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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 21, Issue 10 - Dec 2005
Volume 21, Issue 9 - Nov 2005
Volume 21, Issue 8 - Oct 2005
Volume 21, Issue 7 - Sep 2005
Volume 21, Issue 6 - Aug 2005
Volume 21, Issue 5 - Jul 2005
Volume 21, Issue 4 - Jun 2005
Volume 21, Issue 3 - Apr 2005
Volume 21, Issue 2 - Mar 2005
Volume 21, Issue 1 - Feb 2005
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Geotomography Applied for the Integrity Test of Cast-in-place Piles
Lee Jae-Kyung ; Park Jong-Nam ;
Journal of the Korean Geotechnical Society, volume 21, issue 4, 2005, Pages 5~12
Recently, geophysical prospecting methods have played very important roles in civil and environmental engineering problems. Technical advances in geophysical instruments and computer system made it possible to get underground images with very high resolution far purposes to resolve those problems. It was possible partly due to ever increasing demand for development of technologies needed to precisely detect polluted areas and prevent ground-related accidents. Based on the same demand, integrity tests of cast-in place piles draw more attention and development of accurate test procedures is required. Ultrasonic methods is one of most advanced non-destructive procedures. In the paper, a geotomography method is employed for the cast-in place pile integrity test using ultrasonic waves. The image of pile interior is scanned and scrutinized far better and more accurate decision in the cast-in place pile integrity. In this study, we firstly examined the accuracy fur tomography program with idealized synthetic models built in water tank: their position and size were changed in the tank and each case was studied. In the next stage, real concrete pile models were fabricated and images of anomaly areas inside the pile were scanned to successfully locate those areas.
Consolidation Characteristics of Dredged Mixed Soil with Inserted Materials
Yoon Hyun-Suk ; Lee Ki-Ho ; Park Jun-Boum ; Kim Jae-Young ;
Journal of the Korean Geotechnical Society, volume 21, issue 4, 2005, Pages 13~20
In this study, consolidation test and numerical analysis were performed with the aim of investigating the characteristics of consolidation behavior of mixed soil with the amount and particle shape of inserted materials. Mixed soil was made up of matrix (dredged clay) and inserted material (crashed oyster shell and/or sand). The concept of stress share ratio was introduced to evaluate the consolidation characteristics of mixed soils. And the finite differential numerical analysis was carried out by applying the Mikasa's consolidation theory. From the results of experiments and numerical analysis, it was verified that mixed soil consolidation behavior is affected by changes in inserted material. When a similar amount of granular material was inserted, the compressibility of the clay matrix of oyster shell mixed soil was smaller than that of sand mixed soil.
Behaviors of Lightweight Foamed Soils Considering Underwater Curing and Water Pressure Conditions
Yoon Gil-Lim ; You Seung-Kyong ;
Journal of the Korean Geotechnical Society, volume 21, issue 4, 2005, Pages 21~29
Lightweight Foamed Soil (LWFS) could be the substitute of normal soils used in backfill to earth structures and embankment materials far soft ground improvement in port and harbor project because of its effectiveness in settlement reduction and earth pressure decrease due to its lightness. A series of triaxial and unconfined compression tests were performed to investigate behaviors of LWFS composed of dredged soils, cement and air foam, and cured at underwater conditions. The density of LWFS will increase if LWFS is cured at underwater conditions because high water pressure makes air foam disappear or demolish during the curing compared with LWFS cured at normal air conditions. This paper is to find the mechanical behaviors of LWFS cured at seawater depth of 5.0 m and 10.0 m, respectively, which simulates underwater curing conditions by underwater pressure simulator chamber developed during this study. In addition, new normalized factor formula, which takes account of mixing design conditions determining compressive strength of LWFS, was proposed to consider mixing design factor fur LWFS.
A Prediction of Undrained Shear Behavior of the Remolded Weathered Mudstone Soil Using the Constitutive Model
Lee Sang-Woong ; Choo In-Sig ; Kim Young-Su ; Kim Ki-Young ;
Journal of the Korean Geotechnical Society, volume 21, issue 4, 2005, Pages 31~40
This study proposed a new yield function considering the spacing ratio of the critical state to predict the undrained shear behavior of anisotropic field ground. We have suggested a nonassociated constitutive model that used a newly modified plastic potential function in order to apply the yield function of the modified Cam-Clay model to the anisotropic consolidation. In this paper, we predicted undrained shear behavior of the remolded weathered mudstone soils in Phohang isotorpically and anisotropically consolidated using the suggested model. To evaluate the reliability of proposed model, we predictied undrained shear behavior of Bankok Clay isotropically, nomally consolidated and Drammen Clay Ko consolidated. The predicted results are consistent with the observed behavior.
