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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 22, Issue 12 - Dec 2006
Volume 22, Issue 11 - Nov 2006
Volume 22, Issue 10 - Oct 2006
Volume 22, Issue 9 - Sep 2006
Volume 22, Issue 8 - Aug 2006
Volume 22, Issue 7 - Jul 2006
Volume 22, Issue 6 - Jun 2006
Volume 22, Issue 5 - May 2006
Volume 22, Issue 4 - Apr 2006
Volume 22, Issue 3 - Mar 2006
Volume 22, Issue 2 - Feb 2006
Volume 22, Issue 1 - Jan 2006
Selecting the target year
A Method for Nonlinear Dynamic Response Analysis of Semi-infinite Foundation Using Mapping
Lee Choon-Kil ;
Journal of the Korean Geotechnical Society, volume 22, issue 4, 2006, Pages 5~10
A special finite difference method for nonlinear dynamic response analysis of semi-infinite foundation soil using mapping which transforms semi-infinite domain into finite domain is presented here. For the region of engineering interest, mapping is isometric, and fur far field, shrink mapping which transforms infinite interval into finite interval is adopted. At first, the responses of semi-infinite foundation soil with linear constituting model are computed, and compared with theoretical results and those of existing method. Good agreements are obtained among the results of the proposed method, Lamb's theory and FEM with extensive mesh model. Then the responses of infinite foundation soil are computed by the present method, using small and large mesh model. The results of small and large mesh models agree well with each other, demonstrating the effectiveness of the proposed method.
Method of Estimating Pile Load-displacement Curve Using Bi-directional Load Test
Kwon Oh-Sung ; Choi Yong-Kyu ; Kwon Oh-Kyun ; Kim Myoung-Mo ;
Journal of the Korean Geotechnical Society, volume 22, issue 4, 2006, Pages 11~19
For the last decade, the hi-directional testing method has been advantageous over the conventional pile load testing method in many aspects. However, because the hi-directional test uses a loading mechanism entirely different from that of the conventional pile load testing method, many investigators and practicing engineers have been concerned that the hi-directional test would give inaccurate results, especially about the pile head settlement behavior. Therefore, a hi-directional load test and the conventional top-down load test were executed on 1.5 m diameter cast-in-situ concrete piles at the same time and site. Strain gauges were placed on the piles. The two tests gave similar load transfer curves at various depth of piles. However, the top-down equivalent curve constructed from the hi-directional load test results predicted the pile head settlement under the pile design load to be about one half of that predicted by the conventional top-down load test. To improve the prediction accuracy of the top-down equivalent curve, a simple method that accounts for the pile compression is proposed. It was also shown that the strain gauge measurement data from the hi-directional load test could reproduce almost the same top-down curve.
Behavior of Soft Ground Improved by CSCP and SCP Using Centrifuge Modeling
Ahn Kwang-Kuk ;
Journal of the Korean Geotechnical Society, volume 22, issue 4, 2006, Pages 21~30
In this study, centrifuge model tests were performed to investigate the stress concentration ratio, bearing capacity and deformation modes of piles in clay ground improved by granular piles with two types of pile (CSCP, SCP) and various replacement ratios (0, 20, 40, 60%). According to the results of tests, the load ratio of ground improved by SCP and CSCP proportionally increased as replacement ratio increased. It shows that average normalized load of ground improved by CSCP is higher by about
than by SCP. As a result of rigid loading tests, it was evaluated that average stress concentration ratio of CSCP is higher than that of SCP. Only expansion failure occurred in CSCP, whereas SCP showed the expansion and shear failure simultaneously.
