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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Geotechnical Society
Journal Basic Information
Journal DOI :
Korean Geotechical Society
Editor in Chief :
Seong Wan Park
Volume & Issues
Volume 29, Issue 12 - Dec 2013
Volume 29, Issue 11 - Nov 2013
Volume 29, Issue 10 - Oct 2013
Volume 29, Issue 9 - Sep 2013
Volume 29, Issue 8 - Aug 2013
Volume 29, Issue 7 - Jul 2013
Volume 29, Issue 6 - Jun 2013
Volume 29, Issue 5 - May 2013
Volume 29, Issue 4 - Apr 2013
Volume 29, Issue 3 - Mar 2013
Volume 29, Issue 2 - Feb 2013
Volume 29, Issue 1 - Jan 2013
Selecting the target year
Dynamic Response for Critical Velocity Effect Depending on Supporting Stiffness of High-Speed Railway Trackbed
Lee, Il-Wha ;
Journal of the Korean Geotechnical Society, volume 29, issue 1, 2013, Pages 5~12
DOI : 10.7843/kgs.2013.29.1.5
The critical velocity effect on railway trackbed means the amplification of vibration energy when the train running-speed and group velocity of ground surface wave are superimposed. It is called a pseudo-resonance phenomenon of time domain. In the past, it was not issued because the train speed was low and the ground group velocity was higher. But since the high-speed train is introduced, critical velocity reported causing a track irregularity. So far, theoretical analysis has been performed because of the complexity of formation process. However it requires reasonable consideration which is similar to actual track and trackbed conditions. In the present paper, finite element analysis to verify the critical velocity effect is performed considering each track structure and trackbed supporting stiffness. As a result, the deformation amplification caused by the critical velocity effect is verified to analyze each supporting stiffness and track system.
Numerical Investigation into Behavior of Retaining Wall Subject to Cycles of Wetting and Drying
Yoo, Chung-Sik ;
Journal of the Korean Geotechnical Society, volume 29, issue 1, 2013, Pages 13~22
DOI : 10.7843/kgs.2013.29.1.13
This paper presents the results of a numerical investigation into the behavior of retaining wall subject to cycles of wetting and drying due to rainfall. The stress-pore pressure coupled finite element modeling strategy was first established for stimulating the wall behavior. A series of finite element analyses were then performed on a range of conditions including different rainfall and backfill conditions. The results indicated that the rainfall intensity was the primary influencing factor for the wall behavior. Also revealed was that the pre-rainfall condition determines the magnitudes and the distribution of matric suction which in fact has a significant impact on the behavior of wall during a major rainfall. This result demonstrates the importance of incorporating the pre-rainfall condition for numerical modeling of walls during heavy rainfall. Practical implications of the findings from this study are discussed in great detail.
Debris Flow Mobility: A Comparison of Weathered Soils and Clay-rich Soils
Jeong, Sueng-Won ;
Journal of the Korean Geotechnical Society, volume 29, issue 1, 2013, Pages 23~27
DOI : 10.7843/kgs.2013.29.1.23
The risks of debris flows caused by climate change have increased significantly around the world. Recently, landslide disaster prevention technology is more focused on the failure and post-failure dynamics to mitigate the hazards in flow-prone area. In particular, we should define the soil strength and flow characteristics to estimate the debris flow mobility in the mountainous regions in Korea. To do so, we selected known ancient landslides area: Inje, Pohang and Sangju debris flows. Firstly we measured physical and mechanical properties: liquidity index and undrained shear strength by fall cone penetrometer. From the test results, we found that there is a possible relationship between liquidity index and undrained shear strength,
, in the selected areas, even though they were different in geological compositions. Assuming that the yield stress is equal to the undrained shear strength at the initiation of sliding, we examined the flow characteristics of weathered soils in Korea. When liquidity index is given as 1, 1.5 and 3.0, the debris flow motion of weathered soils is compared with that of mud-rich sediments, which are known as low-activity clays. At
, it seems that debris flow could reach approximately 250m after 5 minutes. As liquidity index increased from 1 to 3, the debris flow propagation of weathered soils is twice than that of low-activity clays. It may be due to the fact that soil masses mixed with the ambient water and then highly fragmented during flow, thereby leading to the high mobility. The results may help to predict the debris flow propagation and to develop disaster prevention technology at similar geological settings, especially for the weathered soils, in Korea.