Consolidation and Strength Properties of Clay Subjected to High Temperature Histories
Lee Kang-Il ;
Journal of the Korean Geotechnical Society, volume 21, issue 4, 2005, Pages 41~49
Recently, ground has been often exposed to high temperature environments such as chemical ground improvement, thermal energy storage system, and underground nuclear waste disposal system. Since the behavior of clay is sensitive to temperature change, the studies on the engineering properties of clay subjected to high temperature history may be important. This paper presents the mechanical behavior of clay with high temperature condition.
tests using a high temperature and pressure triaxial compression test apparatus were carried out in order to investigate characteristics of deformation, shear strength, compression and consolidation of clay. During tests, the temperature was varied from
Seismic Techniques for the Integrated Assessment of Structural Integrity of Concrete Runway
Joh Sung-Ho ; Kang Tae-Ho ; Cho Mi-Ra ; Suh Young-Chan ; Kwon Soo-Ahn ;
Journal of the Korean Geotechnical Society, volume 21, issue 4, 2005, Pages 51~63
Concrete pavement may suffer from material deterioration or structural problems, which lead to surface cracks and deflection of a concrete pavement. Degraded concrete pavement, when it is still under operation, should be recovered by an urgent maintenance to avoid the discontinued service leading to the significant traffic problems and economic loss. Seismic techniques are good tools to assess the structural integrity of concrete runway. It is because seismic techniques can evaluate engineering properties nondestructively and quickly and the evaluation can be extended to subgrade. In this study, a series of numerical simulations of stress-wave propagation were performed to verify feasibility of seismic techniques as an assessment tool. Based on the results of the numerical simulation, a framework of using seismic techniques was presented fur the nondestructive integrated assessment fur structural integrity of concrete runway. And the presented framework was applied to
concrete runway with surface cracks, which required urgent maintenance, to identify the causes of the surface cracks. The results obtained from the structural integrity assessment were compared with the measurements of the cores collected from the same runway for verification of the presented framework.
Evaluation of Characteristics of Re-liquefaction Resistance in Saturated Sand Deposits Using 1-g Shaking Table Test
Ha Ik-Soo ; Kim Myoung-Mo ;
Journal of the Korean Geotechnical Society, volume 21, issue 4, 2005, Pages 65~70
Many case histories of re-liquefaction phenomena seem to support the idea that sand deposits, if they once have been liquefied, could be reliquefied again by a subsequent earthquake even though the earthquake is smaller than the previous one. The magnitude of the strains induced in the initial liquefaction has a significant influence on the resistance of the sample to re-liquefaction. The deposits undergoing liquefaction experience large shear strain during liquefaction. And this previous strain changes the microstructure into highly anisotropic structure such as columnlike structure and connected voids. This type of anisotropy is so unstable that it can reduce re-liquefaction resistance. It is blown that the extent of anisotropic structural change depends on the gradation characteristics of ground. The purpose of this study is to estimate the correlation between the gradation characteristics of the sand and the ratio of re-liquefaction resistance to liquefaction resistance. In this study, 1-g shaking table tests were carried out on five different kinds of sands. During the tests the values of excess pore pressure at various depths and surface settlements were measured. Re-liquefaction resistances were not affected by the initial void ratio and the effective confining pressures, and the deposits of all test sands which had once been liquefied were reliquefied in the cyclic loading number below 1 to 1.5. The ratio of re-liquefaction resistance to liquefaction resistance linearly decreased as
increased, and was constant as about 0.2 above the value of
, 0.15 mm.
