YoungSeok Kim

The Variation of Physical Properties in Frozen Soils at Various Freezing Temperatures

Due to the recent climate change, the colder and longer winter is expected in Korea. Besides, the recent participation agreement on the development of the natural gas pipeline in Russia and construction of the second Korean Antarctic research station, the Jangbogo station changes the research interests from the seasonally frozen ground to the permafrost ground. The recent development of the site investigation techniques using wave propagation and electrical resistivity enabled engineers to evaluate the physical properties of the frozen soils and further correlate them to the mechanical properties. However, the physical properties of the frozen ground change when the water in the soil solidifies to ice; this change is particularly notable between 0 and −10°C. Therefore, the physical property changes due to freezing needs to be investigated in terms of wave propagation characteristics and electrical resistivity with regard to the various freezing temperatures. In this study, the characteristics of wave propagation and electrical resistivity of frozen soils are investigated under various sub-zero temperatures. The characteristics of wave propagations are analyzed in terms of compression and shear wave velocities. The electrical resistivity is measured under various sub-zero temperatures to understand the effects of ice, which will further provide the valuable information about the location of the active layer. Furthermore, the evaluated physical properties can be used as basic data for the evaluation of the mechanical properties such as strength and stiffness.Copyright

A Study on Characteristics of Frost Heaving With Soil Samples From Terra Nova in the East Antarctic Region

The second scientific Antarctica station of South Korea is under construction at Terra Nova Bay located in east Antarctica. The objective of this study is the evaluation of the frost heave susceptibility of soils sampled from the second station site by performing laboratory frost heaving tests. Experiments are carried out with the soil specimens taken from five different areas at Terra Nova Bay. Test specimens are frozen with constant temperatures at the top and bottom of the specimen at −17 °C and 4 °C, respectively. In addition, grain size analyses and unfrozen water tests are also performed for monitoring the characteristics of the water contained in the permafrost. Frost susceptibility is evaluated by standard methods recommended in UK, US and Japan. Experimental results show that the more the fine contents exist in soils, the more frost heave occurs. The result denotes that grain size has a significant effect on frost heave. The results suggest that the frost heaving susceptibility of the frozen ground at the Antarctic site would be effectively evaluated through the grain size and the frost heaving parameters.© 2012 ASME

Characteristics of Waste Lime and Soil Mixture for Reusing of Roadbed Embanking Material

Abstract Currently about 3.2 millon tons of waste lime are accumulated and annually 100,000 tons are producted. This study was carried out to investigate the characteristics of soil mixed with waste lime for reusing of roadbed embanking material. Waste lime used in this study is producted as a by-product in the manufacturing process of making Na 2 CO 3 from local chemical factory in Incheon. In this study, the feasible reuse of waste lime mixed with granite weathered soil, clay, crushed rock was investigated through laboratory tests including specific gravity test, sieve analysis, hydrometer analysis, atterberg limit test, compaction test, unconfined compressive test, CBR test, permeability test, shear test, and abrasion test. The mixing rate is granite weathered soil, clay, crushed rock 80 % respectively and waste lime 20 % by weight. From the test results, it is shown that the waste lime and soil mixtures satisfy the criteria as road embanking material specification. Key Words : Waste lime, Soil mixture, Roadbed, Embanking material

Study of Relation between Elastic Wave Velocity and Electrical Resistivity in Saturated Medium

The geophysical methods including elastic wave velocity and electrical resistivity have been widely used to obtain the geotechnicalproperties. The objective of this study suggests the relationship between elastic wave velocity and electrical resistivity because the twoparameters are function of void ratio. The theory of Gassmann and Archie’s equation are applied for deducing the relation betweengeophysical methods and void ratio. The Field Velocity Resistivity Probe (FVRP) is used to obtain the elastic wave velocity and elec-trical resistivity in field which is southern part of Korea Peninsular. The data gathering is performed in the depth of 6.5~20.1m atevery 10 cm for obtaining various data and investigating the subsurface characterization in detail. For verifying the suggested equa-tion, the measured data applied. The deduced compressional wave velocity shows a similar value with the measured compressionalwave velocity. This study suggests that the proposed equation may be widely applied to estimate the reliability of measured valuesbased on the geophysical method.Key words : void ratio, relation equation, electrical resistivity, elastic wave velocity, field test

Bearing Capacity of Pavement Foundation by Waste Lime Material using the Dynamic Cone Pentrometer

Abstract In-situ California Bearing Ratio(CBR) test has been widely used for evaluating the subgrade condition in pavements. However, because the in-situ CBR test is expensive and takes time for operation, it is difficult to figure out the in-situ characteristics of subgrade strength in detail. For faster and economical operation, the Dynamic Cone Penetrometer(DCP) has been often utilized for estimating the subgrade strength in the field. The purpose of this paper is to determine the relationship between CBR value and DCP index of the embankment constructed with mixtures of soil and waste lime. Waste lime used in this study is producted as a by-product in the manufacturing process of making Na 2 CO 3 from local chemical factory in Incheon. In this field measurement, the geotechnical tests such as field water content, field density, field CBR test, and dynamic cone penetration test were conducted.Key Words : Waste lime, Subgrade, California Bearing Ratio(CBR), Dynamic Cone Penetrometer(DCP)