• 한국지반공학회논문집
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• 제28권11호
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• pp.41-52
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• 2012

석션드레인공법은 연직배수재를 통해 연약지반에 직접 진공압을 가하게 되므로 진공압에 의해 배수재 주변의 경화영역이 형성된다. 이러한 경화영역은 지반의 투수성을 저하시켜 간극수 배출 효율이 급격히 저하된다. 본 연구에서는 배수효율을 저하시키는 요인 중 하나인 경화영역을 최소화하기 위해 단계 진공압을 고려하였다. 단계 진공압(-20kPa, -40kPa, -60kPa, -80kPa) 적용 기간이 경화영역과 지반개량 효과에 미치는 영향을 평가하기 위해 부산 해성 점토를 대상으로 단계별로 진공압 적용일자를 달리하여 실내시험을 수행하였다. 강도(CPT) 및 함수비 시험과 이론적 검증을 통해 경화영역의 범위는 약 7.0cm 이내이고, 경화영역 내에서의 투수계수 저하비는 약 2.0~4.0으로 평가되었다. 또한, 일괄적인 진공재하방식보다는 단계재하방식이 최종침하량 측면에서 더 우수한 것으로 나타났으며, 단계별 진공압의 적용기간도 대상 점토의 특성을 고려하여 결정되어야 함을 보였다. 수치해석 결과 경화영역을 고려하는 것이 실측값에 유사한 결과를 도출할 수 있음을 확인하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1991년도 추계학술발표회 논문집 지반공학에서의 컴퓨터 활용 COMPUTER UTILIZATION IN GEOTECHNICAL ENGINEERING
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• pp.362-375
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• 1991

Background and Necessity of the study : For more than 20 years, the soil engineering reserach group of Chonnam National University has been performing the deformation analysis of soft clayey foundation, since the University is located near the south-western coast of Korean Peninsulla, along which tide reclamation works have been under proaressing. Associsted with the fact mentioned above, the researchers have been developing a computer program in order to carry out deformation analysis of soft foundation since early 1980. Case-studies : In this research, the Biot's equation was selected as the governing equation coupled with several constitutive models including original and modified Cam-clay models, elasto-viscoplastic model, Lade's model etc. The anisotropy of soi1 can be considered in this program. To validate the accuracy of the computer program developed a couple of case-studies were performed. These include the pilot banking, sand drain considering smear effect and compound foundation reinforced with sheet pile into soft foundation.i) The pilot banking Good results could be acquired by assuming banking load as the body force composed of finite element mesh rather than equivalent concentrated load.ii) The sand drain Due to smear, the delay of consolidation was remarkable at the early stsge. so safety for the failure of foundation should be checked for the initial step of consolidation. iii) The compound foundation Accurate results were obtained by introducing the joint element method for the soft foundation reinforced with sheet pile into soiㅣ.

• 산업기술연구
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• 제20권A호
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• pp.101-111
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• 2000

This research is results of experimental and numerical works on characteristic of strength increase and bearing capacity in dredged and reclaimed soil due to desiccation shrinkage. For a soil sampled from southern coastal area in Korea, basic soil property tests and standard consolidation test with falling head permeability tests were carried out to obtain consolidational characteristics of soil. Double cone penetration test, laboratory vane test and unconfined compression test were also performed to investigate the change of shear strength with degree of desiccation. Model tests were performed in 1G environment and 30G level artificially accelerated condition by using the centrifuge model test facilities to investigate the bearing capacity of desiccated ground. Test results were analyzed by using the theoretical and load-settlement characteristics method proposed by Meyehof & Hanna(1978). On the other hands, the numerical technique, using the finite strain consolidation theory considering the effect of desiccation was used to estimate the appropriate time of using heavy construction equipments in field with respect to strength increase due to desiccation.

• KDI Journal of Economic Policy
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• 제25권1호
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• pp.55-98
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• 2003

본 연구는 국내 은행산업의 대형화 및 시장집중도 상승에 따른 은행서비스 시장의 경쟁저하 및 독과점화 우려에 대해 실증적인 분석을 시도한 것이다. 실증분석은 1996년 1월부터 2002년 12월까지 84개월 동안의 은행산업 관련자료를 이용한 Bresnahan-Lau 방법, 즉 은행서비스에 대한 수요함수와 공급함수를 추정하는 방법으로 진행되었다. 추정결과는 전체 표본기간 동안에는 국내 은행산업이 완전경쟁 수준의 가격설정행태(pricing behavior)를 보였으며, 시장집중도 상승을 고려하여 표본기간을 구분할 경우 구분시점에 따라 다소 차이는 있으나, 일반적인 우려와는 달리 시장집중도가 상승한 이후에 적어도 현재까지는 경쟁이 저하되지는 않았다는 것을 시사하고 있다.