Evaluation of Stiffness Profile for a Subgrade Cross-Section by the CAP(Common-Array-Profiling)-SASW Technique
Joh Sung-Ho ; Jang Dae-Woo ; Kang Tae-Ho ; Lee Il-Wha ;
Journal of the Korean Geotechnical Society, volume 21, issue 4, 2005, Pages 71~81
Surface wave techniques were initially based on 2-D plane waves and were later improved to the techniques based the 3-D based cylindrical waves. However, body-wave interference, near-field effect and limited technology in surface wave measurements restricted the use of 3-D cylindrical waves to the 1-D evaluation of subgrade stiffness. In this study, by the numerical simulation of SASW measurements, the dispersion properties of surface waves including vertical, horizontal Rayleigh waves and Love waves were thoroughly investigated in the 3-D domain, and a new filter criteria to minimize the near-field effect was established, which led to CAP (common-array-profiling)-SASW technique. The CAP-SASW technique enabled the evaluation of subgrade stiffness fur a specific subgrade segment, not for a whole section of measurement array. Therefore, a contour plot of subgrade stiffness with a ground-truth quality can be obtained by the CAP-SASW technique. The procedure proposed in this study was verified by comparing the shear-wave velocity profiles with the shear-wave velocity profiles of downhole testing at two geotechnical sites.
A Practical App개ach of Stress Path Method for Rational Settlement Estimation of Saturated Clay Deposit : Part I (Evaluation and Use of Characteristic Deformation Behaviors)
Kim Chang-Youb ; Chung Choong-Ki ;
Journal of the Korean Geotechnical Society, volume 21, issue 4, 2005, Pages 83~98
In this paper, a conceptual approach of the stress path method was newly proposed for a rational estimation of settlements of saturated clay deposits. In the proposed approach, settlement-related characteristic deformation behaviors of a specific clay deposit, which can cover all probable stress changes expected in the field, are experimentally evaluated in advance. Then settlements of various structures constructed on the deposit are easily estimated with only the characteristic deformation behaviors and without any additional experimental effort. In Part I of this paper, in order to provide practicality to the new conceptual approach, we developed a detailed procedure which is capable of evaluating characteristic deformation behaviors of a saturated clay deposit with only a limited number of tests and easily predicting deformations under a given stress change using the characteristic deformation behaviors. The applicability of the developed procedure was clearly shown by presenting an actual application example.
A Practical Approach of Stress Path Method for Rational Settlement Estimation of Saturated Clay Deposit : Part II (Settlement Estimation Procedure and Application Examples)
Kim Chang-Youb ; Chung Choong-Ki ;
Journal of the Korean Geotechnical Society, volume 21, issue 4, 2005, Pages 99~114
In Part I of this paper, a conceptual approach of the stress path method was newly proposed for a rational estimation of settlements of saturated clay deposits. A detailed procedure for effective evaluation and use of settlement-related characteristic deformation behaviors was developed in order to provide practicality to the new approach. In this Part II, on the basis of the results of Part 1, the concept of the new approach was embodied in the form of a detailed settlement estimation procedure. The applicability and usefulness of the new procedure were strongly supported by various application examples. In addition, possible errors of other conventional settlement estimation methods were investigated by comparing with the new procedure. Because of its flexible applicability for wide range of field conditions, the new procedure will have great usefulness in the practical side. For example, a reasonable foundation design based on allowable settlement criteria can be easily performed and modification of design factors can be readily reflected even during the subsequent construction stage. Especially, the new procedure will be of great use for preliminary work in a large scale construction site where various structures are planned to be constructed on a nearly identical ground condition.
Development of Slope Stability Analysis Method Based on Discrete Element Method and Genetic Algorithm I. Estimation
Park Hyun-Il ; Park Jun ; Hwang Dae-Jin ; Lee Seung-Rae ;
Journal of the Korean Geotechnical Society, volume 21, issue 4, 2005, Pages 115~122
In this paper, a new method composed of discrete element method and genetic algorithm has been introduced to estimate the safety factor and search critical slip surface on slope stability analysis. In case of estimating the safety factor, conventional methods of slope analysis based on the limit equilibrium do not satisfy the overall equilibrium condition; they must make assumptions regarding the inclination and location of the interstice forces. An alternative slope analysis method based on the discrete element method, which can consider the compatibility condition between force and displacement, is presented. Real-coded genetic algorithm is applied to the search for the minimum factor of safety in proposed analysis method. This search method is shown to be more robust than simple optimization routines, which are apt to find local minimum. Examples are also shown to demonstrate the applicability of the proposed method.
