• Journal of the Korean Institute of Gas
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• v.21 no.1
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• pp.27-33
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• 2017

In this study, the stability of trench slope was analysed in summer and winter seasons for the construction of pipelines in permafrost regions. The construction standards of Korea, Russia and UK were compared for obtaining an optimum trench shape for a pipeline of 30 in. diameter. Using the geotechnical properties of soil in Yakutsk (Russia), the stability of trench slope was analysed using Strength Reduction Method (SRM) according to the horizontal slope angle values of $0^{\circ}$, $10^{\circ}$, $20^{\circ}$ and $30^{\circ}$ and vertical slope angle values of $20^{\circ}$, $30^{\circ}$ and $40^{\circ}$. In both seasons, an increase in the slope angle results in a decrease in the factor of safety. The results show that horizontal slope angle of $30^{\circ}$ was not safe in summer season. At the vertical slope angle of $20^{\circ}$, trench side failure was observed, whereas, ground slope failure was observed at the vertical slope angles of $30^{\circ}$ and $40^{\circ}$. Due to the solidification of pore water at temperatures below $0^{\circ}C$, cementation of soil particles take place. Therefore, the trench slope was found to be stable in the winter season at all vertical and horizontal slop angles, except for special load cases and abrupt temperature changes.

• Journal of the Korean Geosynthetics Society
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• v.23 no.2
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• pp.53-62
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• 2024

Recently, development of non-traditional energy such as oil sands has been actively conducted in the cold region such as Canada. Frozen soil has different thermal and mechanical characteristics from general soil due to its high organic contents. This study evaluated the impact of organic matter content on the thermal and mechanical behavior of frozen soil samples collected from Alberta, Canada, and Gangwon Province, South Korea. As the organic content increases, the maximum dry unit weight decreases and the optimum moisture content increases in compaction tests. In uniaxial compression tests under frozen conditions, the strength of the frozen specimens increased as the temperature decreased. The strength of Canada soil sample increased with higher organic matter content at low temperatures. However, the strength of frozen soil was not significantly affected by organic matter content due to the complex behavior and unfrozen water content. Thermal conductivity tests showed higher thermal conductivity in frozen conditions compared to unfrozen conditions, due to the higher thermal conductivity of ice compared to water. These findings provide essential data for geotechnical design and construction in large-scale projects such as oil sands development in cold regions. Further research is needed to explore the impact of organic matter content on different types of frozen soils.

• Journal of the Korean Geosynthetics Society
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• v.12 no.3
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• pp.75-79
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• 2013

The frost depth is one of important factors in the design of structures such as roadways, buried pipeline, and foundations. A frost indicator with methylene blue solution has several advantages with respect to installation cost, maintenance, and simple measurement. However, as a geotechnical engineering aspect, the accuracy of the frost indicator has not been proved yet. This paper presents experimental and field investigations of the accuracy of the frost indicator and contour maps of maximum frost depth. The contour maps of maximum frost depth can be applied to design geo-infrastructure in South Korea.

• Journal of the Korean GEO-environmental Society
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• v.18 no.12
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• pp.37-45
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• 2017

Structural instability and damage are caused by frost heave during the winter when atmospheric temperature maintains below $0^{\circ}C$. Frost heave is the most representative engineering characteristics of frozen ground and there are various frost susceptibility criteria. Frost susceptibility criteria can be roughly divided into three categories. First, frost susceptibility is determined from particle size distribution, which is practically useful and many countries are adopting. In this paper, several particle size distributions (PSDs) are applied to the frost susceptibility criteria but PSD seems to be not enough to determine whether soils are frost susceptible. Second, it is judged from laboratory frost heave testing results. Laboratory frost heave tests were performed with newly developed thermal controlled triaxial cell and the reliability of frost susceptibility criteria is evaluated. New testing apparatus and method are suitable to meet the existing frost susceptibility criteria. Third, it is compositive frost susceptibility criteria envelope including the particle size distribution, soil classification, and frost heave test. The compositive frost susceptibility criteria envelope should be supplemented based on additional data on various soil types.

• Journal of the Korean GEO-environmental Society
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• v.16 no.6
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• pp.31-38
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• 2015

Recently, the participation on the development of the natural gas pipeline in Russia as well as the recent construction of the second Korean Antarctic research station, the Jangbogo station provide the research interests on the behavior of the permafrost ground. To investigate the effect of fines on the mechanical responses of frozen sands, unconfined compression tests were performed on the frozen sands with 0, 5, 10 and 15% of fine contents at -5, -10 and $-15^{\circ}C$. The poorly graded (SP) Joomunjin sand and kaolinite, silt with low plasticity (ML) were used for the preparation of the frozen soil specimens. The mechanical responses of the tested soils were investigated via unconfined compression tests in the temperature controlled laboratory and analyzed in terms of peak unconfined compressive strength and secant modulus at 50% of the peak strength. As the fine contents increase, the unfrozen water contents increase and thus the strength and stiffness of frozen soils decrease. The increment of the stiffness and strength due to the temperature decrease vary with the fine contents.

