• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.715-719
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• 2009

In this study, a method to predict the consolidation behavior of soft clays and marine clays was developed by combining the equation of Terzaghi's 1-dimensional consolidation and CPTu dissipation. The special attention was given to the consolidation anisotropy due to the difference between 1-D consolidation and radial consolidation of CPTu dissipation. The analysis combining two equations enables direct application of CPTu results. And above all it doesn't require to sample undisturbed specimens and determine consolidation coefficient which is both costly and time consuming and often contains measuring error. It is also advantageous that CPTu test can be carried out any position and any depth. Clays typically have a greater horizontal permeability, $k_h$, than vertical permeability, $k_v$, and the coefficient of consolidation in the horizontal direction is generally higher than the vertical direction. Various data of horizontal and vertical consolidation coefficient ratio were collected and analyzed to develop and verify the method.

• 한국농공학회지
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• 제44권6호
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• pp.106-114
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• 2002

In this study, the results of a series of consolidation test for undisturbed Ariake clay in Japan were analyzed by three methods, e-log p (e: void ratio, p: consolidation pressure), log e-log p and n-log p (n: porosity). Moreover, the characteristics of each analysis method were studied. For undisturbed Ariake clay, the log o-Log p and the n-log p relationships can be found as two groups of straight lines of different gradients, but both the elastic consolidation and plastic consolidation regions of e-log p relationship are expressed as a curve. In this paper, the porosity of consolidation yield n$\_$y/, consolidation yield stress p$\_$y/, and the gradient of the plastic consolidation region C$\_$p/ were represented by the log e-log p method, and n$\_$c/, P$\_$cn/ and C$\_$cn/ were represented by the n-log p method. The meaning and the relationships of each value were studied, and the interrelationships among compression indices i.e. C$\_$cn/, C$\_$p/ and C$\_$c/ are obtained from each analysis method as a function of initial porosity n$\_$0/.

• 한국지반공학회논문집
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• 제16권4호
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• pp.149-156
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• 2000

해성점토를 이용하여 준설매립한 부지의 장기적인 침하거동을 규명하기 위하여 실린더와 대형토조를 이용하여 침강.자중압밀시험을 수행하였으며, 준설매립단지에 자동무선계측시스템을 설치하여 매립부지의 층별침하량과 간극수압의 변화를 계측하였다. 이를 이용하여 준설매립 공정에 따른 매립지층의 침하거동을 분석하고 유한변형률 압밀이론을 이용한 수치해석 결과와 비교하였다. 침하거동 분석결과, 불연속 준설매립공정으로 인하여 매립지층의 분리 현상이 발생하였고 지층별 침하거동이 상이하게 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.216-223
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• 2005

The coefficient of consolidation has been evaluated using the conventional oedometer tests based on the one-dimensional consolidation theory. In the field, however, the actual response of the soil will be subject to the three-dimensional condition during consolidation. In this research, a new estimation method of the coefficient of consolidation for the various stress-deformation conditions was proposed. The good agreement between the computed dissipation of pore pressure and the measured data confirms the usefulness and the applicability of the proposed method to predict the exact rate of consolidation.

• 한국지반환경공학회 논문집
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• 제8권2호
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• pp.49-55
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• 2007

연직배수공법의 적용시 시간경과에 따른 지반의 압밀도를 판단하는 것은 매우 중요하다. 이에 압밀속도를 예측하는 여러 압밀분석해들이 제안되고 있다. 하지만, 실제 현장에서의 압밀속도는 연직배수재의 압밀해석에 의한 값과 상당한 차이를 나타내고 있다. 본 논문에서는 PBD공법을 적용한 부산지역의 대심도 연약지반에 대한 압밀종료시점의 현장계측자료 및 지반조사 자료를 바탕으로 시공 전 압밀분석해로 사용되고 있는 Hansbo, Onoue, Zeng과 Xie의 압밀분석 이론식의 압밀도와 현장에서 계측된 압밀도를 상호 비교, 분석하여 각 압밀분석해의 적용성과 타당성을 평가하였다.

• 한국지반공학회논문집
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• 제21권3호
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• pp.141-148
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• 2005

연약지반의 불균질성, 시료의 교란, 토질상수의 입력오차, 압밀이촌의 단점 등으로 예측된 압밀침하량 및 시간은 대부분 실측치와 잘 일치하지 않고 있다. 따라서 압밀기간동안 계측자료를 활용한 침하량 예측기법은 실무에서 매우 유용한 수단이라 할 수 있다. 본 논문에서는 예측기법으로 많이 활용되는 방곡선법, 아사오카범, 호시노법을 비롯한 최근에 제안된 4법의 이론적 공통점을 바탕으로 아사오카법을 제외한 나머지 분석기법들에 대하여 일반화된 쌍곡선 형태의 수식화 작업으로 새로운 분석 기법을 제안하였으며, 사례를 통하여 유용한 계측분석기법으로 적용성을 확인하였다.