Application and Verification of Coupled Analysis of Piled Piers
Won Jin-Oh ; Jeong Sang-Seom ;
Journal of the Korean Geotechnical Society, volume 21, issue 4, 2005, Pages 123~134
A coupled three-dimensional pile group analysis method (YSGroup) was developed considering nonlinear pile head stiffness matrices and compared with other analytical methods (elastic displacement method, Group 6.0 and FBPier 3.0). In this method, a pile cap was modelled by four-node flat shell element, a pier was modelled using 3 dimensional beam element, and individual piles were modelled as beam-column elements. Through the comparative studies on a piled pie. subjected to lateral loads in linear soil, it was found that present method (YSGroup), elastic displacement method and Group 6.0 gave similar results of lateral pile head displacement, but FBPier 3.0 was estimated to show somewhat larger displacements than those from the three methods. Displacements of superstructure (pier), including nonlinear soil behavior, could be estimated by present method (YSGroup) and FBPier 3.0 because these two methods modelled the superstructure directly by finite element techniques. It was found that pile groups in pinned pile head condition had a tendency to cause excessive rotation of the pile cap.
Geosynthetic Reinforced Segmental Retaining Wall Failure Buying Heavy Rainfall - A Case Study
Yoo Chung-Sik ; Jeon Han-Yong ; Jung Hye-Young ; Jung Hyuk-Sang ;
Journal of the Korean Geotechnical Society, volume 21, issue 4, 2005, Pages 135~143
This paper presents a case history of a geosynthetics-reinforced segmental retaining wall, which collapsed during a severe rainfall immediately after the completion of the wall construction. In an attempt to identify possible causes for the collapse, a comprehensive investigation was carried out including physical and strength tests on the backfill, stability analyses on the as-built design based on the current design approaches, and slope stability analyses with pore pressure consideration. The investigation revealed that the inappropriate as-built design and the bad-quality backfill were mainly responsible for the collapse. This paper describes the site condition including wall design, details of the results of investigation and finally, lessons learned. Practical significance of the findings from this study is also discussed.
Joint Diversion Analysis Using the Dispersion Characteristics of Love Wave and Rayleigh Wave (I) - Constitution of Joint Diversion Analysis Technique -
Lee Il-Wha ; Joh Sung-Ho ;
Journal of the Korean Geotechnical Society, volume 21, issue 4, 2005, Pages 145~154
Love wave and Rayleigh wave are the major elastic waves belonging to the category of the surface wave. Those waves are used to determine the ground stiffness profile using their dispersion characteristics. The fact that Love wave is not contaminated by P-wave makes Love wave superior to Rayleigh wave and other body waves. Therefore, the information that Love wave carries is more distinct and clearer than that of others. Based on theoretical research, the joint inversion analysis that uses the dispersion information of both Love and Rayleigh wave was proposed. This analysis consists of the forward modeling using transfer matrix, the sensitivity matrix for evaluating the ground system and DLSS (Damped Least Square Solution) as an inversion technique. The technique of joint inversion uses the dispersion characteristics of Love wave and Rayleigh wave simultaneously making the sensitivity matrix. The sensitivity matrix was used for inversion analysis repeatedly to find the approximate ground stiffness profile. The purpose of the joint inversion analysis is to improve accuracy and convergency of inversion results by utilizing that frequency contribution of each wave is different.
Joint Inversion Analysis Using the Dispersion Characteristics of Love Wave and Rayleigh Wave (II) - Verification and Application of Joint Inversion Analysis -
Lee Il-Wha ; Joh Sung-Ho ;
Journal of the Korean Geotechnical Society, volume 21, issue 4, 2005, Pages 155~165
Love wave and Rayleigh wave are the major elastic waves belonging to the category of the surface wave. Those waves are used to determine the ground stiffness profile using their dispersion characteristics. The fact that Love wave is not contaminated by P-wave makes Love wave superior to Rayleigh wave and other body waves. Therefore, the information that Love wave carries is more distinct and clearer than that of others. Based on theoretical research, the joint inversion analysis that uses the dispersion information of both Love and Rayleigh wave was proposed. Numerical analysis, theoretical model test, and field test were performed to verify the joint inversion analysis. Results from 2D, 3D finite element analysis were compared with those from the transfer matrix method in the numerical analysis. On the other hand, the difference of results from each inversion analysis was investigated in the theoretical model analysis. Finally, practical applicability of the joint inversion analysis was verified by performing field test. As a result, it is confirmed that considering dispersion information of each wave simultaneously prevents excessive divergence and improves accuracy.