• Journal of the Korean Geotechnical Society
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• v.27 no.9
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• pp.67-76
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• 2011

Bearing capacity of pile foundations in cold region is dominated by adfreeze bond strength between surrounding soil and pile perimeter. Adfreeze bond strength is considered to be the most important design parameter for foundations in cold region. Many studies in last 50 years have been conducted to analyze characteristics of adfreeze bond strength. However, most studies have been performed under constant temperature and normal stress conditions in order to analyze affecting factors like soil type, pile material, loading speed, etc. In this study, both freezing temperature and normal stress acting on pile surface were considered to be primary factors affecting adfreeze bond strength, while other factors such as soil type, pile material and loading speed were predefined. Direct shear box was used to measure adfreeze bond strength between Joomoonjin sand and aluminium because it is easy to work for various roughness. Test was performed with temperatures of > $0^{\circ}C$, $-1^{\circ}C$, $-2^{\circ}C$, $-5^{\circ}C$, and $-10^{\circ}C$ and vertical confining pressures of 1atm, 2atm, and 3atm. Based on the test results, the effects of temperature and vertical stress on adfreeze bond strength were analyzed. The test results showed that adfreeze bond strength increases with decreased temperature and increased vertical stress. It was also noted that two types of distinct sections exist, owing to the rate of increase of adfreeze bond strength along the change of freezing temperature: 1)rapidly increasing section and 2)gradually decreasing section. In addition, the results showed that a main factor affecting adfreeze bond strength switches from friction angle to adhesion as freezing temperature decreases.

• Journal of the Korean GEO-environmental Society
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• v.17 no.6
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• pp.23-31
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• 2016

Nowadays abnormal coldness happens frequently in Korea and frost heaving causes unexpected ground deformation which results in severe problems for structures such as roadway, railroad and cutoff slope. 'Frost heave' as one of the primary phenomenon is considered to be an important factor together with 'adfreeze bond-strength' and 'creep deformation' for structural design process in permafrost area. Therefore, the fundamental study for frost heave has to be preceded for design of geo-structures in cold region. While various experimental apparatuses have been developed, there still exist a certain level of limitation to evaluate the frost-heave characteristics as design parameters. There are no standard testing method and criteria for analyzing frost heaving in Korea because temperature controlled testing apparatuses including a freezing chamber are expensive. In this paper, a new standard freezing and thawing testing apparatus is introduced, which simulates various freezing and thawing conditions in a soil specimen by using a temperature controlled triaxial cell. Frost heaving tests were performed to assess the new testing apparatus and experimental procedure to evaluate frost heaving for soils is proposed.

• The Journal of Engineering Geology
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• v.33 no.2
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• pp.275-291
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• 2023

Global warming has made the polar regions more accessible, leading to increased demand for the construction of new resource-development plants in oil-rich permafrost regions. The selection of locations of resource-development plants in permafrost regions should consider the surface displacement resulting from thawing and freezing of the active layer of permafrost. However, few studies have considered surface displacement in the selection of optimal locations of resource-development plants in permafrost region. In this study, Analytic Hierarchy Process (AHP) analysis using a range of geospatial information variables was performed to select optimal locations for the construction of oil-sands development plants in the permafrost region of southern Athabasca, Alberta, Canada, including consideration of surface displacement. The surface displacement velocity was estimated by applying the Small BAseline Subset Interferometric Synthetic Aperture Radar technique to time-series Advanced Land Observing Satellite Phased Array L-band Synthetic Aperture Radar images acquired from February 2007 to March 2011. ERA5 reanalysis data were used to generate geospatial data for air temperature, surface temperature, and soil temperature averaged for the period 2000~2010. Geospatial data for roads and railways provided by Statistics Canada and land cover maps distributed by the North American Commission for Environmental Cooperation were also used in the AHP analysis. The suitability of sites analyzed using land cover, surface displacement, and road accessibility as the three most important geospatial factors was validated using the locations of oil-sand plants built since 2010. The sensitivity of surface displacement to the determination of location suitability was found to be very high. We confirm that surface displacement should be considered in the selection of optimal locations for the construction of new resource-development plants in permafrost regions.

• Journal of the Korean GEO-environmental Society
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• v.15 no.1
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• pp.35-41
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• 2014

Many infra suructure such as road, railway, building and utility foundations have been damaged by the repeated freezing and thawing of the soil during winter and spring every year in seasonal frost region. The frost penetration depth is most important factor in the design of structure such as road, railway and building in seasonal frost region. This paper presents the results of calculation of frost penetration depth and frost heaving in concrete track for railway construction. Model concrete track were installed near the railway track in Gangwon, Gyeonggi, Choongbuk province and frost penetration depth were measured using methylene blue frost penetration depth gauge. Model concrete track in Cheolwon, frost heaving of concrete track were also evaluated. The measure of maximum frost penetration depth and frost heaving can be applied to design railway track for cold region in Korea.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.2
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• pp.35-45
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• 2012

Pseudo static analysis using the Mononobe-Okabe method and numerical analysis considering a small strain nonlinearity from the soil were performed to determine the bearing pressure changes of the inverted T-type retaining wall subjected to earthquake motions. In many cases, an inverted 'T' type retaining wall of more than 10 m shows bearing capacity failure under earthquake conditions, despite showing sufficient bearing capacity during normal conditions. The most important reason for this is the change of the effective base area during an earthquake. In this paper, the change of the effective base area of an inverted 'T' type wall is analyzed by using finite difference element code (FLAC). In addition, the effect of dynamic bearing capacity coefficients (which has been suggested by several researchers but not adopted in current design codes and procedures) was verified.