Strength Characteristics of Low Cement Ratio Soil Stabilizer Using Industrial By-products
Cho Jin-Woo ; Lee Yong-Soo ; Yu Jun ; Kim Sei-Ho ;
Journal of the Korean Geotechnical Society, volume 22, issue 4, 2006, Pages 31~39
An experimental investigation was carried out to evaluate the strength characteristics of low cement ratio soil stabilizer. The low cement ratio soil stabilizer has been developed by the replacement of certain part of cement with by-product pozzolanic materials such as blast furnace slag, fly ash, waste gypsum and by using activator. A series of unconfined compressive strength tests were performed to investigate and obtain high-strength composite soil stabilizer with large amounts of blast furnace slag and fly ash. Test results show that there were better properties when blast furnace slag, fly ash, waste gypsum, and activator were added in proper ratio. The replacement of certain part of cement with by-product pozzolanic materials improved the strength and pore structure properties.
High Resolution Seismic Reflection Method Using S-Waves: Case Histories for Ultrashallow Bedrocks
Kim Sung-Woo ; Woo Ki-Han ; Han Myung-Ja ; Jang Hae-Dong ; Choi Yong-Kyu ; Kong Young-Sae ;
Journal of the Korean Geotechnical Society, volume 22, issue 4, 2006, Pages 41~49
This paper demonstrates the feasibility of using shallow S-wave, high-resolution seismic reflection surveys to characterize geological structure and stratigraphy of basement rocks for civil engineering purposes. S-wave seismic reflections from depths less than 20 m were recorded along the top of steep readout slopes. Seismic reflection data were recorded using a standard CDP acquisition method with a 24-channel seismograph and a sledge-hammer SH-wave source. The data were acquired using a split-spread source-receiver geometry with a 2 m shot-and-receiver interval, and then were processed to enhance S/N ratio of the data, to improve resolvable power of the seismic section, and to get velocity information of the basement rock. The final seismic reflection profiles using the CDP technique has imaged surfaces as shallow as less than 1m and resolved beds as thin as 1m. The migrated reflection sections possess sufficient quality to correlate the prominent reflection events to the bedding planes and faults identified on the readout outcrops. Similar S-wave reflection surveys could also be used to produce the necessary details of a geological structure of shallow bedrocks to pinpoint optimum locations for monitor wells of civil engineering purposes.
Characteristic of Shear Behavior of Coarse Grained Materials Based on Large Scale Direct Shear Test (II)
Lee Dae-Soo ; Kim Kyoung-Yul ; Hong Sung-Yun ; Hwang Sung-Chun ;
Journal of the Korean Geotechnical Society, volume 22, issue 4, 2006, Pages 51~59
In this paper, the effect of variation of density and uniformity coefficient on shear strength was analyzed from the results of large scale shear test. In addition, the friction coefficient at critical state per vertical load was estimated using the equation proposed by Wood (1998). The test sample fur the test was obtained from the local quarry sites. Tests results show that the shear strength of
is relatively larger than that of
and uniformity coefficient (5.0) has larger shear strength than that in 10.0. In the meantime, the friction coefficient at critical state shows
according to the test conditions.
Numerical Modeling of Sloping Ground under Earthquake Loading Using UBCSAND Model
Park Sung-Sik ; Kim Young-Su ; Kim Hee-Joong ;
Journal of the Korean Geotechnical Society, volume 22, issue 4, 2006, Pages 61~71
A numerical procedure is presented fur evaluating seismic liquefaction on sloping ground sites. The procedure uses a fully coupled dynamic effective stress analysis with a plastic constitutive model called UBCSAND. The model was first calibrated against laboratory element behavior. This involved cyclic simple shear tests performed on loose sand with and without initial static shear stress. The numerical procedure is then verified by predicting a centrifuge test with a slope performed on loose Fraser River sand. The predicted excess pore pressures, accelerations and displacements are compared with the measurements. The results are shown to be in good agreement. The shear stress reversal patterns depend on static and cyclic shear stress levels and are shown to play a key role in evaluating liquefaction response in sloping ground sites. The sand near the slope has low effective confining stress and dilates more. When no stress reversals occur, the sand behaves in a stiffer manner that curtails the accumulated downslope displacements. The numerical procedure using UBCSAND can serve as a guide for design of new soil structures or retrofit of existing ones.
