• Proceedings of the Korean Geotechical Society Conference
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• 2000.11b
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• pp.139-151
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• 2000

Rockfall protection fence is one of the most common rockfall protection measures in Korea. The fences have been constructed in almost every hazardous cutslopes along national highway in Korea. However, the capability and performance of the fence as rockfall protection system are seldom known since no field test which can provide information on the response and the behavior of fence was carried out. This is the first full scaled rockfall test in Korea. The objectives of the test are to provide the information on the behavior and the capability of fence and to propose the design specifications for the fence. In this test, four different systems have been selected and tested. For each test, the rockfall impact energy was analyzed and the response and behavior of the system were investigated.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.179-190
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• 2006

The water supply tunnel has different characteristics which play a important role in stable water supply to the public from mechanical behavior and maintenance in comparison with road md railway tunnel. In this study, the present state and characteristics of water supply tunnels controlled by K-water have been investigated. The distribution of effective stresses that takes into account the effect of seepage forces induced by internal water pressure are estimated from closed-form and numerical method. The analysis of stress-strain behavior, seepage problem and hydrojacking for ensuring safety of existing water supply tunnel against neighboring new construction has been conducted.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.438-443
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• 2000

A wide range of problems geotechnical engineering have been analyzed by using the finite element method. In order to establish confidence in a numerical procedure, it is desirable that numerical solution be verified against field or laboratory observations, or both, and in order to aid the user in applying the method to practical problems, it is necessary to examine effects of various parameters that influence the behavior of engineering structures. Often it can be profitable to translate numerical solutions in formats that can be used readily for design analysis. The allowable bearing capacity of concrete piles is mainly governed by settlement rather than by strength of soil. Therefore, the load-displacement behavior of piles should be well understood at the design stage. This paper deals with some of these goals by considering the problem of load-displacement behavior of axially-loaded pile foundations.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1181-1192
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• 2008

A laboratory investigation was carried out into effects of strain rate on undrained shear behavior of Holocene clay underneath Kobe Airport with an objective to evaluate the factor of safety of the retaining structure built on it. It was examined in a series of triaxial compression and extension tests performed using different rate of axial straining. A comparative compression test in which the strain rate was changed in steps was also carried out. Similar tests were performed in constant-volume direct shear box (DSB) test. And, the deformation characteristics of the clay were also examined in order to evaluate the variation of stiffness during undrained shearing. It was found that the undrained strength increased with not only the shear rate but also the consolidation period. ISOTACH properties seemed a key to govern the undrained shear behavior.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.219-224
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• 2009

In this study, the characteristics of pullout behavior of Pressurized light-weight steel Anchor was investigated through centrifuge model tests considering pull-out angle $0^{\circ}$ with changing undrained shearstrength(0~1, 2~4, 5~7kPa) of clay. According to the results of tests, the yield pullout load of clay ground was gradually increased up to 30% as undrained shear strength was increased. Therefore, it was known that the yield pullout load was affected by increasing the undrained shear strength, in addition, the pattern of behavior was not changed.

• Geomechanics and Engineering
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• v.18 no.2
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• pp.121-131
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• 2019

This article discusses the phenomenon of plastic volumetric deformation of naturally structured clays before virgin yielding, i.e., subyielding behavior. A simple approach representing both the compression and shear responses of the clays during subyielding is demonstrated. A new compression model for structured clays based on the theoretical framework of the Structured Cam Clay (SCC) model via incorporation of the subyielding behavior is presented. Two stress surfaces are introduced to distinguish the subyielding and virgin yielding. The hardening and destructuring processes of structured clays under isotropic compression and shear are the focus of this work. The simulations of the compression and shear of eleven natural clays are studied for validation. The proposed work can accurately predict the subyielding behavior of structured clays both qualitatively and quantitatively and can be used for modeling structured clays under compression and shear responses in geological and geotechnical engineering problems.

