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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Geotechnical Society
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Journal DOI :
Korean Geotechical Society
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Volume & Issues
Volume 28, Issue 12 - Dec 2012
Volume 28, Issue 11 - Nov 2012
Volume 28, Issue 10 - Oct 2012
Volume 28, Issue 9 - Sep 2012
Volume 28, Issue 8 - Aug 2012
Volume 28, Issue 7 - Jul 2012
Volume 28, Issue 6 - Jun 2012
Volume 28, Issue 5 - May 2012
Volume 28, Issue 4 - Apr 2012
Volume 28, Issue 3 - Mar 2012
Volume 28, Issue 2 - Feb 2012
Volume 28, Issue 1 - Jan 2012
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Evaluation of Ground Thermal Conductivity by Performing In-Situ Thermal Response test (TRT) and CFD Back-Analysis
Park, Moonseo ; Lee, Chulho ; Park, Sangwoo ; Sohn, Byonghu ; Choi, Hangseok ;
Journal of the Korean Geotechnical Society, volume 28, issue 12, 2012, Pages 5~15
DOI : 10.7843/kgs.2012.28.12.5
In this study, a series of CFD (Computational Fluid Dynamics) numerical analyses were performed in order to evaluate the thermal performance of six full-scale closed-loop vertical ground heat exchangers constructed in a test bed located in Wonju. The circulation HDPE pipe, borehole and surrounding ground formation were modeled using FLUENT, a finite-volume method (FVM) program, for analyzing the heat transfer process of the system. Two user-defined functions (UDFs) accounting for the difference in the temperatures of the circulating inflow and outflow fluid and the variation of the surrounding ground temperature with depth were adopted in the FLUENT model. The relevant thermal properties of materials measured in laboratory were used in the numerical analyses to compare the thermal efficiency of various types of the heat exchangers installed in the test bed. The simulation results provide a verification for the in-situ thermal response test (TRT) data. The CFD numerical back-analysis with the ground thermal conductivity of 4 W/mK yielded better agreement with the in-situ thermal response tests than with the ground thermal conductivity of 3 W/mK.
Application of Modelling Stress-Strain Relations (Part I) -Application to Plane Strain Compression Tests-
Park, Choon-Sik ;
Journal of the Korean Geotechnical Society, volume 28, issue 12, 2012, Pages 17~25
DOI : 10.7843/kgs.2012.28.12.17
FEM requires the stress-strain relationship equations for numerical analyses. However, most formulations for the stress-strain relationship published up to the present are not satisfactory enough to properly express all the levels from the small strain to the peak. Tatsuoka and Shibuya (1991) suggested a new single formulation applicable not only to a wide range of geo-materials from soft clay to soft rock, but also to a wide range of strain levels from
. The plain strain compression test is carried out to seven samples of research standard sand specimens and two samples of glass beads, which have been used at world-renowned research institutes. In this study, strains of the maximum principal stress (
) and the minimum principal stress (
) were thoroughly measured from
, and the result, applied to Tatsuoka and Shibuya`s new formulation, coincided closely with the measured data of the stress-strain relationship from the small strain to the peak.
Evaluation on Field Application of Controlled Low-Strength Materials Made of Coal Ash in Reclamation Site
Kong, Jin-Young ; Jung, Hyuk-Sang ; Cho, Sam-Deok ; Kim, Ju-Hyong ; Hyun, Jae-Hyuk ; Chun, Byung-Sik ;
Journal of the Korean Geotechnical Society, volume 28, issue 12, 2012, Pages 27~39
DOI : 10.7843/kgs.2012.28.12.27
This paper presented the strength and environmental characteristics of reclaimed-ground filled with controlled low-strength materials (CLSM) made of coal ash, small amounts of cement, and water in a reclamation site and evaluated the possibility of the use of coal ash on reclamation materials for beneficial use. Three-month period of SPT, CPT, environmental effects evaluation etc. were conducted. N values and cone resistances in ground filled with CLSM were greater than or similar to those in dredging sand. In case of land filled with coal ash except cement these values were lower than those in dredging sand. The results of soil and seawater pollution were lower than test criteria without high pH. Also the values of PH test were measured between pH 5.0~9.0, the criteria of industrial water in the Law for the Underground Water of Korea.
