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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 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
Selecting the target year
Behavior of H-Type Steel Pile Under Axial Lond in Cohesionless Soils
Hong Sa-Myun ; Lee Yeong-Saeng ;
Journal of the Korean Geotechnical Society, volume 21, issue 8, 2005, Pages 5~12
In early days, to analyze the behavior of single pile under axial load, many assumptions were made and field tests were performed. But in recent days, the development of computers led the use of the numerical analysis resulting in more realistic and correct results. The numerical methods are classified into Load Transfer Method and Elastic Solid Approach. In this study a numerical program applying t-z model to Load Transfer Method suggested by Coyle & Reese was developed. And another finite difference program using matrix based on this load transfer was developed. As a result, it is found that the values of the F.D.M. were similar to the values measured in-situ.
Characteristics of Undrained Cyclic Shear Behavior for the Nak-dong River Sand Due to the Aging Effect
Kim Dae-Man ; Kim Young-Su ; Jung Sung-Gwan ; Seo In-Shik ;
Journal of the Korean Geotechnical Society, volume 21, issue 8, 2005, Pages 13~26
It was known that the aging effect of sands is insignificant in comparison with clays, and hence the study on this effect had seldom been performed prior to the early 1980s. However, field tests for this effect have been actively carried out since it was investigated that penetration resistance of reformed sands increased with the lapse of time. Recently, the aging effect of sands has also been examined in laboratory testings. In this study, undrained static triaxial tests were performed to evaluate the effect on the Nak-dong River sands, with different .elative densities
, consolidation stress ratios
, and consolidation times. As a result of the tests, it was proved that the undrained cyclic shear strength
increased with the aged time on the sands. The in situ range of Rf on the sands, which is applicable to the magnitude of earthquake in the Nak-dong River area, was proposed by using the test results.
A Simple Constitutive Model for Soil Liquefaction Analysis
Park Sung-Sik ; Kim Young-Su ; Byrne P. M ; Kim Dae-Man ;
Journal of the Korean Geotechnical Society, volume 21, issue 8, 2005, Pages 27~35
Several damages due to large displacement caused by liquefaction have been reported increasingly. Numerical procedures based on effective stress analysis are therefore necessary to predict liquefaction-induced deformation. In this paper, the fully coupled effective stress model called UBCSAND is proposed to simulate pore pressure rise due to earthquake or repeated loadings. The proposed model is a modification of the simple perfect elasto-plactic Mohr-Coulomb model, and can simulate a continuous yielding by mobilizing friction and dilation angles below failure state. Yield function is defined as the ratio of shear stress to mean normal stress. It is radial lines on stress space and has the same shape of Mohr-Columob failure envelope. Plastic hardening is based on an isotropic and kinematic hardening rule. The proposed model always causes plastic deformation during loading and reloading but it predicts elastic unloading. It is verified by capturing direct simple shear tests on loose Fraser River sand.
Formulation of Generalized Hoek-Brown Model and Development of Rounded Hoek-Brown Model
Kim Bum-Sang ; Kwon O-Soon ; Jang In-Sung ;
Journal of the Korean Geotechnical Society, volume 21, issue 8, 2005, Pages 37~43
Hoek-Brown model, which was developed in order to predict the behavior of rock mass, has widely been utilized and revised by many researchers to solve various problems encountered in tunnelling and slope stability analysis. However, there is no schematic investigation on the application of the Hoek-Brown model to numerical analysis including finite element simulations. In this paper the Hoek-Brown model was formulated as a constitutive model according to the procedure of generalized plasticity theory, and a Rounded Hoek-Brown model, which could overcome the numerical difficulties by modifying the edge part of the yield surface as a curve shape, was newly proposed. The new model could satisfy the requirements as an elasto-plastic constitutive soil model and follow the yield surface of the original Hoek-Brown model in the compression mode. The constitutive equation for the proposed model herein was established and presented to be applicable to the generalized nonlinear finite element analysis.