• Geotechnical Engineering
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• v.10 no.4
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• pp.67-82
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• 1994

In this study, a reinforced clay model based on the limit equilibrium of forces under direct shear was proposed to predict shear strength increase in clays induced by the steel inclusion. The model accounted for the effects of orientation of inclusion, length, bonding stress between clay and indclusion and passive soil resistance 1 induced by the inclusion movement, on the behavior of reinforced clays. In order to compare with the theoretical predictions, direct shear tests were performed using a direct shear apparatus formed of an open shear box. Also pull-out tests were conducted to determine the bonding stress between the inclusion and clay. From the experimental results, the increase or decrease in shear strength of reinforced clay samples was found to depend on the orientation of inclusionas well as water content of clay samples. From the comparison of theoretical predictions and experimental results, it was found that the theore tical model predicted reasonably well the influence of orientation of the inclusion as well as passive soil resistance induced by the inclusion movement on the mechanical behavior of reinforced clays.

• Journal of the Korean Geotechnical Society
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• v.15 no.4
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• pp.153-166
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• 1999

Since the reliability of results by the existing analyzing method is low, in the case of for excavation performed in urban area whose stability is of great importance, construction control based on field monitoring is always necessary. But the field monitoring reflects only the behavior of construction process that has already been carried out, and it has limitations in predicting the behavior of the expected construction process, which is practically more important for construction control. In this study, construction control system for excavation which can predict the behavior of the expected processes during construction with high degree of accuracy, is developed by adopting inverse analysis. The inverse analied applied field monitoring results to excavation analysis can improve the reliability of predicted results. The developed system uses an elasto-plastic soil spring model for the excavation analysis and the minimization of least squared errors between measured displacements and calculated displacements for the inverse analysis. All the required processes for construction control can be performed as an integrated work within the system reflecting real time application and user's convenience. Their applicabilitis are confirmed by two case studies.

• Journal of the Korean Geotechnical Society
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• v.32 no.1
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• pp.19-33
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• 2016

Stability analysis based on the limit equilibrium method combined with the result of infiltration analysis is commonly used to evaluate the effect of rainfall infiltration on the slope stability. Soil is a three-phase mixture composed of solid particle, water and air. Therefore, a fully coupled mixture theories of stress-deformation behavior and the flow of water and air should be used to accurately analyze the process of rainfall infiltration through soil slope. The purpose of this study is to study the effect of interaction of air and water flow on the mechanical stability of slope. In this study, stability analyses based on the coupled hydro-mechanical model of three-phases were conducted for slope of weathered granite soil widespread in Korea. During the process of hydro-mechanical analysis strength reduction technique was applied to evaluate the effect of rainfall infiltration on the slope stability. The results showed an increase of air pressure during infiltration because rain water continuously displaced the air in the unsaturated zone. Such water-air interaction in the pore space of soil affects the stress-deformation behavior of slope. Therefore, the results from the three-phase model showed different behavior from the solid-water model that ignores the transport effect of air in the pores.

• Journal of the Korean Geotechnical Society
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• v.20 no.5
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• pp.109-116
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• 2004

The model tests are conducted to assess the behavior characteristics of geogrid reinforced soil walls according to different surcharge pressures and reinforcement spacings. The models are built in the box having dimension, 100cm tall, 140cm long, and 100cm wide. The reinforcement used is geogrid(tensile strength 2.26t/m). Decomposed ganite soil(SM) is used as a backfill material. The strain gauges and LVDTs are Installed to obtain the strain in the reinforcements and the displacements of the wall face. From the results, it can be concluded that the more the reinforcement tensile strength increases, the more the wall displacements and the geogrid strains decreases. The maximum wall displacements and geogrid strains of the model walls occur due to the uniform surcharge pressure at the 0.7H from the bottom of the wall. The horizontal displacements of the wall face nonlinearly increase with the increase of surcharge pressures, and this nonlinear behavior is significantly presented for larger surcharge due to the nonlinear tensile strength-strain relationship of the reinforcements.