• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.1046-1050
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• 2010

During construction of a sea-crossing bridge grouting was used to fill densely the space between the bottom of caisson and the ground. This grout mixture was mixed with an anti-washout admixture after locating accurately the pre-cast caisson on three concrete landing pads. This method differs significantly from the costly conventional method, for bridge foundations offshore, where concrete is placed in situ after excavating inside of a temporary concrete coffering wall. To verify the grouting method in advance, the full-scale field tests were performed twice on land. After identifying the fluidity of the grout material to be filled, finding some possible problems with the main construction and revising the original design, the main construction has been continuing successfully with 20 caissons completed to date. The purpose of this paper is to introduce for the first time in Korea the grouting method including the automatic and the manual monitoring system based on the main construction of the caisson foundation.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.30-37
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• 2009

In doing the foundation work in the downtown, the popular complaints by means of Noise and vibration have been became heavy burden. Therefore, the noise & vibration-free screw PHC pile method will contribute to the foundation work by removal of the popular complaints and improvement of the constructability. In this paper, the load bearing capacity and displacement characteristics of the noise & vibration-free screw PHC pile were analyzed. The noise & vibration-free screw PHC pile's behavior was better well than the existing PHC pile's one.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.119-126
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• 2002

Fractures, especially faults have most significant influence on the difficulties encountered in various engineering and mining works, because they can give rise to inevitable reductions in shear strength as well as large increase in permeability. Thus, before underground access is possible, it is desirable to estimate the distribution and geometry of fractures in advance, if reliable structural data from e.g. Televiewer tool are available. To this end, fracture face mapping is just the evaluation method used to form a fracture image determined by intersecting of each fracture plane with a selected plane section of a rock mass, assuming that all fractures be planar with fixed-aperture. Although many fractures are geometrically complex and others are altered chemically, according to the abundant experiments in recent years, it would seem that the technique could be applied to benefit the design of numerous engineering works such as slope stability, tunnel excavations, dam foundation and diverse environmental works. This paper presents at first an evaluation algorithm for fracture face mapping and then concludes with various representative examples of applications.

• Geomechanics and Engineering
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• 제37권2호
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• pp.167-178
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• 2024

The natural frequency shift under cyclic environmental loads is a key issue in the design of monopile-based offshore wind power turbines because of their dynamic sensitivity. Existing evidence reveals that the natural frequency shift of the turbine system in sand is related to the varying foundation stiffness, which is caused by soil deformation around the monopile under cyclic loads. Therefore, it is an urgent need to investigate the effect of soil deformation on the system frequency. In the present paper, three generalized geometric models that can describe soil deformation under two-way cyclic loads are proposed. On this basis, the cycling-induced changes in soil parameters around the monopile are quantified. A theoretical approach considering three-spring foundation stiffness is employed to calculate the natural frequency during cycling. Further, a parametric study is conducted to describe and evaluate the frequency shift characteristics of the system under different conditions of sand relative density, pile slenderness ratio and pile-soil relative stiffness. The results indicate that the frequency shift trends are mainly affected by the pile-soil relative stiffness. Following the relevant conclusions, a design optimization is proposed to avoid resonance of the monopile-based wind turbines during their service life.

• 한국지반공학회지:지반
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• 제10권4호
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• pp.53-66
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• 1994

연약지반에 위치한 교대의 기초로서 말뚝기초를 채택할 경우 교대배면의 연약지반에는 측방유동같은 문제등이 빈번히 발생하고 있다. 지반이 측방유동을 일으킬 경우 기초말뚝은 전형적인 수동말뚝임에도 불구하고 교대기초말뚝의 설계시 수동말뚝으로 설계되지 않고 있다. 이러한 이유로는 측방유동의 정확한 판정이 어려운 점과 현재까지 합리적인 설계법이 확립되지 않은점 등을 들 수 있다. 본 연구에서는 측방이동이 발생된 우리나라의 몇몇 교대를 조사하였다. 이 조사에 의거하여 연약지반의 측방유동 판정 및 교대의 측방이동을 예측할 수 있는 판정기준을 제시하고자 한다. 본 연구결과 사면안전율이 말뚝효과를 고려할 결우 1.8이하, 말뚝효과를 무시한 경우 1.5이하에서는 교대측방이동이 발생할 수 있는 것으로 나타났다. 특히 사면안전율이 말뚝효과를 무시한 경우 1.0이하, 말뚝효과를 고려할 경우 1.1 이하에서는 과대한 교대측방이동이 발생하는 것으로 나타났다. 또한 교대의 허용측방이동량을 5cm라고 하면 사면의 소요안전율은 1.4(말뚝효과를 무시한 경우) 혹은 1.6(말뚝효과를 고려한 경우)이상이 되어야 한다.