Infiltration Analysis for Surficial Stability Evaluation of Two-layered Slopes
Cho Sung-Eun ;
Journal of the Korean Geotechnical Society, volume 21, issue 8, 2005, Pages 45~53
Shallow slope failures in residual soil during periods of prolonged infiltration are common over the world. Therefore, this study examines an approximate method to estimate the influence of infiltration on surficial stability of slopes by one-dimensional infiltration model. Modified GAML model based on the Green-Ampt model was extended to predict the infiltration behavior of two-layered slope. Then, the model has been considered to evaluate the likelihood of shallow slope failure which is induced by a particular rainfall event that accounts for the rainfall intensity and duration for various return periods in two-layered soil profile. The results obtained from the approximate method were compared with those obtained from numerical analyses. According to the results, with the use of properly estimated input parameters, the proposed method was found to give good results that agree reasonably well to those of the more rigorous finite element analyses.
Variation of Dynamic Earth Pressure Due to Sliding of Retaining Walls
Yoon Suk-Jae ; Kim Sung-Ryul ; Hwang Jae-Ik ; Kim Myoung-Mo ;
Journal of the Korean Geotechnical Society, volume 21, issue 8, 2005, Pages 55~61
Mononobe-Okabe method is generally used to evaluate dynamic earth pressure for the seismic design of retaining walls. However, Mononobe-Okabe method does not consider the effects of dynamic interactions between backfill soil and walls. In this research, shaking table tests on retaining walls were performed to analyze the phase and magnitude of dynamic earth pressure. The unit weight of walls, the amplitude of input acceleration and the base friction coefficient of walls were varied to analyze the influence of these factors on the dynamic earth pressure. Test results showed that the dynamic earth pressure was 180 degrees out of phase with the wall inertia force for the low sliding velocity of the wall, whereas small peaks of the dynamic earth pressure, which are in phase with the wall inertia force, were developed for the high sliding velocity of the wall. The amplitude of dynamic earth pressure was proportional to that of wall acceleration and the unit weight of the wall. In addition, the dynamic earth forces calculated by the Mononobe-Okabe method were the upper limit of the dynamic earth pressures.
Seepage Characteristics of Embedded Rock Layer Under the Earth Fill
Lee Haeng-Woo ; Chang Pyoung-Wuck ;
Journal of the Korean Geotechnical Society, volume 21, issue 8, 2005, Pages 63~72
Rocks are dumped to soft marine ground in order to improve trafficability and construction conditions in the tideland reclamation construction sites. Though this rock layer under earth fill has caused in a serious seepage problems after construction, seepage behaviors of this embankment structure is not correctly investigated. Water flow through rock layers is, in general, known as Non-Darcy's flow. However, the embedded rock layer under earth fill is not known whether its flow is governed by Darcy's or Non-Darcy's law. Therefore, a numerical analysis, laboratory model test and filed investigations were performed for analyzing the those seepage characteristics in this research. Results show that there is significance of
of confidence between observed heads and seepage rates, and the calculated ones by SAMTLE which is developed under the assumption that the water flows through the two-layer system obey the Darcy's flow. And after operating the hydraulic gradient(i) of
upon laboratory model, these seepage characteristics of the embedded rock layer show that Reynolds Numbers are less than 10 and the relationship between these velocities of rock layer(v) and hydraulic gradients(i) is linearly proportional with more than 0.79 of the coefficient of correlation
. And the Reynolds Number of the velocity calculated by the relation of v=ki in the embedded rock layer of OO sea dike is
. It shows also laminar flow. Based on these results, it is concluded that the seepage characteristics of embedded rock layer under earth fill can be laminar and Darcy's flow.
Development of Neural Network Model for Estimation of Undrained Shear Strength of Korean Soft Soil Based on UU Triaxial Test and Piezocone Test Results
Kim Young-Sang ;
Journal of the Korean Geotechnical Society, volume 21, issue 8, 2005, Pages 73~84
A three layered neural network model was developed using back propagation algorithm to estimate the UU undrained shear strength of Korean soft soil based on the database of actual undrained shear strengths and piezocone measurements compiled from 8 sites over the Korea. The developed model was validated by comparing model predictions with measured values about new piezocone data, which were not previously employed during development of model. Performance of the neural network model was also compared with conventional empirical methods. It was found that the number of neuron in hidden layer is different for the different combination of transfer functions of neural network models. However, all piezocone neural network models are successful in inferring a complex relationship between piezocone measurements and the undrained shear strength of Korean soft soils, which give relatively high coefficients of determination ranging from 0.69 to 0.72. Since neural network model has been generalized by self-learning from database of piezocone measurements and undrained shear strength over the various sites, the developed neural network models give more precise and generally reliable undrained shear strengths than empirical approaches which still need site specific calibration.
