• 한국지반공학회논문집
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• 제38권7호
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• pp.25-37
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• 2022

본 논문에서는 연약지반개량을 위해 활용되고 있는 모래다짐말뚝 공법의 개선을 위해 개발된 입도조정골재 다짐말뚝의 구근 형성 및 품질을 평가하고자 다짐말뚝 시공을 모사하는 축소모형실험 시스템을 개발하고 일련의 실험을 수행하였다. 현재 모래다짐말뚝 공법의 경우 모래의 공급 부족으로 인해 경제성이 하락하였고, 쇄석다짐말뚝 공법은 해상 초연약점토지반에 시공 시 구근의 팽창 파괴로 인한 불균일한 구근과 퍼짐 현상 발생으로 해상 연약지반 적용에 한계가 있어왔다. 구근의 균일한 형성은 다짐말뚝의 지지력에 큰 영향을 미치나, 현재까지 구근 형성에 대한 연구사례는 전무하다. 따라서, 본 연구에서는 다짐말뚝 구근이 시공되는 절차를 모사하여 구근 형성 메커니즘을 규명하고, 기존 다짐말뚝 공법을 개선하는 입도조정골재의 품질 평가를 목표로 하였다. 본 연구에서는 다짐말뚝 재료와 지반 강도를 매개변수로 하여 4차례 실험을 수행하였다. 다짐말뚝 재료는 입도조정골재와 모래를 비교·분석하였다. 실험결과, 입도조정골재 다짐말뚝의 구근은 모래다짐말뚝과 유사한 품질로 나타났으며, 입도조정골재 다짐말뚝의 지지력이 모래다짐말뚝 보다 향상되는 것을 확인하였다.

• 한국지열·수열에너지학회논문집
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• 제18권2호
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• pp.1-9
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• 2022

A novel steel-pipe energy pile is introduced, in which the deformed rebars for main reinforcing are replaced with steel pipes in a large diameter cast-in-place energy pile. Here, the steel pipes act as not only reinforcements but also heat exchangers by circulating the working fluid through the hollow hole in the steel pipes. Under this concept, the steel-pipe energy pile can serve a role of supporting main structures and exchanging heat with surrounding mediums without installing additional heat exchange pipes. In this study, the steel-pipe energy pile was constructed in a test bed considering the material properties of steel pipes and the subsoil investigation. Then, the thermal performance test (TPT) in cooling condition was conducted in the constructed energy pile to investigate thermal performance. In addition, the thermal performance of the steel-pipe energy pile was compared with that of the conventional large diameter cast-in-place energy pile to evaluate its applicability. As a result, the steel-pipe energy pile showed 11% higher thermal performance than the conventional energy pile along with much simpler construction processes.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 2부
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• pp.63-66
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• 2011

The aim of this study is to estimate the field applicability of PBFM to replace in-site soil with pile backfill used to replace the existing cement paste. As results, the flowability, segregation and bleeding, and bond strength of PBFM was a good performance than that of the existing cement paste. But the skin friction of pile by Pile Driving Analyzer (PDA) and compressive strength was slightly decreased than that of the existing cement paste. However, as pile backfill materials, and in terms of economics and environment, the applicability of PBFM is considered very effective.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.207-214
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• 2000

Sand Compaction Pile method is one of the widely used ground improvement techniques at loose sand or soft clay ground in Asian countries. However, due to environmental and economical problems concerning shortage of sand resources alternative materials are needed to substitute sand for SCP. This study is on the applicability of slag as an alternative material SCP. Consolidation and direct shear test are performed for the slag-clay composite specimens to find out the positive effects of consolidation rate and shear resistance of slag reinforced ground. The result shows that slag has similar effects with sand in consolidation and shear resistance behavior in composite ground, which says slag can be used as alternative material of sand for SCP.

• 한국세라믹학회지
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• 제47권5호
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• pp.419-425
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• 2010

In order to examine the P.H.C pile raw material using glass forming ceramic. The used materials is ordinary portland cement, waste TFT-LCD glass powder and reactive agent(Ca$(OH)_2$). The first experiment is characteristics analysis of the waste TFT-LCD glass powder, For the second experiment is mortar and concrete compressive strength for using of the concrete file raw material for waste TFT-LCD glass powder. The results of experiment showed that the substitution ratio of 10% waste TFT-LCD glass powder and 1% reactive agent(Ca$(OH)_2$) was excellent at a point of view for the physical characteristic. The study's most important finding is that the recycling of waste TFT-LCD glass powder.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 연약지반처리위원회 학술세미나
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• pp.32-41
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• 2000

Sand drain as a vertical drainage is widely used in soft ground improvement Recently, sand, the principal source of sand drain, is running out. The laboratory model tests were carried out to utilize gravel as a substitute for sand. Though which the characteristics of gravel are compared to those of sand for engineering purpose. Two cylindrical containers for the model test were filled with marine clayey soil from the west coast of Korea with a column in the center, one with sand, the other with gravel. Vibrating wire type piezometers were installed at the distance of 1.0D, 1.5D and 2.0D from the center of the column. The characteristics of consolidation were studied with data obtained from the measuring instrument place on the surface of the container. The parameter study was performed on the marine clayey soil before and after the test in order to verify the effectiveness of the improvement. The clogging effect was checked at various depth in gravel column after the test. In-situ tests area was divided into two areas by material used. One is Sand Drain(SD) and Sand Compaction Pile(SCP) area, the other is Gravel Drain(GD) and Gravel Compaction Pile(GCP) area. Both areas were monitored to obtain the information on settlement, pore water pressure and bearing capacity by measuring instruments for stage loading caused by embankment. The results of measurements were analyzed. According to the test results, the settlement was found to be smaller in gravel drain than in sand drain. The increase in bearing capacity by gravel pile explains the result. The clogging effect was not found in gravel column. It is assumed that gravel is relatively acceptable as a drainage material. Gravel is considered to be a better material than sand for bearing capacity, and it is found that bearing capacity is larger when gravel is used as a gravel compaction pile than as a gravel drain.

