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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 20, Issue 9 - Dec 2004
Volume 20, Issue 8 - Oct 2004
Volume 20, Issue 7 - Sep 2004
Volume 20, Issue 6 - Aug 2004
Volume 20, Issue 5 - Jul 2004
Volume 20, Issue 4 - Jun 2004
Volume 20, Issue 3 - Apr 2004
Volume 20, Issue 2 - Mar 2004
Volume 20, Issue 1 - Feb 2004
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New Observational Design and Construction Method in Tunnels and Its Application to Very Large Cross Section Tunnel
Hwang Jae-Yun ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 5~14
The observational design and construction method in tunnels is becoming important recently. In many tunnels, enormous cost and time are consumed to cope with the failing or sliding of rock blocks, which could not be predicted because of the complexity of rock discontinuities. It is difficult to estimate the properties of rock masses before the construction. In this paper, a new observational design and construction method in tunnels are proposed, and then applied to the example of the very large cross section tunnel based on actual discontinuity information observed in situ. The items examined in developing a program for the new observational design and construction method are the following ones: generality, precision, high speed, and friendly usability. At the very large cross section tunnel, 7 key blocks were judged to be unstable because they could not be supported by standard supports. Supplementary supports were installed to these 7 key blocks before the excavation. It is possible to detect key blocks all along the tunnel exactly by using the numerical analysis program developed for the new observational design and construction method in the very large cross section tunnel. This computer simulation method with user-friendly interfaces can calculate not only the stability of key blocks but also the design of supplementary supports.
GIS-based Loss Estimation and Post-earthquake Assessment of Building Damage
Jeon Sang-Soo ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 15~24
This paper describes a GIS-based assessment of residential building damage caused by the 1994 Northridge earthquake in which the fractions of existing buildings damaged at various percentages of replacement cost are related to a range of seismic parameters. The assessment uses data from safety inspection reports and tax assessor records, both of which were geocoded and linked to seismic parameters derived from strong motion records at 164 different sites. The paper also describes a GIS-based pattern recognition algorithm for identifying locations of most intense building damage. The algorithm provides a framework for rapidly screening remote sensing data and dispatching emerging services.
Case History Evaluation of Axial Behavior of Micropiles
Jeon Sang-Soo ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 25~32
This paper examines the results of full-scale field tests on micropiles and side resistance is evaluated with respect to axial displacements and soil properties. Both cohesive and cohesionless soils are included in this evaluation. For all practical purposes, the developed load-displacement relationship and the geotechnical soil properties for each micropile and soil type can be used to represent the available data well through normalized average values and empirical correlations. There is a significant difference in load-carrying capacity between micropiles and drilled shafts that results primarily from the micropile pressure-grouting installation effects on the state of stress in the ground. The results show that micropiles can have a significant increase of capacity over larger-diameter drilled shafts at shallower depths with D/B < 100 or so. In cohesive soils, the typical increase is on the order of 1.5 with values as high as 2.5. For cohesionless soils, the typical increases are in the range of 1.5 to 2.5 with values as high as 6.
Damage Estimation Based on Spatial Variability of Seismic Parameters Using GIS Kriging
Jeon Sang-Soo ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 33~44
This paper is focused on the spatial variability of measured strong motion data during earthquake and its relationship with the performance of water distribution pipelines and residential buildings. Analyses of strong motion and the correlations of peak ground velocity (PGV) and pipeline and building damage were conducted with a very large geographical information system (GIS) database including the relationship of time and earthquake intensity and the measured location, and Kriging spatial statistics. Kriging was used to develop regressions of pipeline repair rate (RR) and residential building damage ratio (DR) associated with
confidence peak ground velocity (PGV). Such regressions using Kriging provide an explicit means of characterizing the uncertainty embodied in the strong motion data compared with other spacial statistics such as inverse distance method.