Variations of Coefficient of Earth Pressure at Rest According to Stress Paths for Compacted Residual Soils
Lee Byung-Sik ; Park Sung-Kook ;
Journal of the Korean Geotechnical Society, volume 21, issue 8, 2005, Pages 85~93
Earth pressures acting on unmovable rigid walls vary according to loading-unloading conditions due to compaction experienced by backfill soil. Appropriate coefficients of earth pressure at rest with considering this influence need to be determined to estimate earth pressures more reasonably.0 this study, a single cycle hysteretic model simulating soil's loading-unloading-reloading behavior under
was reproduced by conducting a series of
test for compacted residual soils. Based on the results, coefficients of earth pressure at rest at each stage of stress paths such as, virgin loading, unloading and reloading were determined. Also, applicabilities of empirical equations to the estimation of the coefficients were evaluated by comparing the experimental results with those estimated by the equations. As a result, it was concluded that the empirical equations could be applied reasonably to the estimation of the coefficients for compacted residual soils in cases where some amount of error might be acceptable for the reloading stage of the hysteretic model.
A Stability Analysis of Geosynthetics Reinforced Soil Slopes I. - Slope Stability Analysis Considering Reinforcing Effects -
Kim Kyeong-Mo ; Kim Hong-Taek ; Lee Eun-Soo ; Kim Young-Yoon ; Ahn Kwang-Kuk ;
Journal of the Korean Geotechnical Society, volume 21, issue 8, 2005, Pages 95~105
Generally, a modified version of limit equilibrium method can be used to evaluate a slope stability of the geosynthetic reinforced soil slopes. In most cases, resisting effects of geosynthetic reinforcement are dealt with considering an increased shear strength on the potential slip surface. However, it is not clear that the methods satisfy all three equilibrium equations. As we know, the pattern of normal stress distribution along the slip surface is the key factor in calculating the safety factor of slopes. In this study, the new slope stability analysis method in which not only reinforcing effects of geosynthetics can be considered but also all three equilibrium equations can be satisfied was proposed with assuming the normal stress distribution along the slip surface as quadratic curve with horizontal
. A number of illustrative examples, including published slope stability analysis examples for the reinforced and unreinforced soil slopes, loading test of large scale reinforced earth wall and centrifuge model tests on the geotextile reinforced soil slopes, were analyzed. As a result, it is shown that the newly suggested method yields a relatively accurate factor of safety for the reinforced and unreinforced soil slopes.
A Stability Analysis of Geosynthetics Reinforced Soil Slopes II - Evaluation of Required Reinforcement Tensile Force -
Kim Kyeong-Mo ; Kim Hong-Taek ; Lee Eun-Soo ; Kim Young-Yoon ; Ahn Kwang-Kuk ;
Journal of the Korean Geotechnical Society, volume 21, issue 8, 2005, Pages 107~116
Generally, when the stability of the geosynthetic reinforced soil slopes is analyzed, the required tensile forces of each reinforcement layers are calculated from total reinforcement forces which are necessary to retain the equilibrium state of slip mass in which the slip surfaces are assumed to be a linear or bilinear. It is assumed that the reinforcement forces are increased or constant with depth. However, according to the instrumented field data and laboratory model test results, the maximum tensile strain of reinforcement in a reinforced soil slope is developed in a certain elevation, not a bottom of the slope. In the concept of reinforced soil, postulated failure surfaces are the traces of the position in which the reinforcement tensile forces are maximum in the layer, and the reinforcement tensile forces are related to the stress state on the postulated failure surface. Therefore, in this study, based on the distribution of normal stress on the slip surface, a new method for the evaluation of required tensile forces is suggested and a number of the instrumented field data are analyzed by newly suggested method. As a result, it is shown that the newly suggested method produces relatively accurate reinforcement tension forces.