• Structural Engineering and Mechanics
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• 제46권1호
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• pp.53-73
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• 2013

Prediction of prestressed concrete girder integral abutment bridge (IAB) load effect requires understanding of the inherent uncertainties as it relates to thermal loading, time-dependent effects, bridge material properties and soil properties. In addition, complex inelastic and hysteretic behavior must be considered over an extended, 75-year bridge life. The present study establishes IAB displacement and internal force statistics based on available material property and soil property statistical models and Monte Carlo simulations. Numerical models within the simulation were developed to evaluate the 75-year bridge displacements and internal forces based on 2D numerical models that were calibrated against four field monitored IABs. The considered input uncertainties include both resistance and load variables. Material variables are: (1) concrete elastic modulus; (2) backfill stiffness; and (3) lateral pile soil stiffness. Thermal, time dependent, and soil loading variables are: (1) superstructure temperature fluctuation; (2) superstructure concrete thermal expansion coefficient; (3) superstructure temperature gradient; (4) concrete creep and shrinkage; (5) bridge construction timeline; and (6) backfill pressure on backwall and abutment. IAB displacement and internal force statistics were established for: (1) bridge axial force; (2) bridge bending moment; (3) pile lateral force; (4) pile moment; (5) pile head/abutment displacement; (6) compressive stress at the top fiber at the mid-span of the exterior span; and (7) tensile stress at the bottom fiber at the mid-span of the exterior span. These established IAB displacement and internal force statistics provide a basis for future reliability-based design criteria development.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.404-411
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• 2009

The steel pipe of steel-concrete composite piles increases the pile strength and induces the ductile failure by constraining the deformation of the inner concrete. In this research, the load-movement relations and the reinforcement effect by the outer steel pipe in the steel-concrete composite pile were analyzed by performing three-dimensional numerical analyses, which can simulate the yielding behavior of the pile material and the elasto-plastic behavior of soils. The parameters analyzed in the study include three pile materials of steel, concrete and composite, pile diameter and loading direction. As the results, the axial capacity of the composite pile was 1.9 times larger than that of the steel pipe pile and similar with that of the concrete pile. At the allowable movement criteria, the horizontal capacity of the composite pile was 1.46 times larger than that of the steel pile and 1.25 times larger than that of the concrete pile. In addition, the horizontal movement at the pile head of the composite pile was about 78% of that of the steel pile and about 53% of that of the concrete pile, which showed that the movement reduction effect of the composite pile was significant and enables the economical design of drilled shafts.

• 전자공학회논문지
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• 제50권8호
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• pp.162-167
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• 2013

X-선과, ${\gamma}$-선을 이용한 형광분석장치는 현재 널리 쓰이는 물질의 고유특성을 분석하는 장치이다. 하지만 여러 가지 원인으로 인해 장치사용 시 측정 신호에서 중첩 현상이 발생한다. 검출 신호의 높이는 측정 물질의 특성을 반영하며 측정 물질을 정확히 분석하기 위해서는 중첩된 신호를 제거하거나 복원을 해야 한다. 현재 trapezoidal 필터는 형광분석장치에 널리 사용되고 있으며 중첩펄스 검출에서도 좋은 결과를 보이고 있다. 본 논문에서는 측정 신호의 사다리꼴 변형에 기반 한 중첩펄스 처리방법을 제안한다. 제안방법은 사다리꼴 필터를 이용한 최대값 검출 알고리즘에 두 개의 카운터와 몇 개의 레지스터만을 추가하여 추가적인 중첩펄스 처리 알고리즘을 구현하기 때문에 기존 방법에 비해 하드웨어 복잡도가 훨씬 적으면서도 정확히 중첩펄스를 처리 할 수 있다.

• 한국지반공학회논문집
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• 제21권9호
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• pp.87-102
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• 2005

기존의 구조물 또는 서비스에 근접한 터널굴착이 지상공간의 부족으로 인해 종종 도심지에서 이루어지며, 이러한 터널굴착으로 발생하는 지반변위가 인접한 구조물에 손상을 발생시킨다. 본 연구는 근거리 사진계측을 이용한 2차원 모형 파일-지반-터널굴착 실험에 초점을 두었다. 실험장비 및 절차와 더불어 마찰이 있는 사질토 지반으로 간주하는 알루미늄 봉의 특성에 대해서 소개하였다. 실험결과, VMS와 EngVis 프로그램을 이용한 포토 이미지 프로세스는 터널굴착으로 인한 파일 선단부의 거동을 측정하는데 유용한 도구임을 잘 보여 주었다. 결론적으로 사진계측기술을 이용한 실내모형실험을 통해 영향권과 관련된 파일 선단부의 거동 데이터를 생성할 수 있다. 본 연구는 사질토 지반에서 터널굴착으로 인한 정규화 된 파일 선단부의 침하를 근간으로 하는 영향권을 제시한다. 이러한 영향권은 실내모형실험과 수치해석을 통해 규명하였다. 모형실험으로부터 정규화 된 파일 선단부의 거동은 수치해석 결과와 잘 일치하였다. 본 논문에서 제시된 영향권은 계획단계에서 터널시공 위치를 선정하는데 유용할 것으로 판단되나, 지반조건을 고려하는 실제 상황에 적용끈기 위해서는 모형파일과 모형터널의 크기에 대한 축척을 실제크기와 맞게 조정해야 한다.