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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 25, Issue 12 - Dec 2009
Volume 25, Issue 11 - Nov 2009
Volume 25, Issue 10 - Oct 2009
Volume 25, Issue 9 - Sep 2009
Volume 25, Issue 8 - Aug 2009
Volume 25, Issue 7 - Jul 2009
Volume 25, Issue 6 - Jun 2009
Volume 25, Issue 5 - May 2009
Volume 25, Issue 4 - Apr 2009
Volume 25, Issue 2 - Feb 2009
Volume 25, Issue 1 - Jan 2009
Selecting the target year
Evaluation of Preconsolidation Stress Considering Small-Strain Shear Wave Velocity
Yoon, Hyung-Koo ; Lee, Chang-Ho ; Kim, Joon-Han ; Lee, Jong-Sub ;
Journal of the Korean Geotechnical Society, volume 25, issue 5, 2009, Pages 5~16
Preconsolidation stress is one of the important design parameters in soft soils because the behavior of saturated soft soils changes dramatically at the preconsolidation stress. For the estimation of preconsolidation stress, the global vertical settlement without considering micro strain behavior has been considered. The purpose of this study is to propose and verify a new method called the "shear wave velocity method" for determination of the preconsolidation stress reflecting on particle behavior at the small-strain. In this study, the undisturbed soft soils obtained at Busan, Incheon and Gwangyang in Korea were used. The oedometer cell incoporated with the bender elements is used for the consolidation tests under the
condition. The preconsolidation stress determined by the proposed method is compared with that estimated by Casagrande (e-log p'), Sridharan (log (1+e)-log p'), and Onitsuka (In(1+e)-log p') methods. This study suggests that the shear wave velocity method may determine simply the preconsolidation stress with considering the small-strain behavior.
Model Tests on Deformation Behavior of Soft Ground Under Embankment
Lee, Kwang-Wu ; Cho, Sam-Deok ; Hong, Won-Pyo ;
Journal of the Korean Geotechnical Society, volume 25, issue 5, 2009, Pages 17~28
When embankments are constructed on soft clay deposit, unsymmetrical surcharges due to embankments may generate the excessive vertical settlement and lateral deformation of soft clay foundation. The excessive deformations in soft grounds cause not only stability problem of the embankment itself but also that of the adjacent structures. The objectives of this research are to study the deformational behavior of soft ground due to the embankment load with different loading and soil conditions. Five model tests are carried out with different test conditions. From the results of the model tests, it is concluded that the lateral displacement induced by the embankment load occurs in the range of two times of the embankment width from a toe. In addition, the relationship between loading rate, v, and the vertical settlement of the soft ground,
, and the lateral displacement at the toe of embankment,
, is investigated based on the model test results.
The Analysis of the Mechanical Characteristic of Bamboo Net
Yang, Kee-Sok ; Lee, Song ;
Journal of the Korean Geotechnical Society, volume 25, issue 5, 2009, Pages 29~37
Examining the mechanical characteristic of the bamboo net structure is necessary in order to evaluate the influence of bending rigidity of bamboo on bearing capacity, however, there is no equipment to examine such mechanical behavior of the bamboo net structure in the world. In this study, a specific equipment to examine stress-strain behavior characteristics of the structure of bamboo net is developed. In comparison with Bamboo's stress-strain behavior characteristic and vertical stress caused by various dozer equipments, the case of estimating minimum embedded depth considering ground settlement is analyzed.
Analysis of Monitoring Results and Back Analysis for Rigid Diaphragm Wall Supported by Ground Anchor
Lee, Jong-Sung ; Hwang, Eui-Suk ; Cho, Sung-Hwan ; Lee, Jun-Hwan ;
Journal of the Korean Geotechnical Society, volume 25, issue 5, 2009, Pages 39~46
In this study, behavior of a rigid continuous wall, earth pressure distribution with construction stage, and axial force of earth anchors were evaluated based on field monitoring data and numerical analysis results. For this purpose, a construction site excavated using the diaphragm wall was selected and full instrumentation system was introduced. From monitoring results, it was found that the values of horizontal displacement of the wall measured from the inclinometers, which were installed within the diaphragm wall were similar to analytical value. The earth pressure increased with excavation progress due to jacking force of the ground anchors installed in previous excavation stages. When the excavation depth reached 60% of the final depth, observed earth pressure distribution was similar to that estimated from Peck's apparent earth pressure distribution. When the excavation depth was around 90% of the final depth, values of observed earth pressure showed middle values between those of Peck's and Tschebotarioffs apparent earth pressures. It was also observed that, when excavation depth is deep, values of the earth pressures from the rigid wall were similar to those estimated from conventional earth pressure distribution shape proposed for flexible walls.
