral deformation of caisson were closely related with the uneven surcharging rate behind caisson.

• Economic and Environmental Geology
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• v.25 no.2
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• pp.145-151
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• 1992

In order to study the optimum depth for the soil geochemical exploration in the area which is affected by agricultural activities and waste disposal of metal mine, the soil samples were sampled from the B layer of residual soil and vertical 7 layers up to 250 cm in the rice field and 3 layers up to 90 cm in the ordinary field. They were analyzed for Au, As, Cu, Pb and Zn by AAS, AAS-graphite furnace and ICP. To investigate the proper depth for the soil sampling in the contaminated area, the data were treated statistically by applying correlation coefficient, factor analysis and trend analysis. It is conclude that soil geochemical exploration method could be applied in the farm-land and a little contaminated area. The optimum depth of soil sampling is 60 cm in the ordinary field, and 150~200 cm in the rice field. Soil sampling in the area of a huge mine waste disposal is not recommendable. Plotting of geochemical map with factor scores as a input data shows a clear pattern compared with the map of indicater element such as As or Au. The second or third degree trend surface analysis is effective in inferring the continuity of vein in the area where the outcrop is invisible.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.3
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• pp.393-398
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• 2012

We investigated the changes in chemical properties of paddy field soils at 300 different sampling sites containing 4 topography in Jeonbuk province, Korea. The soil samples were collected 43.0% from local valley and fans, 39.3% from fluvio-marine deposits, 15.0% from alluvial plains, and 2.7% from diluvium sites. The optimal values of soil properties in the total soil samples were as follows: 65.3% of total samples in soil pH value, 48.3% of total samples in cation exchange capacity (CEC) value, and 22.3% of total samples in available phosphorus content, whereas the deficient values of soil properties were 63.3% of total samples in soil organic matter (SOM) content, 75.7% of total samples in available silicate content, and 61.3%, 51.0%, and 59.3% of total samples in exchangeable $K^+$, $Ca^{2+}$, and $Mg^{2+}$ concentrations, respectively. There were different soil types in the paddy fields: that is, 34.4% immature paddy and 33.6% sandy paddy in the local valley and fans, 57.8% sandy paddy in the alluvial plains, 47.4% normal paddy in the fluvio-marine deposits, and 75.7% immature paddy in the diluvium. Soil textures were also different: 53.5% loam in the local valley and fans, 37.8% sandy loam in the alluvial plains, and 55.1% silty loam in the fluvio-marine deposits. Soil pH and SOM contents were not different among the different topographical sampling sites. However, the mean value of available phosphorus content, 224 mg $kg^{-1}$, was exceeded optimal values in the diluvium. The contents of exchangeable cations were optimal in all the sites, except exchangeable $Ca^{2+}$ contents in the local valley and fans. The contents of available silicate ranged between 112 and 127 mg $kg^{-1}$ in all the sites, which were lower than optimal value. In addition, soil pH values were proportionally correlated to the order of available silicate, exchangeable $Ca^{2+}$, $Mg^{2+}$, $Na^+$, CEC, and exchangeable $K^+$. The contents of SOM were proportionally correlated to the order of CEC, available $P_2O_5$, exchangeable $Ca^{2+}$, and available silicate. The contents of heavy metals, Cd, Cr, Cu, Ni, Pb, and Zn, were only 10% of the threshold levels of the metals, and As content was about 20 to 30% of the threshold level.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.2
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• pp.89-97
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• 1986

To clarify the soil characteristics and genesis of the clayey terrace soils in Yeongnam area, the study were carried out with 9 typifying pedons of toposequential terrace soils in Yeongcheon (inland area) and Yeongil (coastal area) region. The results of soil genesis oriented investigations on soil mineralogical compositions and weathering characteristics were summarized as follows; 1. The contents of heavy minerals contained in sand fraction of the terrace soils were less than 5%, but the content in soil layers considered to be originated from other than terrace deposits had 9.8-16.2%. The content of feldspars in light minerals were higher in Yeongcheon sequence while the Yeongil sequence were characterized by having higher content in quartz. The ratios of quartz/feldspars in the soil layers where expecting lithological discontinuity, were different from that of terrace deposits. 2. The resistate index of maturity ranged around 76.7-29.9 in Yeongcheon area and around 85.6-67.2 in Yeongil area. The indices increased with the elevations of terraces. 3. The molar ratios of $SiO_2/Al_2O_3$ in clay fraction were around 1.93-2.65. The parent materials of the terrace deposits judged by the ratios of $Al_2O_3/TiO_2$ and $Fe_2O_3/Al_2O_3$ were considered to be the felsic materials. 4. The compositions of clay minerals detected by X-ray diffractogram and D.T.A. thermogram were dominated by kaolin and illite with subsidiary minerals of vermiculite, quartz, vermiculite intergrading to illite etc. It was distinguished from terrace deposits that by having higher amount of kaolin and montmorin minerals in the substrata of Bancheon soils in Yeongcheon area and Upyeong soils in Yeongil area, respectively.

• The Korean Journal of Quaternary Research
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• v.21 no.2
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• pp.77-79
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• 2007

The source regions of Asian Dusts (Yellow Sands) in the western part of China are investigated, and the soil samples are collected samples for approximately 15 days during the spring of 2005. Particle sizes of sediments are analyzed and compared with each other. These grain-size analyses from the source areas can be compared Particle sizes between loess deposits and desert sands in western part of China and desert areas show distinctive differences. Loess deposits are predominantly composed of fine sands and silts. The distinction between the final characteristics of Asian Dust particles arrived in Korea and characteristics during transportation can be recognized comparison with the Asian Dust particles collected where the dust particles settled down. The characteristics of Asian Dust particle sizes can provide the basic information regarding the transportation history from the source region.

• Proceedings of the Korean Geotechical Society Conference
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• 1992.10a
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• pp.145-148
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• 1992

This paper reports the application of field tests to weak ground. In this study, field and laboratory tests were performed in the west seashore of KOREA(Ildo, Sore, Kunsan, Youngam). Applied tests are standard penetration test, cone penetration test, dilatometer test, field vane test, unconsolidated undrained test, oedometer test and other fundametal material properties tests. The results of in-situ test are used to estimate soil types and undrained shear strengths of five clay local deposits. SPT results showed low reliability and FVT war also demonstrated the best field test to weak clayey deposits.

• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.110-115
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• 1998

Through the ISODATA method, the micro-landform of Julpo-Bay tidal flat was classified into mudflat, mixedflat, and sandflat using Landsat TM image. Each showed an apparent differences in its topographical characteristics and grain size composition. For example, mudflats are formed with flat faces and tidal channel of dissected gully. Its characteristics of grain size analysis that the grains have less than mean grain size 4 phi. Its sorting is bad (higher than 1 S.D.), and it showed strongly positive skewness. But sandflat is topographically flat without tidal channel. It has developed with ripple marks. According to the grain size analysis of deposits, the soil is coarse size with 90% of sand and its sorting is well(lower than 1 S.D.) Also, it showed strongly negative skewness. Mixed flat is in between mudflat and sandflat in its characteristics.