Size Effect of Specimen and Aggregate on Fracture Characteristics of Cemented Sand
Kim Tae-Hoon ; Lee Kang-Il ; Im Eun-Sang ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 45~55
In the past it has been often observed that the shear stresses at failure are much smaller than the shear strength obtained from traditional laboratory tests and conventional analysis technique is inadequate in stiff soil, such as cemented sand. Many researchers have brought attention to the fact that the presence of flaws i.e. fissures, cracks, joints have a great effect on the strength and overall stress-strain behavior of such materials. They have thought that fracture mechanics may appropriately be adopted as a good tool for analysis of these materials. However, the use of fracture mechanics concept especially for cemented sands is faced with difficulties in obtaining relevant parameters, because fracture parameters and predictions are highly dependent on the material constituents and the size of specimens as well as the size of particles. This paper addresses the effects of sizes which include specimen and aggregate on fracture properties of cemented sand. The results of laboratory tests show that the sizes of specimens and particle have a great effect on the fracture properties such as nominal strength of cemented sand.
Lateral Earth Pressure Caused by Action on Earth Retaining Wall in Clay Foundation Ground with Consideration of Construction Speed
Im Eun-Sang ; Lee Kang-Il ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 57~68
When an embankment is constructed on soft clay ground, the lateral displacement generally called as lateral flow is generated in the foundation ground. It strongly affects stabilities of structures, such as foundation piles and underground pipes, in and on the foundation ground. The lateral earth pressure induced by the lateral flow is influenced by the magnitude and construction speed of embankment, the geometric conditions and geotechnical characteristics of the embankment, and the foundation ground, and so on. Accurate methods for estimating the lateral earth pressure have not ever been established because the lateral flow of a foundation ground shows very complicated behavior, which is caused by the interaction of shear deformation and volumetric deformation. In this paper, a series of model tests were carried out in order to clarify effects of construction speed of an embankment on the lateral earth pressure in a foundation ground were design. It was found that the magnitude and the distribution of the lateral earth pressure and its change with time are dependent on the construction speed of the embankment. It was found that a mechanism for the lateral earth pressure was generated by excess pore water pressure due to negative dilatancy induced by shear deformation under the different conditions of construction speeds of embankments.
Back Analysis of Field Measurements Around the Tunnel with the Application of Genetic Algorithms
Kim Sun-Myung ; Yoon Ji-Sun ; Jun Duk-Chan ; Yoon Sang-Gil ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 69~78
In this study, the back analysis program was developed by applying the genetic algorithm, one of artificial intelligence fields, to the direct method. The optimization process which has influence on the efficiency of the direct method was modulated with genetic algorithm. On conditions that the displacement computed by forward analysis for a certain rock mass model was the same as the displacement measured at the tunnel section, back analysis was executed to verify the validity of the program. Usefulness of the program was confirmed by comparing relative errors calculated by back analysis, which is carried out under the same rock mass conditions as analysis model of Gens et at (1987), one of back analysis case in the past. We estimated the total displacement occurring by tunnelling with the crown settlement and convergence measured at the working faces in three tunnel sites of Kyungbu Express railway. Those data measured at the working face are used for back analysis as the input data after confidence test. As the results of the back analysis, we comprehended the tendency of tunnel behaviors with comparing the respective deformation characteristics obtained by the measurement at the working face and by back analysis. Also the usefulness and applicability of the back analysis program developed in this study were verified.
Prediction of Creep Behavior for Cohesive Soils
Kim Dae-Kyu ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 79~89
An elastic-plastic-viscous constitutive model was proposed based on a simple formulation scheme. The anisotropic modified Cam-Clay model was extended for the general stress space for the plastic simulation. The generalized viscous theory was simplified and used for the viscous constitutive part. A damage law was incoporated into the proposed constitutive model. The mathematical formulation and development of the model were performed from the point of view that fewer parameters be better employed. The creep behaviors with or without creep rupture were predicted using the developed model for cohesive soils. The model predictions were favorably compared with the experimental results including the undrained creep rupture, which is an important observed phenomenon for cohesive soils. Despite the simplicity of the constitutive model, it performs well as long as the time to failure ratio of the creep rupture tests is within the same order of magnitude.
