• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.223-230
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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 in-situ tests were carried out to utilize gravel as a substitute for sand. 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, The clogging effect was checked at various depth in gravel column after the test. 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.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.119-122
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• 2009

The gravel compaction pile method has been used as a soft foundation improvement method because bearing capacity and discharge capacity is excellent. But the discharge capacity decreased when the clogging was generated because the clay penetrate into a void of gravel compaction pile. Accordingly, the purpose of this study is to reduce the clogging generation in gravel compaction pile constructing in the soft ground and take a step to minimize a void of gravel compaction pile. And the proper mixing ratio was determined with the large scale direct shear test performed to get strength and permeability with mixing ratio of crushed stone and sand(100:0, 90:10, 85:15, 80:20, 75:25). As a result of the test, it was showed that internal friction angle was the highest at 85:15 mixing ratio of crushed stone and sand and we can make sure a tendency of internal friction angle's decrease when the mixing ratio of crushed stone and sand passed 15%.

• 한국지반공학회논문집
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• 제33권6호
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• pp.27-36
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• 2017

자갈다짐말뚝(Gravel Compaction Pile) 공법은 연약지반 개량공법 중의 하나로 육상 및 해상에서 연약 지반을 개량하기 위해 많이 사용되어 왔다. 자갈다짐말뚝으로 보강된 지반의 극한 지지력은 자갈다짐말뚝 및 지반의 강도, 치환율, 시공조건 등에 영향을 받으며 이를 예측하기 위한 다양한 예측식이 제안되었다. 하지만 기존 예측식을 활용한 극한지지력 예측은 오차율 및 변동성이 매우 크며, 실제 설계에 활용하기에는 부적합한 것으로 나타났다. 본 연구에서는 자갈다짐말뚝으로 보강된 지반의 극한 지지력을 예측하기 위하여 현장 재하시험결과를 활용한 다중회귀분석을 수행하였으며, 단일잔류 교차검증에 따른 예측오차평가를 통하여 가장 효율적인 입력변수를 선정하고 이에 대한 극한 지지력 예측식을 제안하였다. 또한 선정된 입력변수를 활용하여 인공신경망 적용에 따른 극한 지지력 예측오차를 평가하고 이를 기존 예측식에 따른 결과와 비교 분석하였다.

• 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.

• 한국지반공학회논문집
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• 제20권8호
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• pp.41-48
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• 2004

이 연구에서는 아직 국내에서는 시공실적이 없는 쇄석다짐말뚝(Gravel Compaction pile)공법의 적용성을 판단하기 위하여 SCP와 GCP의 모형토조시험을 수행하였다. 즉, 원통형 압밀상자(지름 20cm, 높이 40cm)에 치환율 30, 40, 50, 60, 70%로 달리 조성하여 원심력 압밀시험기를 이용하여 압밀시킨 후, 재하시험을 통하여 두 공법의 지지력 특성을 비교 검토하였다. 또한 모형시험을 통해 얻어진 극한지지력을 기존에 제안된 SCP 및 GCP 시공지반의 극한지지력 산정식을 이용한 계산값과 비교하였다. 모형시험 결과 GCP 시공지반이 SCP 시공지반에 비해 지지력 측면에서 더 우수한 것으로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.443-452
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• 2005

The compaction pile methods with low replacement area ratio used sand(SCP) or gravel(GCP) has been usually applied to improvement of soft clay deposits. In order to design accurately compaction pile method with low replacement area ratio, it is important to understand the mechanical interaction between sand piles and clays and its mechanism during consolidation process of the composition ground. In this paper, a series of numerical analyses on composition ground improved by SCP and GCP with low replacement area ratio were carried out, in order to investigate the mechanical interaction between sand piles and clays. The applicability of numerical analyses, in which and elasto-viscoplastic consolidation finite element method was applied, could be confirmed comparing with results of a series of model tests on consolidation behaviors of composition ground improved by SCP. And,through the results of the numerical analyses, each mechanical behaviors of compaction piles and clays in the composition ground during consolidation was elucidated, together with stress sharing mechanism between compaction piles and clays.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 춘계학술대회 논문집
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• pp.289-294
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• 2002

Sand Compaction Pile (SCP) method, which uses sand material, is frequently used in Korea. However, the use of sand for SCP faces environmental and economical problems with the shortage of its resources. Therefore, it is necessary to substitute other materials for compaction piles. One of the alternatives is using gravel in lieu of sand. Granular Pile, constituted with sand and crushed-stone, is one of the methods to improve soft clay and loose sandy ground. In this study, modeled pile load tests are performed in test cell. The observations are made on the consolidation and the variation of water table of three different grounds, original, sand pile installed, and granular pile installed ground. In addition, engineering characteristics such as bearing capacity, settlement and drainage are investigated. The test results show that Gravel Compaction Pile (GCP) is more efficient for increasing bearing capacity and reducing settlement than SCP and had similar pore water pressure dissipation to sand. Therefore, the results show that GCP can be a good substitution for SCP.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 추계학술대회 논문집
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• pp.407-414
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• 1999

Sand drain as a vertical drainage is widely used in soft ground improvement. Recently, sand, the principal source of sand drain, is running out. A laboratory model test was 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. According to the test, the settlement was found to be smaller in gravel drain than in sand drain. The increase in bearing capacity by gravel rile explains the result. The clogging effect was not found in gravel column. As a result, it is assumed that gravel is relatively acceptable as a drainage material. Gravel material seems better than sand material in bearing capacity and it is found that bearing capacity is larger when gravel is used as compaction pile than as drain from in-situ test on bearing capacity. Increase of bearing capacity with gravel pile means an effect of composite ground by stiffness of gravel material. It can lie supposed to use gravel pile instead of sand pile in view of consolidation effect and bearing capacity.

• 한국지반공학회논문집
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• 제34권6호
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• pp.37-47
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• 2018

본 연구에서는 모래다짐말뚝(sand compaction pile, SCP)과 자갈다짐말뚝(gravel compaction pile, GCP)으로 보강된 지반의 극한지지력을 예측할 수 있는 식을 제안하고자 34개의 국내외 실내재하시험 데이터를 수집하고 이를 분석하였다. 수집된 자료를 기존의 이론식에 의한 극한지지력 산정 값과 비교하여 기존 이론식의 예측 정도를 파악하였다. 또한 극한 지지력 예측식을 제안하고자 다중회귀분석을 수행하였으며, 단일잔류 교차검증에 따른 예측오차평가를 통하여 가장 효율적인 입력변수의 수 및 조합을 선정하였다. 최종적으로 SCP와 GCP의 실내재하시험에 대한 극한 지지력을 예측하기 위한 다중회귀식을 제안하였으며 그 성능을 평가하였다.

• 한국산학기술학회논문지
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• 제14권2호
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• pp.936-942
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• 2013

이 연구에서는 그동안 많은 연구가 이루어지지 않은 저치환율 SCP(sand compaction pile) 및 GCP(gravel compaction pile) 공법의 거동특성을 비교하기 위해 1g 모형시험을 수행하였다. 모형시험은 단위셀(unit cell) 개념을 적용하기 위해 단일말뚝 복합지반을 저치환율($a_s$=10%, 20%, 30%) 조건으로 조성하여 수행하였다. 모형시험결과 연약지반 개량을 위해서 SCP의 대체공법으로 GCP공법을 적용할 경우에 지반개량으로 인해서 발생하는 지지력 증가효과와 침하저감효과 및 압밀촉진효과는 SCP공법을 적용한 경우에 비해서 다소 우수한 것으로 나타났다.