• Smart Structures and Systems
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• 제7권4호
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• pp.289-302
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• 2011

In marine clay deposits, naturally formed or artificially reclaimed, the evaluation and monitoring of the consolidation process has been a critical issue in civil engineering practices due to the time frame required for completing the consolidation process, which range from several days to several years. While complementing the conventional iconographic method suggested by Casagrande and recently developed in-situ techniques that measure the shear wave, this study suggests an alternative experimental procedure that can be used to evaluate the consolidation state of marine clay deposits using the shear wave velocity. A laboratory consolidation testing apparatus was implemented with bimorph-type piezoelectric bender elements to determine the effective stress-shear wave velocity (${\sigma}^{\prime}-V_s$) relationship with the marine clays of interest. The in-situ consolidation state was then evaluated by comparing the in-situ shear wave velocity data with the effective stress-shear wave velocity relationships obtained from laboratory experiments. The suggested methodology was applied and verified at three different sites in South Korea, i.e., a foreshore site in Incheon, a submarine deposit in Busan, and an estuary delta deposit in Busan. It is found that the shear wave-based experimental procedure presented in this paper can be effectively and reliably used to evaluate the consolidation state of marine clay deposits.

• Geomechanics and Engineering
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• 제35권4호
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• pp.385-393
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• 2023

To analyze the consolidation with horizontal sand drains, the plane strain consolidation model under multi-ramp loading is established, and its corresponding analytical solution is derived by using the separation of variables method. The proposed solution is verified by the field measurement data and finite element results. Then, the effects of the loading mode and stress distribution on consolidation and dissipation of pore pressure are investigated. At the same time, the influence of hydraulic conductivity and thickness of sand blankets on soil consolidation are also analyzed. The results show that the loading mode has a significant effect on both the soil consolidation rate and generation-dissipation process of pore water pressure. In contrast, the influence of stress distribution on pore pressure dissipation is obvious, while its influence on soil consolidation rate is negligible. To guarantee the fully drained condition of the sand blanket, the ratio of hydraulic conductivity of the sand blanket to that of clay layer k_d/k_v should range from 1.0×10⁴ to 1.0×10⁶ with soil width varying from 100 m to 1000 m. A larger soil width correspondingly needs a greater value of kd/kv to make sure that the pore water can flow through the sand blanket smoothly with little resistance. When the soil width is relatively small (e.g., less than 100 m), the effect of thickness of the sand blanket on soil consolidation is insignificant. And its influence appears obvious gradually with the increase of the soil width.

• Coupled systems mechanics
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• 제8권6호
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• pp.523-535
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• 2019

Artificial Intelligence (AI) is anticipated to be the future of technology. Hence, AI has been applied in various fields over the years and its applications are expected to grow in number with the passage of time. There has been a growing need for accurate, direct, and quick prediction of geotechnical and foundation engineering models especially since the success of each project relies on numerous amounts of data. In this study, two applications of AI in the field of geotechnical and foundation engineering are presented - spatial interpolation of standard penetration test (SPT) data and prediction of consolidation of clay. SPT and soil profile data may be predicted and estimated at any location and depth at a site that has no available borehole test data using artificial intelligence techniques such as artificial neural networks (ANN) based on available geospatial information from nearby boreholes. ANN can also be used to accelerate the calculation of various theoretical methods such as the one-dimensional consolidation theory of clay with high efficiency by using lesser computation resources. The results of the study showed that ANN can be a valuable, powerful, and practical tool in providing various information that is needed in geotechnical and foundation design.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1994년도 가을 학술발표회 논문집
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• pp.175-181
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• 1994

In order to accelerate the rate of consolidation settlement and to gain a required shear strength for a given soft clay deposit, the preloading technique combined with a vertical drainage system has been widely applied. In this study, the theory of axisymmetric concolidation, which considers the variation of compressibility and permeability during the consolidation process, has been developed. Smear and well resistance effects are also considered. Furthermore, several back-analysis schemes such as simplex method, BFGS method, and ADS have been adopted in the axisymmetric consolidation program(AXICON). The measured data in the first stage of consolidation are utilized to predict the subsequent consolidation behavior.