Correlation between Compressive Strength and Unit Weight of Lightweight Foamed Controlled Low Strength Material (CLSM) Using Coal Ash
Lee, Jong-Hwi ; Lee, Hye-Jin ; Chun, Byung-Sik ;
Journal of the Korean Geotechnical Society, volume 29, issue 1, 2013, Pages 39~47
DOI : 10.7843/kgs.2013.29.1.39
With the increase in the application of CLSM using coal ash, we performed a basic research on CLSM material, laying focus on the correlation between compressive strength and unit weight of lightweight foamed CLSM. The unconfined compression strength is a criterion for the judgment of the possibility of re-excavation and an important factor determining the economy, efficiency, and excavation character. However, to know the quantitative compression strength value takes a certain amount of time, because the applicability of unconfined compression strength of CLSM is judged by the standard of 28days. Therefore, in this study the relation between compressive strength and unit weight (foam slurry unit weight, apparent unit weight) is analyzed focusing on lightweight foamed CLSM. We also suggested a formula which can easily predict the 28-day compressive strength only using unit weight value without the need to cure the slurry for 28 days.
A Study on Rainfall-induced Erosion of Land Surface on Reinforced Slope Using Soil Improvement Material
Kim, You-Seong ; Kim, Jae-Hong ; Bhang, In-Hwang ; Seo, Se-Gwan ;
Journal of the Korean Geotechnical Society, volume 29, issue 1, 2013, Pages 49~59
DOI : 10.7843/kgs.2013.29.1.49
Heavy rainfall intensity may cause shallow slope failures and debris flow by rill erosion and scour on land surface. The paper represents the difference between native soil (weathered soil) and reinforced soil, which is mixed by hardening agent with flyash as main material, for investigating experimental findings of rill erosion and erosion. Results obtained from artificial rainfall simulator show that erosion rate of reinforced soil mixed with hardening agent is reduced by 20% because an amount of eroded soil on slope surface is inversely proportional to the increase of soil strength. For example, rainfall of 45mm (at the elapsed time of 25mins in rainfall intensity of 110mm/hr) triggers rill erosion on native soil surface, but the rill erosion on reinforced soil surface does not even occur at 330mm rainfall (at the elapsed time of 3hrs in rainfall intensity of 110mm/hr). As a result of slope stability analysis, it was found that the construction method for reinforced soil surface would be more economical, easy and fast construction technology than conventional reinforcement method.
A Numerical Investigation on End Bearing Capacity of Single Pile Installed in Fractured Rock Mass
Kim, Tae-Jung ; Yoo, Chung-Sik ;
Journal of the Korean Geotechnical Society, volume 29, issue 1, 2013, Pages 61~70
DOI : 10.7843/kgs.2013.29.1.61
This paper presents the results of a two-dimensional finite element analysis of end bearing capacity of single pile installed in fractured rock mass. A number of cases were analyzed using Hoek-Brown criterion that can consider the condition of rock joints. Considering a wide range of joint conditions in which the pile is embedded into the rock, GSI was set as a main parameter. And the effects of pile diameter, unconfined compressive strength of rock and Hoek-Brown constant
were considered. Based on parameter study, end bearing load factor graphs were suggested.
A Characteristics of the Strength Recovery of the Soil Adjacent to the Pile Depending on the Construction Methods of a Environment-friendly Screw Concrete Pile for a Noise- and Vibration-free Method
Kim, Dong-Chul ; Choi, Youngkyu ;
Journal of the Korean Geotechnical Society, volume 29, issue 1, 2013, Pages 71~80
DOI : 10.7843/kgs.2013.29.1.71
Before and after the test constructions, and after an 11-month hiatus from the pilot pile installations, the in-situ tests (CPT, SPT) were carried out at the ground adjacent to the noise- and vibration-free screw concrete piles installed by 2 kinds of construction methods (i.e., the toe-jetting shoe type, the pre-digging type). In the toe-jetting shoe type construction methods, after construction, the soil strength within 3.5D (where, D = pile diameter) from the pile center decreased greatly by about 46% of the original ground and, after an 11-month hiatus, a strength recovery adjacent to the piles appeared about 71% of the original ground. In the pre-digging type construction methods, a strength recovery adjacent to the piles appeared 100% of the strength of the original ground.