Void Ratio Evaluation of Unsaturated Soils by Compressional and Shear Waves
Byun, Yong-Hoon ; Cho, Se-Hyun ; Yoon, Hyung-Koo ; Choo, Yun-Wook ; Kim, Dong-Su ; Lee, Jong-Sub ;
Journal of the Korean Geotechnical Society, volume 28, issue 12, 2012, Pages 41~51
DOI : 10.7843/kgs.2012.28.12.41
Soils are commonly unsaturated in the near surface. The stiffness of soils is affected by the amount of air and water. The objective of this study is to evaluate the porosity of the unsaturated soils by using the elastic waves including compressional and shear waves. The elastic waves are measured at different degrees of saturation by controlling the matric suction. Thus, the unsaturated soils are characterized at different levels of the matric suction. Shear and compressional waves are measured by using the bender elements and the piezo disk elements, respectively. Both transducers are installed on the walls of the rectangular cell. The unsaturated soils are prepared by using uniform size sands and silts. Test results show that both compressional and shear wave velocities change according to the matric suction. The elastic modulus, the shear modulus, and the Poisson`s ratio are estimated based on the measured elastic wave velocities. In addition, the void ratio of the unsaturated soils estimated using elastic wave velocities matches well with the volume based void ratio. This study demonstrates that the elastic waves can be effectively used for the characterization of unsaturated soils.
Dynamic Deformation Characteristics of Joomunjin Standard Sand Using Cyclic Triaxial Test
Kim, You-Seong ; Ko, Hyoung-Woo ; Kim, Jae-Hong ; Lee, Jin-Gwang ;
Journal of the Korean Geotechnical Society, volume 28, issue 12, 2012, Pages 53~64
DOI : 10.7843/kgs.2012.28.12.53
In this study, the modified cyclic triaxial tests with Joomunjin standard sand are performed for dynamic deformation characteristics, such as Young`s moduli and damping ratio. The cyclic triaxial test is equipped with Local Displacement Transducer (LDT) on the outside of a cell which has a range from
of shear strains,
(%), instead of conventional cyclic triaxial test which has linear variable displacement transducer (LVDT) with low precision. With the small strain control, tests were carried out at various loading rates, void ratios, and effective confining pressures. Based on the test results, such as dynamic deformation characteristics, shear modulus, and damping ratio, it is found that the test can measure more range of medium strains (0.02-0.2%) than results obtained from conventional test (resonant column test). For the medium strain range, dynamic deformation characteristics investigated by the cyclic triaxial test are also different from those predicted by nonlinear model in conventional test.
Probabilistic Seepage Analysis Considering the Spatial Variability of Permeability for Layered Soil
Cho, Sung-Eun ;
Journal of the Korean Geotechnical Society, volume 28, issue 12, 2012, Pages 65~76
DOI : 10.7843/kgs.2012.28.12.65
In this study, probabilistic analysis of seepage through a two-layered soil foundation was performed. The hydraulic conductivity of soil shows significant spatial variations in different layers because of stratification; further, it varies on a smaller scale within each individual layer. Therefore, the deterministic seepage analysis method was extended to develop a probabilistic approach that accounts for the uncertainties and spatial variation of the hydraulic conductivity in a layered soil profile. Two-dimensional random fields were generated on the basis of the Karhunen-Lo
ve expansion in a manner consistent with a specified marginal distribution function and an autocorrelation function for each layer. A Monte Carlo simulation was then used to determine the statistical response based on the random fields. A series of analyses were performed to verify the application potential of the proposed method and to study the effects of uncertainty due to the spatial heterogeneity on the seepage behavior of two-layered soil foundation beneath water retaining structure. The results showed that the probabilistic framework can be used to efficiently consider the various flow patterns caused by the spatial variability of the hydraulic conductivity in seepage assessment for a layered soil foundation.
Examination of the Relationship between Average Particle Size and Shear Strength of Granite-derived Weathered Soils through 2-D Distinct-element Method
Kim, Seon-Uk ; Lim, Heui-Dae ;
Journal of the Korean Geotechnical Society, volume 28, issue 12, 2012, Pages 77~86
DOI : 10.7843/kgs.2012.28.12.77
We have carried out a series of numerical experiments to study the effect of average particle size on the mechanical properties of granite-derived weathered soils. A distinct-element method was adopted to study the changes in macro-scale mechanical properties with particle size and maximum-to-minimum particle size ratio. The numerical soil specimen with cohesion values of 0.25 MPa and internal friction angle of 29 degrees was prepared for reference. While keeping the porosity values constant, we varied particle size and size distribution to study how cohesion and internal friction angle changes. The experimental results show that the values of cohesion apparently decrease with increasing particle size. Changes in the values of internal friction angles are small, but there is a trend of increase in internal friction angle as the average particle size increases. This study demonstrates a possibility that the results of numerical experiments of this type may be used for rapid estimation of mechanical properties of granite-derived weathered soils. For example, when mechanical properties obtained through in situ tests and particle size data obtained through lab analysis are available for a site, it is expected that the mechanical properties of weathered granite soils with varying degrees of weathering (thus, varying particle size) may be estimated rapidly only with particle size data for that site.