Ultrasonically Enhanced Liquid Flow through Porous Media and Variance of Influencing Factors
Kim Young-Uk ; Yang Sung-Jae ; Khim Jee-Hyeong ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 91~98
This paper presented results of the laboratory tests conducted to investigate ultrasonically enhanced flow rate using specially designed and fabricated equipment. Influencing factor,
was verified to investigate the effect of ultrasound on soil matrix and flowing liquid. The test conditions involve soil types, temperature and ultrasonic energy. The test results indicate that ultrasound enhances the flow rate significantly. The degree of enhancement and the values of influencing factors, however, vary with test conditions.
Consolidation Test Method Considering Sample Deformation Due to Stress Release by Sampling
Kim Jae-Young ; Takada Naotoshi ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 99~105
When a saturated clay is sampled from a borehole in an undisturbed manner, the exerted negative pore water pressure restricts the volume expansion. The vertical and horizontal stresses to which the clay was subjected in the ground are smaller and larger than this isotropically confining stress equivalent to the mean principal stress in the ground, respectively. Therefore the sample expands vertically and shrinks laterally under an undrained condition. In the ordinary consolidation test, the sample thus deformed is trimmed to fit the inside of the consolidometer ring. Thus, the specimen generates larger consolidation displacement due to confining larger horizontal stress when in-situ effective pressure is loaded. The specimen does not reproduce the in-situ consolidation behavior, In this paper, considering sample deformation, the test specimen is made to expand laterally to fit the inside of the ring in the undrained manner when the in-situ effective pressure is loaded. And applicability of this proposed test procedure was verified; results from the conventional consolidation test procedure are also discussed.
Bearing Capacity of Shallow Foundation on Geosynthetic Reinforced Sand
Won Myoung-Soo ; Ling Hoe I. ; Kim You-Seong ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 107~117
A series of model tests were conducted to investigate how the number of reinforcement layers, stiffnesses, types of reinforcement material and buried depth of a flexible pipe can affect bearing capacity-settlement curve at a loose sand foundation. In the test results, whereas the type of failure in unreinforced sand was local shear, the type of failure, for model tests with more than 2 reinforcement layers in loose sand, was general shear: The number of the optimum reinforcement layers was found to be two: Stiffness and type of reinforcement were more important than the maximum tensile strength of reinforcement in improving bearing capacity. When the depth of buried pipe from the sand surface was less than the width of the footing, test results showed that both bearing capacity and ultimate bearing capacity of buried pipe in unreinforced sand significantly decreased, and the type of failure in the reinforced sand changed from general shear to local shear.
Effects of Facing Types and Construction Procedures on the Stability of Reinforced Earth Wall
Lim Yu-Jin ; Jung Jong-Hong ; Park Young-Ho ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 119~126
A small-scale reinforced earth wall was constructed in a laboratory to investigate the effect of wall rigidity and of construction sequence on the wall. A full continuous wall facing and a discrete wall facing were designed and constructed for tests. These two different facing systems should adapt different construction procedures due to their different facing shapes. The model wall was built with geo-grid reinforcement, sand, and facings on rigid surface. The model wall was instrumented with earth pressure gages, LVDTs, and strain gages. The experimental results have shown differences in wall behavior related to construction sequence and types of wall facing. It is found in this study that the reinforced earth wall built with full continuous facing is safer than the reinforced earth wall built with the discrete wall facing.