• 한국농촌건축학회논문집
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• 제13권4호
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• pp.115-124
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• 2011

This study examines the process of urban formation in the city of Yanji. The analysis is done by the change of street pattern and major facility location in a timely manner by appling space syntax method. This research categorizes the pattern of the urban growth focused on two urban forms, street and major buildings, in the city and is offered of the meaning of the first value on interpretation of the urban growth in the city of Yanji. The result of the research are as follows. First, the period of the city transformation is divided into four stage; intuitive period, grid-iron formative period, consolidation period, and urban expansion period. Second, characteristics of each stage have been analyzed. At the first stage, the city started to frame along both buildings and streets which were placed without a plan. At the second stage, the city was planned and constructed into new grid-iron pattern ignoring existing context by Jananese colony. At the consolidation period, the road system expands from the city center toward suburban. At the last expansion period, the shape of the city has complicated its shape with complex road system. This study contributes to provide a basic analysis and data to investigate how the Yanji city has evolved over period of time. But further continuous research should be done for future urban development of the Yanji city.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1039-1046
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• 2005

After clay particles have been sediment isotropically, the clay deposits have been consolidated under $K_0$-stress system. Therefore, in order to predict the behavior in-situ of normally consolidated clays, the laboratory test should be enforced under $K_0$-stress system and should obtain the characteristics of normally consolidated clays. And relationship of stress-strain on clay is effected on not only method of consolidation but also characteristic of visco-plastic behavior. Saturated clay is effected more this trend. So, rate of strain is considered to understand exact stress-strain relationship. In this study, the series of undrained triaxial compression tests were preformed on remolded specimens which was made by slurry of clay, consolidated under $K_0$-stress systems. And the undrained triaxial compression test were preformed to examine behavior of stress-strain relationship due to rate of shear strain relationship due to rate of shear strain.

• KSBB Journal
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• 제32권3호
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• pp.206-211
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• 2017

The physical method used to prevent a landslide has the risk of environmental pollution. Calcite forming bacteria (CFB) have been received increasing attention as a novel and environmental friendly strategy for the soil improvement. In this study, we selected 11 CFB strains with high calcite production. We also examined survivability and calcite productivity of the strains under various stress conditions to select strains with high resistance to various stresses. Two strains was selected by environment stress. Sphingobacterium sp. KJ-32 and Viridibacillus arenosi B-25 precipitate calcite more than other strains at pH 5 and $15^{\circ}C$ respectively. Bio-consolidated soil cakes were made using various calcium salts (calcium chloride, calcium acetate, calcium lactate, calcium gluconate) with mixed culture of 2 strains. Among them, the calcite made using calcium chloride was the largest. These observations demonstrate that this bio-consolidation technology has the potential for eco-friendly prevention of landslide and soil improvement.

• Geomechanics and Engineering
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• 제8권5호
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• pp.707-726
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• 2015

This paper investigates the time dependent behaviour of Haarajoki test embankment on soft structured clay deposit. Half of the embankment is constructed on an area improved with prefabricated vertical drains, while the other half is constructed on the natural deposit without any ground improvement. To analyse the PVD-improved subsoil, axisymmetric vertical drains were converted into equivalent plane strain conditions using three different approaches. The construction and consolidation of the embankment are analysed with the finite element method using a recently developed anisotropic model for time-dependent behaviour of soft clays. The constitutive model, namely ACM-S accounts for combined effects of plastic anisotropy, interparticle bonding and degradation of bonds and creep. For comparison, the problem is also analysed with isotropic Soft Soil Creep and Modified Cam Clay models. The results of the numerical analyses are compared with the field measurements. The results show that neglecting effects of anisotropy, destructuration and creep may lead to inaccurate predictions of soft clay response. Additionally, the numerical results show that the matching methods accurately predict the consolidation behaviour of the embankment on PVD improved soft clays and provide a useful tool for engineering practice.

• Ocean and Polar Research
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• 제25권spc3호
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• pp.385-392
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• 2003

A new type of soft ground breakwater was recently developed, which does not need ground improvement because of light weight and structural characteristics. The various studies about consolidation settlements and lateral behavior of proposed soft ground breakwater have been conducted. But, the systematic investigations on the construction performance and long-term settlements of new type breakwater has not been accomplished. In this study, construction simulation of soft ground breakwater with soil box model test and experiments of the long-term wave loaded breakwater were performed. The results of test shows that it is possible to compensate differential settlements by dead loading and/or suction pressure, and to reduce the consolidation settlements by preloading method. It was also found that the vertical and lateral displacements of long-term wave loaded breakwater were negligible.

• 한국지반공학회논문집
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• 제17권4호
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• pp.209-220
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• 2001

준설매립지반 표층강도증진을 위한 수평진공배수공법 적용시의 압밀현상 예측을 위한 연구를 수행하였다. 초연약지반에 수평배수재와 진공압을 이용하여 수평진공배수 공법을 적용할 경우, 배수재 부근에서 3차원적 배수특성과 넓은 범위의 유효응력의 변화, 지반의 압축성 및 투수성이 크게 변화하게 된다. 이를 위하여 3차원 배수특성과 다양한 경계조건, 부의 간극수압 발생을 통한 유효응력의 증가, 유효응력에 따른 압축성과 투수성의 비선형성을 포함할 수 있도록 기존의 3차원 압밀 지배방정식을 확장 유도하였고, 유효응력-간극비-투수계수의 관계를 누승형태의 함수로 표현하여 사용하였다. 해석기법의 타당성을 검증하기 위하여 실내에서 수행된 대형 토조실험 결과를 모델링하여 좋은 일치를 확인하였고, 이를 바탕으로 수평진공배수공법 적용시의 압밀효과에 대한 분석결과 드레인이 타설된 상부지반에서는 균등한 개량효과의 결과를, 하부의 미개량 지반에서는 자중압밀에 의한 압밀효과를 확인할 수 있었으며 배수재의 수평타설 간격에 따른 압밀효과 분석을 통하여 적정 배수재 설치간격의 범위를 확인하였다.