Stochastic Seepage Analysis of Dam
Cho Sung-Eun ;
Journal of the Korean Geotechnical Society, volume 22, issue 4, 2006, Pages 73~83
Seepage analysis through unsaturated zone based on the theory of unsaturated flow is commonly performed to evaluate dam safety. However, the concepts of unsaturated soil behavior have not been transferred into the hands of practicing geotechnical engineers since the problems involving unsaturated soils often have the appearances of being extremely complex. There is variability and uncertainty associated with the unsaturated hydraulic properties that in turn will lead to variability in predicting unsaturated soil behavior such as seepage rate and the pore water pressure distribution. In this paper, measurements of the soil-water characteristic curve and saturated hydraulic conductivity for the core material of dam were conducted. Then, finite element stochastic analysis was used to capture the effect of unsaturated hydraulic properties on the seepage behavior of dam. It is observed that the amount of seepage increases, as the values of unsaturated soil parameters a and n increase. The values of m and p showed opposite trend.
Changes of Undrained Shear Behavior of Sand due to Cementation
Lee Woo-Jin ; Lee Moon-Joo ; Choi Sung-Kun ; Hong Sung-Jin ;
Journal of the Korean Geotechnical Society, volume 22, issue 4, 2006, Pages 85~94
Triaxial tests at isotropic confining pressure of 200 kPa were carried out to show the undrained shear behavior of artificially cemented sands, which were cemented by gypsum, and the influences of relative density and DOC (degree of cementation) were investigated from the results. The yield strength, the elastic secant modulus at yield point and the peak frictional angle of cemented sands increased abruptly compared to uncemented sands, and it was checked that cementation exerts more influence on the behavior of sand than the relative density. But after breakage of the cementation bonds, the relative density was more important factor on the behavior of sand than the cementation. Because the compressibility md the excess pore pressure of cemented sands were reduced due to the cementation bonds, the effective stress path of cemented sands was going toward to the total stress path of uncemented sands. The cementation of sand restricted the dialtion of sand at the pre-yield condition, but induced more dilation in the post-yield condition.
An Experimental Study on the Load-settlement Behavior and Settlement-reducing Effect of the Disconnected Piled Raft Foundation
Lee Yeong-Saeng ; Hong Seung-Hyeun ;
Journal of the Korean Geotechnical Society, volume 22, issue 4, 2006, Pages 95~104
For the interests in the economical and safe design of foundation system, the concern on the piled raft or disconnected piled raft foundation system is increasing now. In this study, the behavior and the effects of the disconnected piled raft foundation not studied actively in this country were examined using the triaxial compression tests in place of laboratory model tests. The triaxial test samples were prepared with Jumunjin standard sand and the carbon rods, which simulate the ground soil and piles respectively. After the sample in which carbon rods were arranged was laid inside the triaxial chamber, the confining pressure was applied and then loading test was conducted. To analyze the reinforcing effects of the disconnected piled raft foundation, a few number of tests were carried out by changing the number, the diameter and the length of the model piles. As a result of this study, in the disconnected piled raft foundation system, even though the number of pile is few and the diameter of pile is small, the settlement of the foundation system decreased greatly.
Estimation of Kinematic Soil-Structure Interaction for Deeply Embedded Foundations
Kim Seng-Hyun ;
Journal of the Korean Geotechnical Society, volume 22, issue 4, 2006, Pages 105~111
Earthquake strong motion recordings from two deeply embedded sites with instrumented structures and free-field accelerographs are used to evaluate variations between foundation-level and free-field ground motions. The foundation free-field ground motion variations are quantified in terms of frequency-dependent transmissibility function amplitude,
. Comparisons are then performed with an analytical model for the assumed conditions of a rigid base slab and a vertically propagating, coherent incident wave. The limiting assumptions of the model are not strictly satisfactory for actual structures, and the results of the analysis reflect not only incoherence effects, but also possible foundation flexibility and wave inclination effects. Nonetheless, the simple analytical model is in an acceptable agreement with the empirical analysis and appears to be applicable in practice.