A Study on Magnitude Scaling Factors and Screening Limits of Liquefaction Potential Assessment in Moderate Earthquake Regions
Park Keun-Bo ; Park Young-Geun ; Choi Jae-Soon ; Kim Soo-Il ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 127~140
Conventional methods for the assessment of liquefaction potential were primarily for areas of severe earthquake zones (M=7.5) such as North America and Japan. Detailed earthquake related researches in Korea started in 1997, including development of the seismic design standards for port and harbour structures, which was later completed in 1999. Because most contents in the guidelines were quoted through literature reviews from North America and Japan, which are located in strong earthquake region, those are not proper in Korea, a moderate earthquake region. This requires further improvement of the present guidelines. Considering earthquake hazard data in Korea, use of laboratory tests based on irregular earthquake motion appears to be effective to reflect the dynamic characteristics of soil more realistically than those using simplified regular loading. In this study, cyclic triaxial tests using irregular earthquake motions are performed with different earthquake magnitudes, relative densities, and fines contents. Assessment of liquefaction potential in moderate earthquake regions is discussed based on various laboratory test results. Effects of these components on dynamic behavior of soils are discussed as well. From the test results, screening limits and magnitude scaling factors to determine the soil liquefaction resistance strength in seismic design were re-investigated and proposed using normalized maximum stress ratios under real irregular earthquake motions.
Dependency of Compatibility Termination Criteria on Prehydration and Bentonite Quality for Geosynthetic Clay Liners
Lee Jae-Myung ; Shackelford Charles D. ; Choi Jae-Soon ; Jung Moon-Kyung ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 141~158
The dependency of criteria used to terminate compatibility tests on the prehydration and quality of bentonite in geosynthetic clay liners (GCLs) is evaluated based on permeation with chemical solutions containing 5, 10, 20, 50, and 100 mM calcium chloride (
). The hydraulic conductivity tests are not terminated before chemical equilibrium between the effluent and the influent chemistry has been established, resulting in test durations ranging from < 1 day to > 900 days, with longer test durations associated with lower
concentrations. The evaluation includes both physical termination criteria (i.e., volumetric flow ratio and steady hydraulic conductivity based on ASTM D 5084,
pore volumes of flow, constant thickness of specimen) and chemical termination criteria requiring equilibrium between influent and effluent chemistry (viz., electrical conductivity, pH, and
concentrations). For specimens permeated with 5, 10, and 20 mM
solutions, only the criterion based on chemical equilibrium in
concentration correlates well with equilibrium in hydraulic conductivity, regardless of prehydration or quality of bentonite. However, all of the termination criteria, except for the volumetric flow ratio and 2 pore volumes of flow for the prehydrated specimens, correlate well with equilibrium in hydraulic conductivity regardless of prehydration or quality of bentonite when permeated with 50 and 100 mM
solutions. The results illustrate the uniqueness of the termination criterion based on solute concentration equilibrium between the effluent and the influent with respect to both prehydration and quality of bentonite in the GCLs.
Influence of Rainfall-induced Wetting on Unsaturated Weathered Slopes
Jeong Sang-Seom ; Kim Jae-Hong ; Park Seong-Wan ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 159~169
Surface failures of slopes in weathered soil are caused by infiltration due to prolonged rainfall. These failures are mainly triggered by the deepening of the wetting band accompanied by a decrease in suction induced by the infiltrating water. This paper reports trends of rainfall-induced wetting band depth in two types of weathered soils that are commonly found in Korea. Both theoretical and numerical analyses are presented based on the soil-water characteristic curve (SWCC) obtained using filter paper as well as tensiometer tests. It is found that the magnitude of wetting front suction plays a key role in the stability of slopes in weathered soils. Theoretical analysis based on modified Green and Ampt model tends to underestimate the wetting band depth for typical Korean weathered soils. It was also deduced that for Korean weathered soils, the factor of safety drops rapidly once the wetting band depth of 1.2 m is reached.
