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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
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Volume & Issues
Volume 26, Issue 12 - Dec 2010
Volume 26, Issue 11 - Nov 2010
Volume 26, Issue 10 - Oct 2010
Volume 26, Issue 9 - Sep 2010
Volume 26, Issue 8 - Aug 2010
Volume 26, Issue 7 - Jul 2010
Volume 26, Issue 6 - Jun 2010
Volume 26, Issue 5 - May 2010
Volume 26, Issue 4 - Apr 2010
Volume 26, Issue 3 - Mar 2010
Volume 26, Issue 2 - Feb 2010
Volume 26, Issue 1 - Jan 2010
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Development and Verification of Large Triaxial Testing System for Dynamic Properties of Granular Materials
Lee, Sung-Jin ; Kim, Yun-Ki ; Choo, Yun-Wook ; Lee, Sei-Hyun ; Kang, Tae-Ho ;
Journal of the Korean Geotechnical Society, volume 26, issue 12, 2010, Pages 5~17
Coarse granular material is used as important fill material in most of large embankments such as railway, road, dam and so on. Therefore, the accurate design parameters of the coarse granular material are necessarily required in design and construction. The behavior of the coarse granular material was not well understood because of the lack of large testing equipment capable of coarse granular material. A large triaxial testing system was developed in this research, capable of large specimens of 500 mm, 300 mm and 150 mm in diameter. In the new large triaxial testing system, the load cell is installed inside the triaxial cell and axial displacement is measured locally on a specimen in order to improve control and measurement in small strain level. Urethane specimens of 300 mm and 50 mm in diameter were prepared. The large triaxial tests were performed on the 300 mm diameter urethane specimens while RC/TS and impact echo tests on the 50 mm diameter urethane specimens to verify this testing system. In this verification test results, we could ascertain the reasonable test results of the KRRI large triaxial testing system.
Chemical and Physical Influence Factors on Performance of Bentonite Grouts for Backfilling Ground Heat Exchanger
Lee, Chul-Ho ; Wi, Ji-Hae ; Park, Moon-Seo ; Choi, Hang-Seok ; Shon, Byong-Hu ;
Journal of the Korean Geotechnical Society, volume 26, issue 12, 2010, Pages 19~30
Bentonite-based grout has been widely used to seal a borehole constructed for a closed-loop vertical ground heat exchanger in a geothermal heat pump system (GHP) because of its high swelling potential and low hydraulic conductivity. Three types of bentonites were compared one another in terms of viscosity and thermal conductivity in this paper. The viscosity and thermal conductivity of the grouts with bentonite contents of 5%, 10%, 15%, 20% and 25% by weight were examined to take into account a variable water content of bentonite grout depending on field conditions. To evaluate the effect of salinity (i.e., concentration of NaCl : 0.1M, 0.25M, and 0.5M) on swelling potential of the bentonite-based grouts, a series of volume reduction tests were performed. In addition, if the viscosity of bentonite-water mixture is relatively low, particle segregation can occur. To examine the segregation phenomenon, the degree of segregation has been evaluated for the bentonite grouts especially in case of relatively low viscosity. From the experimental results, it is found that (1) the viscosity of the bentonite mixture increased with time and/or with increasing the mixing ratio. However, the thermal conductivity of the bentonite mixture did not increase with time but increased with increasing the mixing ratio; (2) If bentonite grout has a relatively high swelling index, the volume reduction ratio in the saline condition will be low; (3) The additive, such as a silica sand, can settle down on the bottom of the borehole if the bentonite has a very low viscosity. Consequently, the thermal conductivity of the upper portion of the ground heat exchanger will be much smaller than that of the lower portion.
A Study on the Optimum Design of Piled-raft Foundation Considering Pile Head Condition
Cho, Jae-Yeon ; Lee, Sung-June ; Jeong, Sang-Seom ;
Journal of the Korean Geotechnical Society, volume 26, issue 12, 2010, Pages 31~40
This study describes the three-dimensional behavior of pile foundations based on a numerical study. A series of numerical analyses were performed for connectivity conditions between piles and cap under vertical and lateral loadings. It is shown that a fixed connection between pile and cap is able to transfer significant bending moment through the connection and increases the pile lateral stiffness and the bending moment. Based on the results obtained, it was found that the cross sectional shear force in the raft with fixed head condition was larger than that of pinned head condition. Thus, the reinforcement of pile head and thickness of the raft also increases in fixed pile head condition. From the results, it is found that the overall behavior and cross sectional forces of pile foundations is affected significantly by the pile head conditions. Furthermore, the design of pile foundations with pinned head condition was judged to be less costly and very useful for preliminary design stages.
