• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.55-64
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• 2002

This paper presents a brief review of flexible retaining structure and the most significant methods developed to predict their behavior on underground excavations. Some observations are made about the future directions that the design of retaining systems may take , as there are still some problems where uncertainity exists, in soil-structure interaction and evaluation of strength parameters etc. And also reviewed papers presented in 2002 Fall National Conference of KGS.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.85-95
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• 2002

A substantial portion of the cost of deep excavations in urban environments is devoted to prevent ground movements and their effects on adjacent buildings and utilites. Prediction of ground movements and assessment of the risk of damage to adjacent structures has become an essential part of the planning, design, and construction of a deep excavation project in the urban environments. This paper presents damage assessment techniques for buildings and utilities adjacent deep excavation, which can be readily used in practice.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.271-278
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• 2002

Recently, deep excavation for high-rise buildings occurs frequently to accommodate the rapidly increasing population in urban area. The stability of the earth retaining structures for deep excavation becomes more critical. The behavior of the earth retaining structures should be accurately predicted in a design stage, but the predicted behavior is different from the measured data due to uncertain soil properties and problems in construction. In this study the back-analysis using Powell's optimization theory was performed to match the measured deflection and results obtained from back-analysis were presented.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.79-86
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• 2002

Rock mass classifications form the back bone of the empirical design approach and are widely employed in rock engineering. In this paper the inter-relations were discussed among RMR, Q-system, RCR, N, M-RMR, RMi, and L-RMR. Several relationships for the assessment of the modulus of deformation of rock mass, Poisson's ratio, uniaxial compressive strength, tensile strength, cohesion and internal friction angle were also analysed and suggested.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2003.03a
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• pp.1-12
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• 2003

지반조사 결과에 의거하여 돌리네와 공동이 존재하는 지역을 구분하여 지역에 적합한 카르스트 형식을 적용, 예측하였다. 특히, 터널이 돌리네 발달 가능성이 적은 백운산 지역을 통과하는 경우에 소규모의 KT-1 ∼ KT-5가 존재하는 것으로 예측되었다. 그러나 설계시 지반조사의 한계성을 인식하고 시공 중에 필요하다고 판단되는 구간에는 막장 전방의 지질상태를 파악할 수 있는 조사를 선 시행하여, 그 결과를 토대로 최종 등급을 결정하여 안전한 시공에 대처할 수 있도록 해야 한다.

• Journal of the Korean GEO-environmental Society
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• v.17 no.10
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• pp.33-43
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• 2016

The determination of in-situ capping materials is one of the most important factors to design in-situ capping in order to protect capping materials from erosion. Previous studies have established relationship between the velocity induced by wave energy and effective diameter of sediments, but they are mostly empirical and numerical researches which is too complicated for field engineers to analyze the erosion of in-situ capping materials. This study provides simple analytical solutions and reliability based on hydraulic model test results. Experimental results show that measured flow velocities with respect to depth induced by wave energy are almost the same as estimated velocities and the erosion resistances of the different effective particle diameters can be estimated.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.109-118
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• 2005

It is a very difficult task to estimate engineering properties of the ground when designing underground structures, especially in tunnelling. Therefore, a feed-back system to combine the data measured in construction field with priorly estimated information at the design stage is necessary. In this paper, 3-dimensional back-analysis in tunnelling, to which only relative convergence is applied as input values, is carried out to estimate the optimum geotechnical parameters. For this purpose, the Extended Bayesian Method (EBM), which appropriately combines the objective information with the subjective one, is applied to optimize engineering parameters and 3-dimensional numerical analysis is carried out to predict a trend of relative convergence occurrence. The data measured from two tunnelling sites are used to verify the applicability of the proposed back-analysis technique. from the results of analysis, the proposed back-analysis technique is verified.

• Journal of the Korean Geotechnical Society
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• v.21 no.1
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• pp.43-50
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• 2005

Jet grouting method is widely being used in many geotechnical problems, especially for the purpose of reinforcement of clayey ground and cut-off wall of sandy ground. However, its design depends on highly empirical method, in which many researches have been undertaken. This study investigated the effect of cavitation on jet grouting. Small-scaled model tests were carried out using specially designed and fabricated device to analyze the effect of cavitation on jet grouting with various test conditions including ground condition, injection pressure, and injection time. The test results show that cavitation has a significant effect on jet grouting, and it has a potential for engineering application.

• Tunnel and Underground Space
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• v.28 no.4
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• pp.293-303
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• 2018

Monitoring is the act of collecting and analyzing accurate engineering information using various methods and instruments. The purposes of the monitoring are design verification, construction management, quality control, safety management, and diagnose of structure etc.. The diagnose evaluation of the geotechnical structures corresponds to the confirmation of the structural performance. It is aimed to judge the soundness of geotechnical structures considering the degree of damage due to the environmental change and elapsed time. Recently, microseismicity, which is widely known in Korea, can be used for safety management and diagnoses of structure as it detects the micro-damage without disturbance of the structure. This report provides guideline on the procedure for assessing an underground oil storage cavern using microseismic monitoring techniques. Guidelines cover the selection of monitoring systems, sensor array, sensor installation and operation of systems, and interpretation.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1466-1483
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• 2008

This paper discusses the development of an up-to-date computerized CPT (Cone Penetration Test) based soil engineering classification system to provide geotechnical engineers with a handy tool for their daily design activities. Five CPT soil engineering classification systems are incorporated in this effort. They include the probabilistic region estimation and fuzzy classification methods, both developed by Zhang and Tumay, the Schmertmann, the Douglas and Olsen, and the Robertson et al. methods. In the probabilistic region estimation method, a conformal transformation is used to determine the soil classification index, U, from CPT cone tip resistance and friction ratio. A statistical correlation is established between U and the compositional soil type given by the Unified Soil Classification System (USCS). The soil classification index, U, provides a soil profile over depth with the probability of belonging to different soil types, which more realistically and continuously reflects the in-situ soil characterization, which includes the spatial variation of soil types. The CPT fuzzy classification on the other hand emphasizes the certainty of soil behavior. The advantage of combining these two classification methods is realized through implementing them into visual basic software with three other CPT soil classification methods for friendly use by geotechnical engineers. Three sites in Louisiana were selected for this study. For each site, CPT tests and the corresponding soil boring results were correlated. The soil classification results obtained using the probabilistic region estimation and fuzzy classification methods are cross-correlated with conventional soil classification from borings logs and three other established CPT soil classification methods.