Modeling of the Tensile Strength of Unsaturated Granular Soil Using Soil-water Characteristic Curve
Kim Tae-Hyung ; Kim Chan-Kee ; Kim Tae-Hoon ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 171~181
This study was conducted to explore the tensile strength models in granular soil at the full range of unsaturated state. Direct tension experiments were carried out with a newly developed direct tension technique. The measured experimental data were compared with theoretical models developed by Rumpf and Schubert for monosized ideal particulate solids at the unsaturated state. To do this, the soil-water characteristic curve obtained from a suction-saturation experiment was used to define the unsaturation state and the negative pore water pressure with different water content levels, which are important factors in theoretical tensile strength models. The nonlinear behavior of the tensile strength for unsaturated granular soil at the pendular state is appropriately simulated with Rumpf's model. For the funicular and capillary states, the predicted trend by Schubert's model is properly matched with the experimental data: tensile strength steadily increases and reaches a maximum value and then decreases until it reaches zero. This comparison supports the concept that the tensile strength of unsaturated real granular soil can be approximately simulated with theoretical models.
Study on Lond Transfer Characteristics of Sand Compaction Piles in Soft Soil Deposits
Kim Jaekwon ; Kim Soo-Il ; Jung Sang-Seom ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 183~196
Sand Compaction Pile (SCP) is a soft-ground improvement technique used for not only accelerating consolidation but also increasing bearing capacity of soils. In this study, laboratory tests and 3-D finite element analysis were peformed to investigate the characteristics of load transfer in SCP with an emphasis on free-strain behavior of piles with low replacement ratios in the range of 30 to
. Through these focused tests and numerical analyses, we proposed a simplified method to analyze the load transfer characteristics of SCP in soft ground. Moreover, it was shown that estimated normal stresses in SCP using the proposed method were in a reasonable agreement with actual values.
Stability Analysis and Design of the Pretension Soil Nailing System
Park Si-Sam ; Kim Hong-Taek ; Choi Young-Geun ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 197~206
The ground anchor support system may not be occasionally used because of space limitations in urban excavation sites nearby the existing structures. In this case, soil nailing system with relatively short length of nails could be efficiently adopted as an alternative method. The general soil nailing support system, however, may result in excessive deformations particularly in an excavation zone of the existing weak subsoils. Pretensioning the soil nails then could play important roles to reduce deformations mainly in the upper part of the nailed-soil excavation system as well as to improve local stability. In this study, a newly modified soil nailing technology named as the PSN (Pretension Soil Nailing), is developed to reduce both facing displacements and ground surface settlements in top-down excavation process as well as to increase the global stability. Up to now, the analytical procedure and design technique are proposed to evaluate maximum pretension force and stability of the PSN system. Also, proposed are techniques to determine the required thickness of a shotcrete facing and to estimate probability of a failure against the punching shear, Based on the proposed procedure and technique, effects of the radius of a influence circle and dilatancy angle on the thickness of a shotcrete facing, bonded length and safety factors are analyzed. In addition, effects of the reduction of deformations expected by pretension of the soil nails are examined in detail throughout an illustrative example and the
program analysis. And a numerical approach is proposed PSN system using the shear strength reduction technique with the
Analysis on the Geo-reinforced Slope Using Upper Bound Theory
Choi Sang-Ho ; Kim Jong-Min ; Yu Nam-Jae ;
Journal of the Korean Geotechnical Society, volume 20, issue 7, 2004, Pages 207~215
In this study, the upper bound theory is applied to a reinforced slope to develop an limit state analysis method. As processing of this upper bound theory in formulating finite element, the basic idea of numerical method can be obtained from a macroscopic point of view with an anisotropic homogeneous material. The reinforced soil strength reliability depends on properties of reinforcements which consist of the interaction of interfaces between back fill and reinforcements. Both soil's mechanical property and overall behaviour of reinforced soil can be controlled via arranging geometry and relative proportions of reinforced soil. Therefore, the upper bound theory can not only predict the particular limit state action of reinforced soil slope but also is efficiently able to estimate the local plastic failure.