Lateral Behavior of Driven Piles Subjected to Cyclic Lateral Loads in Sand
Paik, Kyu-Ho ;
Journal of the Korean Geotechnical Society, volume 26, issue 12, 2010, Pages 41~50
The behavior of laterally cyclic loaded piles is different from that of piles under monotonic loading and depends on soil and load characteristics. In this study, model pile load tests were performed using a calibration chamber to investigate the effects of load characteristics on the behavior of laterally cyclic loaded piles in sand. Results of the model tests show that the ultimate lateral load capacity of laterally cyclic loaded piles decreases linearly with increasing the number of cycles and increases slightly with increasing the magnitude of cyclic lateral loads. When the piles reach the ultimate state, the maximum bending moment developed in the piles decreases linearly with increasing the number of cycles and it occurs at a depth of 0.36 times pile embedded length for all the number of cycles. However, both the magnitude and depth of the maximum bending moment of piles in the ultimate state increase slightly as the magnitude of cyclic lateral loads increases. It is also observed that the cyclic lateral loading generates a decrease in the ultimate lateral load capacity and maximum bending moment for piles in the ultimate state. In addition, based on the model test results, a new empirical equation for the ultimate lateral load capacity of laterally cyclic loaded piles in dense sand is also proposed. A comparison between predicted and measured load capacities shows that the proposed equation reflects satisfactorily the model test results.
Earth Pressure on a Rigid wall due to Loads Condition and Distance
Oh, Bun-Jin ; Lee, Sang-Duk ;
Journal of the Korean Geotechnical Society, volume 26, issue 12, 2010, Pages 51~60
Earth pressure due to gravity generally increases linearly with the depth, but the distribution of earth pressure due to surface load depends on the loading condition, the ground condition, and the boundary condition. In this study, the earth pressure on a rigid wall due to the vertical surface load was measured in experiments. Rigid wall was built in the model test box, and it was filled with homogeneous sandy ground (width 30 cm, height 88 cm, length 110 cm). Rigid wall was composed of 8 segments, which were tested on the two load cells. In the tests, we observed the distribution of the earth pressure on the rigid wall depending on the vertical surface load and it's location. According to the test results, the lateral earth pressure due to the vertical surface load showed its maximum value at a constant depth and decreased with the depth, to the negligible value at the critical depth. The critical depth and the depth at which lateral earth pressure reaches its maximum were not decided by the magnitude of the vertical surface load. They were dependant on the distance from the rigid wall.
Seismic Response of Stone Column-Improved Soft Clay Deposit by Using 1g Shaking Table
Kim, Jin-Man ; Lee, Hyun-Jin ; Ryu, Jeong-Ho ;
Journal of the Korean Geotechnical Society, volume 26, issue 12, 2010, Pages 61~70
A series of shaking table tests were conducted to estimate the seismic performance of soft ground deposits improved by stone column. The amplification of acceleration, shear strain, and shear wave velocity were evaluated to compare the seismic response of unimproved ground deposits with that of improved ground deposits. From the test results, it was shown that the stone column can prevent large shear deformation in ground deposits. However, it was also found that the acceleration of improved ground deposits may be amplified more than that of unimproved ground deposits when it was subjected to short periodic seismic wave. The results suggest that it is necessary to perform the ground response analysis with model experiments for both unimproved and improved ground deposits to evaluate the effect of stone column on the seismic performance of improved ground deposits.
Estimation of Variability of Soil Properties and Its Application to Geotechnical Engineering Design
Kim, Dong-Hee ; Kim, Min-Tae ; Lee, Chang-Ho ; Lee, Woo-Jin ;
Journal of the Korean Geotechnical Society, volume 26, issue 12, 2010, Pages 71~79
The reliable evaluation of the coefficient of variation (COV) of soil properties is required for the determination of adequate design values and the application of a probabilistic method for the design of geotechnical structures. In this paper, the applicability of methods for estimating the standard deviation, such as the. Three-Sigma Rule and a statistical method, is evaluated by using site investigation data of the Songdo area. It is found that the Three-Sigma Rule provides similar results to those of a statistical method when using
=6 for the property with small variability and
=4.2~5.3 for the property with large variability. It is also observed that, for the undrained shear strength that has an increasing trend with depth, a
value of 4 is adequate for the evaluation of the variability by the Three-Sigma Rule. The COVs of soil properties determined in this paper could be used in the estimation of the confidence interval and characteristic values of soil properties.