Numerical Investigation into Behavior of Retaining Wall Subject to Cycles of Freezing and Thawing
Yoo, Chung-Sik ;
Journal of the Korean Geotechnical Society, volume 29, issue 1, 2013, Pages 81~92
DOI : 10.7843/kgs.2013.29.1.81
This paper presents the results of a numerical investigation into the behavior of retaining wall subject to cycles of freezing and thawing due to seasonal temperature change. The thermo-hydro-mechanical coupled finite element modeling strategy was first established to simulate the wall behavior. A series of finite element analyses were then performed on a range of conditions representing seasonal temperature change characteristics. The results indicated that the average freezing temperature and the number of cycles of freezing and thawing were the primary influencing factors for the wall behavior. Also revealed was that the duration of freezing period does not significantly affect the wall displacement and the lateral earth pressure, and that the earth pressure on the wall does not significantly change due to the freezing and thawing action suggesting that the increase in the wall displacement during the freezing and thawing action may be attributed to degradation of backfill due to the freezing and thawing action.
Study on Evaluation of Effective Thermal Conductivity of Unsaturated Soil Using Average Capillary Pressure and Network Model
Han, Eunseon ; Lee, Chulho ; Choi, Hyun-Jun ; Choi, Hangseok ;
Journal of the Korean Geotechnical Society, volume 29, issue 1, 2013, Pages 93~107
DOI : 10.7843/kgs.2013.29.1.93
Thermal conduction of the particulate composites or granular materials can be widely used in porous materials and geotechnical engineering. And it has continued to develop "effective thermal conductivity" of medium by modeling energy relationship among particles in medium. This study focuses on the development of the effective thermal conductivity at the unsaturated conditions of soils using the modified network model approach assisted by synthetic 3D random packed systems (DEM method, Discrete Element Method) at the particle scale. To verify the network model, three kinds of glass beads and the Jumunjin sand are used to obtain experimental values at various unsaturated conditions. The PPE (Pressure Plate Extractor) test is then performed to obtain SWCC (Soil-Water Characteristic Curve) of soil samples. In the modified network model, SWCC is used to adjust the equivalent radius of thermal cylinder at contact area between particles. And cutoff range parameter to define the effective zone is also adjusted according to the SWCC at given conditions. From a series of laboratory tests and the proposed network model, the modified network model which adopts a SWCC shows a good agreement in modeling thermal conductivity of granular soils at given conditions. And an empirical correlation between the fraction of the mean radius (
) and thermal conductivity at given saturated condition is provided, which can be used to expect thermal conductivity of the granular soils, to estimate thermal conductivity of granular soils.
Undrained Characteristics of Geogrid-Encased Stone Column under Cyclic Load Using Reduced-Scale Model Tests
Choi, Jin-Wook ; Lee, Dae-Young ; Yoo, Chung-Sik ;
Journal of the Korean Geotechnical Society, volume 29, issue 1, 2013, Pages 109~120
DOI : 10.7843/kgs.2013.29.1.109
This paper presents the results of a laboratory investigation into a study on undrained characteristics of a geogrid-encased stone column (GESC) installed in soft clay under cyclic load. In order to analyze behavior of settlement, pore water pressure, stress concentration ratio and strain of the GESC compared to a stone column, a series of reduced-scale laboratory tests were performed. The model tests show that GESC provides a simple and effective method of deformation resistance and settlement restraint when a short-term cyclic load is applied. The maximum strain of geogrid occurred at 1.2D and 1.5D from the top of the column. This paper highlights the importance of considering overlay effect and replacement ratio on cyclic load supporting GESC.
Pull-out Capacity of Screw Anchor Pile in Sand Using Reduced-Scale Model Tests
Kim, Dae-Hyun ; Yoo, Chung-Sik ;
Journal of the Korean Geotechnical Society, volume 29, issue 1, 2013, Pages 121~133
DOI : 10.7843/kgs.2013.29.1.121
This paper presents the results of an investigation into the pull-out capacity characteristics of screw anchor piles. Theoretical background of screw anchor pile (SAP) was first discussed. A series of reduced-scale model tests were performed on a number of cases with different SAP geometries such as pitch and diameter of screw as well as relative density of the model ground. The applicability of the pull-out capacity prediction equations were also examined based on the test results. It was shown that the pitch of screw has negligible effect on the pull-out capacity, while the diameter of screw has relatively large effect on pull-out capacity under a given condition. Practical implications of the findings from this study are discussed in great detail.
