• 한국농공학회논문집
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• 제47권2호
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• pp.87-96
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• 2005

In this research, an attempt is made to derive the practical estimation of the degree of consolidation in soft clay from field measurements under embankments. For the practical estimation of pore water pressure in soft clay, the elasto-viscous rheological model was proposed, with a transform of parameters and a field geotechnical measurements in southern Korea. By using the rheological properties of soft clays and the dissipation of excess pore water pressure behaviour during step loading, a degree of consolidation or pore water pressure estimation in the future can be performed, and are shown to be generally close to the field measurements of pore water pressure. Finally, a pore water pressure behaviour in soft clay can be explained through measured data in field and the excess pore water pressure data can also be used to estimate settlement.

• 한국지반공학회논문집
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• 제21권4호
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• pp.83-98
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• 2005

본 연구에서는 포화 점성토지반 침하량의 합리적인 평가를 위한 새로운 개념의 응력경로법 적용방법을 제안하였다. 제안된 적용방법은 특정 점성토지반에 대해 구조물 침하와 관련하여 현장에서 나타날 수 있는 모든 응력변화 조건을 포괄하는 특성변형거동을 실험적으로 선행하여 평가한 다음, 이를 이용하여 일체의 추가적인 시험없이 발생가능한 다양한 현장조건에 대해 손쉽게 침하량을 평가하는 방법이다. 본 연구의 Part I에서는 이러한 새로운 침하량 평가개념의 실용화와 관련하여 포화 점성토지반의 침하관련 특성변형거동을 최소한의 시험만으로 효율적으로 평가하고 이를 바탕으로 임의의 응력변화 조건에 대해 손쉽게 변형거동을 예측하는 구체적인 방법을 개발하였으며, 그 적용성을 실제 사례를 통해 명확히 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제34권6호
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• pp.914-921
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• 2010

연약지반에 구조물을 시공시 지반의 지지력 약화에 의해 지반침하가 발생한다. 이를 방지하기 위하여 연약지반의 개량이 요구될 뿐만아니라 합리적인 시공관리를 위하여 침하량 예측이 선행되어야 한다. 본 연구에서는 구조물 설계 및 시공 초기단계에서 지반의 침하량을 예측하기 위해 인공신경망을 이용하였다. 인공신경망을 이용하여 대상지역의 원지반에서 발생하는 침하량과 D.C.M공법을 적용하여 개량된 지반에서 발생하는 침하량을 예측하고, 대상지역의 침하거동 및 침하량을 Mohr-Coulomb모델을 이용한 연속체 해석 결과와 인공신경망을 수행한 결과를 비교하였다. 그 예측결과 D.C.M이 적용된 지반이 원지반보다 0.8배 감소한 침하량을 보였다. 연속체 해석과 인공신경망을 이용해 도출된 결과는 결정계수 0.79로 비교적 높은 상관관계를 보였다. 따라서 본 연구는 연약지반 개량공법의 침하량 예측이 실내실험자료를 통해 평가하는 것이 가능하다는 것을 확인하였다.

• 한국지반환경공학회 논문집
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• 제5권3호
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• pp.17-30
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• 2004

본 연구에서는 현장타설말뚝의 지지력에 관한 기존 및 IGM 이론의 적용성을 비교 평가하고, 변위를 고려한 지지력의 결정을 위해 IGM 상단부에서의 기준침하량 결정식을 제안하였다. 제안식은 말뚝의 두부침하량, IGM 상부 토층의 하중전이특성 및 말뚝의 탄성압축 이론에 기초하였다. 특히, 기존 및 IGM 이론의 적용성과 제안식의 적용성을 검증하기 위해 국내외 재하시험 결과를 이용한 분석이 실시되었다. 재하시험 결과를 이용하여 분석한 결과 제안식이 활용된 IGM 이론에 의해 향후 말뚝 설계시 변위를 고려한 지지력의 해석이 가능할 것으로 판단되었다. 특히, 제안식에 도입된 침하보정계수 $k_m$은 지반상태나 하중전이 특성을 반영하는 계수로서 하중 및 변형 증가에 따라 변화하는 특징을 보였다.