Evaluation of Sand Replacement Method for Determination of Soil Density
Park, Sung-Sik ; Choi, Hyun-Seok ;
Journal of the Korean Geotechnical Society, volume 25, issue 5, 2009, Pages 47~52
A sand replacement method is commonly used to determine the density of the compacted soils. The density of the test or compacted soil is computed on the assumption that the calibration container has approximately the same size or volume and allows the sand to deposit approximately in the same way as a test hole in the field. The sand filling process is simulated in the laboratory and its effect on the determination of density is investigated. Artificially-made holes with different heights and bottom shapes are prepared to simulate various shapes of the test hole in the field. Three sands with different gradations are used in the testing to examine how sand grain size influences the determination of density in the field. As the height of a test hole increases, the error between known density and calculated density decreases, regardless of the types of test hole and sand used. The results of this study can be used to reevaluate and revise the test method for soil density by the sand replacement method.
Reliable Assessment of Rainfall-Induced Slope Instability
Kim, Yun-Ki ; Choi, Jung-Chan ; Lee, Seung-Rae ; Seong, Joo-Hyun ;
Journal of the Korean Geotechnical Society, volume 25, issue 5, 2009, Pages 53~64
Many slope failures are induced by rainfall infiltration. A lot of recent researches are therefore focused on rainfall-induced slope instability and the rainfall infiltration is recognized as the important triggering factor. The rainfall infiltrates into the soil slope and makes the matric suction lost in the slope and even the positive pore water pressure develops near the surface of the slope. They decrease the resisting shear strength. In Korea, a few public institutions suggested conservative slope design guidelines that assume a fully saturated soil condition. However, this assumption is irrelevant and sometimes soil properties are misused in the slope design method to fulfill the requirement. In this study, a more relevant slope stability evaluation method is suggested to take into account the real rainfall infiltration phenomenon. Unsaturated soil properties such as shear strength, soil-water characteristic curve and permeability for Korean weathered soils were obtained by laboratory tests and also estimated by artificial neural network models. For real-time assessment of slope instability, failure warning criteria of slope based on deterministic and probabilistic analyses were introduced to complement uncertainties of field measurement data. The slope stability evaluation technique can be combined with field measurement data of important factors, such as matric suction and water content, to develop an early warning system for probably unstable slopes due to the rainfall.
The Characteristics of Stress Distribution on Two-arch Tunnel's Pillar due to Surface Loads in the Discontinuous Rock Mass
Kim, Hong-Moon ; Lee, Sang-Duk ;
Journal of the Korean Geotechnical Society, volume 25, issue 5, 2009, Pages 65~73
Large scale model tests and numerical analyses are performed to investigate the stress distribution of pillar due to surface loading nearby two-arch tunnel which is constructed in the regularly jointed rocks. It is observed that the influence of discontinuities on the stress distribution in the discontinuous rock mass and the underground stresses induced by surface loading are greater than those of linear elastic theory. Especially, lines of equal stresses are developed to the direction of inclination according to the inclined grade. In cases of discontinuities imbedded in parallel with or vertical to the ground, the pressure bulbs are formed symmetrically, however, the inclined ones result in stress distribution in parallel with and vertical to the planes of discontinuities. Results indicated that stress distribution is seriously affected by the angle of discontinuity. When stresses propagating to the pillar need to be estimated, relative location of surface loading, grade of discontinuous plane, and location of two-arch tunnel should be carefully considered.
Elastic Wave Characteristics According to Cementation of Dissolved Salt
Eom, Yong-Hun ; Truong, Q. Hung ; Byun, Yong-Hoon ; Lee, Jong-Sub ;
Journal of the Korean Geotechnical Society, volume 25, issue 5, 2009, Pages 75~86
Salt, one of the most common soluble materials in engineering soil, may have an effect on mechanical behaviors of soils under its cementation process. In order to investigate this natural phenomenon, non-soluble material by using glass beads is mixed with salt electrolyte and cemented by using oven to evaporate water. Three different sizes of glass bead particles, 0.26, 0.5, and 1.29 mm, with different salt concentration, 0, 0.1, 0.2, 0.5, 1.0, and 2.0M, are explored by using P- and S-waves, excited by bender elements and piezo disk elemets, respectively. The velocities of the P-wave and S-wave of the particulate medium cemented by salt show three stages with the degree of saturation: 1) S-wave velocities increase while P-wave velocities reduce with degree of saturation changing from 100% to 90%; 2) Both velocities are stable with degree of saturation varying from 90% to 10%; 3) The velocities change enormously when the specimens are nearly dry with degree of saturation from 10% to 0%. Besides, the resonance frequencies of S-wave show similar stages to the S-wave velocities. This study demonstrates meaningful trends of elastic wave characteristics of geo-materials according to the cementation of dissolved salt.