A Study on Soil Slope Stability Design Considering Seepage Analysis
Kim, You-Seong ; Kim, Jae-Hong ; Lee, Jin-Kwang ; Kim, Seong-Soo ;
Journal of the Korean Geotechnical Society, volume 29, issue 1, 2013, Pages 135~147
DOI : 10.7843/kgs.2013.29.1.135
Most of slope failures are triggered by heavy rainfall during rainy season. If the rain keeps on for the season, the water content of the ground increases and its matric suction decrease, and then the safety factor of soil slope gets lower. The change of water table level for soil slope stability dose not describe the behavior of the soil slope in real situation, hence it may be necessary to modify the design standard for slope stability in association with rain infiltration. For correct design, economical construction, and maintenance of a soil slope, unsaturated flow analysis is needed for estimation of slope instability regarding water infiltration and soil behavior on unsaturated soil slopes. The entire soil slope cannot be saturated by prolonged rainfall and wetting band depth (saturated zone) just deepens from slope surface, hence the cause of the shallow surface slide is the wetting band depth depending on rainfall duration and intensity. Therefore, the paper presents the differences between theoretical equation and numerical analysis for wetting band depth on soil surface and its safety factor, and compares the slope stability obtained from unsaturated flow analysis with that obtained from conventional slope stability analysis.
A Study on Decreasing Behavior of Strength & Elastic Parameters due to Water Infiltration in Rock Cores (III)
Cho, Hong-Je ; Moon, Jong-Kyu ; Jeong, Il-Soo ;
Journal of the Korean Geotechnical Society, volume 29, issue 1, 2013, Pages 149~159
DOI : 10.7843/kgs.2013.29.1.149
This paper deals with behaviors of Poisson's ratio with water content through uniaxial compressive strength against 307 individual rock cores, which are classified into sedimentary, igneous and metamorphic rock. Poissons' ratio demonstrates independent behaviors and does not correlate with mechanical and physical parameter of rocks. The water content behavior of Poissson's ratio represents decrease, increase and random style. Rock samples with decreasing behavior demonstrate absolute preponderance above the 70% level. As Poisson' ratio shows independent behaviors, it should be considered based on experimental results of in-situ rock in the process of design, construction, and supervision.
Analysis of Diameter Effects on Skin Friction of Drilled Shafts in Sand
Lee, Sung-June ;
Journal of the Korean Geotechnical Society, volume 29, issue 1, 2013, Pages 161~170
DOI : 10.7843/kgs.2013.29.1.161
In this paper, numerical pile segment analysis is conducted with an advanced soil elastoplastic model to investigate the diameter effects on skin friction behaviour of a drilled shaft in sand. Ultimate skin friction and 't-z' behavior from the pile segment analyses for drilled shafts show good agreement with those from design methods. Higher ultimate skin friction for the smaller diameter pile is related to the greater increase in the effective radial stress at the interface due to the localized dilation at and near the pile interface. Stiffer t-z curve for the smaller diameter pile is related to the early occurrence of three shear stages (early, dilation, constant volume shear stages). The diameter effects on ultimate skin friction of drilled shafts are more prominent for denser sand and lower confining pressure.
Experimental Validation of the Radial Mapping Rule in Bounding Surface Plasticity Model
Jung, Young-Hoon ; Lee, Ju-Hyung ;
Journal of the Korean Geotechnical Society, volume 29, issue 1, 2013, Pages 171~181
DOI : 10.7843/kgs.2013.29.1.171
The radial mapping rule in bounding surface model was experimentally investigated by analyzing the drained stress probe tests on Chicago clays. The experimental data obtained from 10 drained stress probe paths were analyzed to calculate the directions of the plastic strain increments. The anisotropic bounding surface model was adopted to represent a bounding yield surface which resides in the pre-consolidation yield stress of undisturbed clays. The projection origins were estimated by finding the interceptions of the straight lines passing through the current stress point and the imaginary yield stress point on the bounding surface. The results show that the projection origin is not fixed at a point but moves toward the direction of the stress probe path after it is established around the initial stress point.