• Geomechanics and Engineering
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• 제5권4호
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• pp.363-377
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• 2013

Any structure constructed on the earth is supported by the underlying soil. Foundation is an interfacing element between superstructure and the underlying soil that transmits the loads supported by the foundation including its self weight. Foundation design requires evaluation of safe bearing capacity along with both immediate and long term settlements. Weak and compressible soils are subjected to problems related to bearing capacity and settlement. The conventional method of design of footing requires sufficient safety against failure and the settlement must be kept within the allowable limit. These requirements are dependent on the bearing capacity of soil. Thus, the estimation of load carrying capacity of footing is the most important step in the design of foundation. A number of theoretical approaches, in-situ tests and laboratory model tests are available to find out the bearing capacity of footings. The reliability of any theory can be demonstrated by comparing it with the experimental results. Results from laboratory model tests on square footings resting on sand are presented in this paper. The variation of bearing capacity of sand below a model plate footing of square shape with variation in size, depth and the effect of permissible settlement are evaluated. A steel tank of size $900mm{\times}1200mm{\times}1000mm$ is used for conducting model tests. Bearing capacity factor $N_{\gamma}$ is evaluated and is compared with Terzaghi, Meyerhof, Hansen and Vesic's $N_{\gamma}$ values. From the experimental investigations it is found that, as the depth of sand cushion below the footing ($D_{sc}$) increases, ultimate bearing capacity and settlement values show an increasing trend up to a certain depth of sand cushion.

• 한국지반공학회논문집
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• 제18권2호
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• pp.107-121
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• 2002

본 연구의 주된 목적은 지리정보체계(GIS, Geographic Information System) 기법을 활용하여 대규모매립지반의 장기적인 침하관리를 보다 효율적으로 수행할 수 있는 새로운 접근방법을 제시함에 있으며, 또한 제시된 GIS 기법 등을 활용하여 선행재하공법이 적용된 인턴국제공항 부지 전체연약층의 향후 예상침하량을 추정하여 보았다. 이 과정에서 공사 중 및 현재까지 측정된 다양한 침하량 계측자료가 분석되었으며, 아울러 Nagaraj 등의 이론을 토대로 한 재압축 지수의 산정과 Mesri & Godlewski가 제시한 과압밀상태에서의 2차압밀계수재압축지수 사이의 비를 정의하는 관계식 등을 토대로 2차압밀계수의 결정이 이루어 졌다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회 2차
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• pp.76-80
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• 2010

This paper describes that estimation methods for the distribution of consolidation settlements to investigate the influence of distribution characteristics of compression index on the spatial distribution of consolidation settlements. When the variation of compression index is considerable, the spatial distribution of compression index is estimated using ordinary cokriging. The spatial distribution of consolidation settlements estimated by considering both the variation of compression index and void ratio (CASE-1) is different from the conventional mean value of all soil properties (CASE-2). The settlement of CASE-1 shows the larger variation at short distances rather than that of CASE-2. Whereas the spatial settlement distribution of CASE-1 is affected by the spatial distribution of compression index and the thickness of consolidation layer, the distribution of CASE-2 is significantly influenced by the distribution of the thickness of consolidation layer.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 기초기술학술발표회
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• pp.11-29
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• 2002

Current design of pile group is based on the estimation of the overall bearing capacity of a pile group from that of a single pile using a group efficiency. However, the behaviors of a pile group are influenced by various factors such as method of pile installation, pile-soil-pile interaction, cap-soil-pile interaction, etc. Thus it is practically impossible to take into account these factors reasonably with the only group efficiency, In this paper, a new method for the design of pile groups is proposed, where the significant factors affecting the behavior of a pile group are considered separately by adopting several efficiencies. Furthermore, in the proposed method, the load transfer characteristics of piles and the difference of pile behaviors with respect to the pile locations in group can be taken into account. The efficiencies for the method are determined using the settlement failure criterion, which is consistent with the concept of allowable settlement for structures. The efficiencies calculated from the results of existing model tests are presented, and the bearing capacity of a pile group in the other model test is calculated and compared with that from the test result, to verify the validity of the proposed method.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.170-180
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• 2008

Successful design, construction and maintenance of NATM tunnel demands prediction, control, stability guidelines, the estimation pre-improvement support system and monitoring of surface settlement, gradient and ground displacement with high accuracy. Moreover, urban NATM tunnel under difficult geotechnical conditions is important the estimation and necessary of pre-improvement support system. Various strategies have been proposed for the quantitative estimation of pre-improvement support system. This paper was investigated and analysed an assessment technique for the quantitative estimation of pre-improvement support system on underground space, as mountain and urban tunnel, in detail. The analysis performed on design and construction stage with field database using the proposed stability estimation index by many researcher including the critical strain and the apparent Young's modulus concept.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.395-403
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• 2007

Railroad track consists of relatively simple structures such as rail, sleeper, ballast. Roadbed shares vertical pressure by train load which passed through rail to ballast as base that supports the track. For evaluating stress and displacement of roadbed due to the railroad load is an important role on the track as a basic data for estimation of the durability and design of the roadbed thickness. GEOTRACK program applied multi-layered theory was developed for analyzing railroad track structure. GEOTRACK program is a sort of numerical analysis program which has advantage that can analysis component of track by simple method. In this study, this program was used to preform the numerical analysis by changing track conditions and roadbed conditions such as tie, reinforced roadbed, dynamic wheel load, Resilient modulus and so on. Further detail will be presented on the paper.