A Study on the Development and the Verification of a Sonar Sensor System of a Socket Roughness Measurement Device for A Lagre-diamter Drilled Shaft
Jeon, Byeong-Han ; Choi, Yong-Kyu ;
Journal of the Korean Geotechnical Society, volume 28, issue 12, 2012, Pages 87~98
DOI : 10.7843/kgs.2012.28.12.87
A sonar sensor system of a new socket roughness profiling system (SRPS) which can measure the socket roughness of the large-diameter drilled shafts under the in-situ condition was developed and verified. In model tests, the salinity, temperature, and high-turbidity have been changed for simulating the in-situ borehole water conditions. From the test results, it was found that the sonar sensor can measure the distance within an accuracy of 1mm. Because of the wave form characteristics of sonar sensor, the relative error exists in case of the inclined and curved surface, however, the shape of specimen was confirmed relatively exactly using the developed sonar sensor. Moreover, the salinity, temperature, and high-turbidity did not affect the measured data of socket roughness.
An Experimental Study on the Stability of Inclined Earth Retaining
Seo, Min-Su ; Im, Jong-Chul ; Jeong, Dong-Uk ; Yoo, Jae-Won ; Koo, Young-Mo ; Kim, Gwang-Ho ;
Journal of the Korean Geotechnical Society, volume 28, issue 12, 2012, Pages 99~110
DOI : 10.7843/kgs.2012.28.12.99
Inclined Earth Retaining Structure Method (IER method, briefly) is developed in order to improve the existing earth retaining method. In IER method, there are three main structures, front support, back support, and head binding. Especially, back support acts the role that reduces the earth pressure acting on the front support. In this study, the stability according to the installation angle and stiffness of front or back support is analysed by model tests. By the test results, it is known that inclined back support is very effective to reduce the earth pressure acting on the front support. Especially, the effect of the stiffness and installation angle of back support is analysed.
Application of Resistivity Seismic Flat Dilatometer (RSDMT) System for Multiple Evaluation of the Soft Soil Site
Bang, Eun-Seok ; Kim, Young-Sang ; Park, Sam-Gyu ; Kim, Dong-Soo ;
Journal of the Korean Geotechnical Society, volume 28, issue 12, 2012, Pages 111~122
DOI : 10.7843/kgs.2012.28.12.111
Resistivity seismic dilatometer (RSDMT) system is introduced. The resistivity module for obtaining resistivity-depth plot and seismic module for obtaining wave velocity-depth plot are attached to the conventional flat dilatometer testing equipment. To enhance the reliability and repeatability of seismic part in RSDMT, automatic testing system including automatic surface source, PC based data acquisition system and operating program was constructed. To obtain real resistivity value of soil, geometric factor for the array of electrodes in RSDMT was derived empirically. The verification studies for the developed RSDMT system were performed with SPT, CPTu, bender element test and DC resistivity survey. Through one penetration of RSDMT, various soil parameters were obtained and the reliability and repeatability of developed RSDMT system could be checked.
A Study on the Estimation of Slope Stability under the Influence of the Vertical Direction Seismic Coefficient Using Lower Bound Analysis
Choi, Sang-Ho ; Kim, Jong-Min ; Kim, Yong-Soo ;
Journal of the Korean Geotechnical Society, volume 28, issue 12, 2012, Pages 123~131
DOI : 10.7843/kgs.2012.28.12.123
Recent earthquake records indicate that the vertical component of earthquake loading, generally neglected in seismic slope stability analysis, has a significant influence on the stability. This is particularly true for the earthquakes originating inside the continent, not from its boundaries. Therefore the design of geotechnical structures without consideration of vertical component of earthquake loading may result in unsafe design. In this study, with a consideration of the effect of vertical seismic loading, the horizontal yield seismic coefficients under various slope conditions are estimated, using the lower bound limit analysis. In addition, the equation for the determination of the critical direction (either upward or downward) of vertical seismic loading is proposed.