• 한국지반공학회논문집
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• 제26권1호
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• pp.35-43
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• 2010

본 연구에서는 수치해석과 현장계측을 연계하여 압밀과 재하폭의 영향을 고려한 연약지반 상 팽이말뚝기초의 최적 침하량을 평가하여 기존의 침하량 산정법을 수정한산정 기법을 제안하였다. 팽이기초공법이 적용되는 연약지반(점성토, 사질토)을 선정하고, 3차원 유한요소해석을 통해 현재 팽이기초공법에서 고려치 못하는 압밀과 재하폭의 영향을 분석하였다. 분석 결과, $7\times7$ 이상의 팽이배열을 가지는 경우, 재하폭의 증가에 따라 영향깊이가 더 이상 증가하지 않는 것으로 나타났다. 이 때, 팽이말뚝 1개의 폭 BT(=0.5m)에서, 최대 영향깊이는 점성토지반의 경우에 28BT 정도를 보였으며, 사질토지반은 최대 $18B_T$로 나타났다. 본 연구 결과, 현재 재하폭과 압밀의 영향을 고려하지 못하는 팽이기초 침하량 산정식은 실제 계측 침하량과 비교하여 약 2배 이상 과다하게 산정하고 있음을 알 수 있었다. 이를 바탕으로 연약 단일지반에 따른 bilinear 형태의 영향깊이 산정식과 하중분산각을 제안하였고, 이를 통해 산정된 침하량은 실제 침하량과 비교적 유사하게 나타나 국내 현장조건을 적절히 반영할 수 있음을 확인할 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1993년도 지하공간 건설기술에 관한 서울 심포지움 논문집
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• pp.213-218
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• 1993

The paper deals with problems connected with heating and ventilation of underground premises for public use. Some properties of rock and special problems connected with designing ventilation systems for underground spaces are first briefly discussed. The rest of the paper deals with design of ventilation and heating systems. The conclusion is that there are no large problems with heating and ventiliation of underground premises, but there are still problems connected with for instance thermal properties of rock when water flows in the cracks. An optimum design demands better knowledge of these properties.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.379-386
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• 2001

Piled raft foundations are usually used to reduce total and differential settlements of superstructures. In the piled raft foundations, the raft is often on its own able to provide adequate bearing capacity and only few widely spaced piles are added to the foundation to keep settlements be1ow a certain limit. In this paper, experimental studies on the load sharing ratio between piles and raft are carried out. Also, for evaluating the application of optimum design technique using a genetic algorithm, optimal locations of files are compared with the results of laboratory model tests. from tile results of laboratory model tests, there are found that the load sharing ratio between files and raft is depended on the number of piles and stiffness of raft, and the optimal locations of piles became concentrated on the middle of rafts. From these results of laboratory model tests, the optimum technique using a genetic algorithm is acknowledged to the application in the piled raft.

• 한국재난정보학회 논문집
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• 제8권1호
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• pp.81-92
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• 2012

본 연구에서는 말뚝기초의 설계 및 시공과 관련하여 국내 103 개소 대형교량건설현장에 대한 실태를 조사 분석하였다. 그 결과, 지반조사 단계에서 지지층에 대한 심도확인과 조사위치 배치기준 적용이 미흡한 것으로 나타났다. 설계단계에서는 말뚝시험시공 없이 지지력을 산정하는 경우가 많았으며, 말뚝재하시험 시 재하용량 적용기준이 불명확하여 극한(또는 항복)지지력을 확인할 수 없었다. 재하시험을 수행하더라도 시험결과의 반영이 미흡하여 경제성을 검토하지 않는 등의 문제점이 나타났다. 말뚝기초 설계기준이 현장여건을 제대로 반영하지 못하여 과다설계가 될 경우 경제성을 기할 수 없다. 따라서, 말뚝기초의 지지력과 관련된 기존문헌을 고찰하고, 교량기초 설계 및 시공사례 분석을 통하여 시방서의 일부 내용을 개선하도록 제안하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1707-1711
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• 2008

Landing pier is connect from onshore to offshore with bridge type that a coast structure. The sub-structure is consisted of vertical or batter pile and combined reinforced concrete slab. These days useful design method of quay wall of landing pier type for pile foundation analysis abide by approximate depth of pile supported method, "Harbor and port design criterion, 2005 The ministry of land transport and maritime affairs". The approximate depth of pile supported is calculated two kind of method that one is assume to below depth of 1/$\beta$ from assumed submarine surface and other is 1st fixpoint depth by Chang(1937)'s theory. By this paper, FEM dynamic analysis of 3-dimensions was achieved that it has compared pile fixed end modeling with elastic spring modeling base on winkler theory.