• 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.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 말뚝기초 학술발표회
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• pp.107-141
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• 2000

Large diameter piles can be defined as piles with diameter of at least 0.76 m (2.5 ft). In bridge foundation, large diameter piles have been used as pier foundations and their use has been increased greatly. In this study, static pile load tests for large diameter piles peformed in Kwangan Grande Bridge construction site were introduced. Also, various sensor installation methods for several types of piles (that is, open-ended steel pipe pile, drilled shafts and socketed pipe piles), pipe axial load measuring method, load transfer analysis method and pile load test results (pile-head load - settlement curve, and pile axial load distribution curve along the pile depth) were introduced.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.70-77
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• 2010

In this paper, a case study of drivability and bearing capacity of large diameter steel pipe piles at PTT LNG site in Thailand is introduced. The LNG facilities were designed to be founded on steel pipe pile foundations driven into the weathered rock formation overlaid by sand layers. The drivability analyses of open ended pipe piles were carried out using GRL WEAP program and the bearing capacities of the piles were estimated. Dynamic load tests were performed to evaluate end bearing resistance, and it is shown that the measured end bearing resistance is smaller than the calculated end bearing because the plugging does not develop sufficiently in case of large diameter pipe piles.

• 한국해양공학회지
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• 제25권6호
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• pp.35-41
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• 2011

Recently, as large structures, which should support large design loads have been constructed, the study on the large diameter composite pile becomes necessary. The large diameter composite pile has the diameter over 700mm and consists of two parts of the upper steel pipe pile and the lower PHC pile by a mechanical joint. In this research, to analyze the bearing capacity and the material strength of the composite pile, three dimensional numerical analyses were performed. First, the numerical modeling method was verified by comparing the calculated load-movement curves of the pile with those of the field pile load tests. Then, a total of twelve analyses were performed by varying pile diameter and loading direction for three pile types of PHC, steel pipe and composite piles. The results showed that the vertical and the horizontal load-movement curves of the composite pile were identical with those of the steel pipe pile and the horizontal material strength of the composite pile was 60-80% larger than that of the PHC pile.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.277-284
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• 2000

Using the large diameter (D ＝ 2,500mm, L ＝ 40m) batter steel pipe piles, designed as compression piles but used as reaction piles during the static compression load test of socketed test piles (D ＝ 1,000mm, L ＝ 40m), static pile load tests for large diameter instrumented rock-socketed piles were performed. The reaction steel pipe piles were driven 20m into the marine deposit and weathered rock layer and then l0m socketed with reinforced concrete through the weathered rock layer and into hard rock layer. Steel pipe and concrete in the steel pile part, and concrete and rebars in the socketed parts were instrumented to measure strains in each part. The pullout amounts of reaction pile heads were also measured with LVDT. During the static pile load test, total compressional load of about 20MN was loaded on the head of test piles, but load above 20MN was not loaded due to lack of loading capacity of loading system. Over the course of the study, maximum pullout amount up to 7mm was measured in the heads of reaction piles when loaded op to 10MN and 1mm of pullout amount was measured. More than 85% of pullout load was transfered in the residual weathered rock layer and about 10% in the soft rock layer, which was somewhat different transfer mechanism in the static compressional load tests.

• 한국지반공학회논문집
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• 제18권1호
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• pp.5-16
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• 2002

본 연구에서는 직경 1,000mm의 시험말뚝에 대한 압축정재하시험 수행시 반력말뚝으로 사용된 직경 2,500mm의 대구경 경사반력소켓말뚝의 인발거동을 분석하였다. 경사반력말뚝은 풍화암층과 연암층 10m에 걸쳐서 현장타설말뚝으로 소켓되어졌으며, 강관부는 강관과 속채움콘크리트로, 그리고 소켓부는 콘크리트와 철근으로 구성되었다. 각 구성부재에 작용하는 변형율을 측정하기 위해 센서를 설치하였으며, 반력말뚝두부의 인발량을 측정하기 위하여 LVDT를 설치하였다. 정재하시험중 재하된 최대인발하중은 10MN이었으며 최대인발변위는 7m, 잔류인발변위는 최대 1mm 정도 발생하였다. 인발하중의 83%를 풍화암층에서 그리고 12%를 연암층에서 지지하는 것으로 나타났으며 풍화암에 소켓된 철근콘크리트부와 연암에 소켓된 털근콘크리트부에서 각각 125.3kPa와 61.8kPa의 인발응력이 발생하였다. 따라서, 풍화암층에서도 인발하중을 충분하게 지지하고 있으므로 풍화암층은 마찰력을 크게 발휘하는 지지층으로 사용되었다.

• 한국지반공학회논문집
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• 제33권12호
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• pp.21-33
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• 2017

본 연구에서는 항타시공성(BPM, blow per meter)을 고려하여 대구경 항타강관말뚝을 시공하였을 때 발생하는 폐색효과를 분석하였다. Coupled Eulerian-Lagrangian(CEL)해석 시 적용된 항타에너지는 파동방정식을 이용하여 산정하였고, CEL 대변형 3차원 유한요소 해석을 수행하여 말뚝 항타시공 과정을 모사하였다. 본 연구 결과, 말뚝 직경이 증가함에 따라 목표 깊이까지 소요되는 항타에너지는 증가(일정한 BPM인 경우에 해당함) 하였으며, 그 결과 soil plugging index(SPI)는 서로 유사하게 나타나지만 폐색효과는 감소함을 알 수 있었다. 또한, 말뚝의 근입 깊이가 증가할수록 SPI는 서로 유사한 값을 나타냈으나 관내토에서 발생하는 수평토압이 증가하게 되어 폐색효과는 오히려 증가하는 것으로 나타났다. 본 연구결과, 폐색효과의 대표적 영향인자인 말뚝 직경, 말뚝 근입 깊이, 지반 탄성계수, BPM에 따른 관내토의 수평토압계수 분포 경향을 제안하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.11-19
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• 2004

When pile foundation constructed by driving method, it is desirable to perform monitoring and estimation of pile drivability and bearing capacity using some suitable tools. Dynamic Pile Monitoring yields information regarding the hammer, driving system, and pile and soil behaviour that can be used to confirm the assumptions of wave equation analysis. Dynamic Pile Monitoring is performed with the Pile Driving Analyser. The Pile Driving Analyser (PDA) uses wave propagation theory to compute numerous variables that fully describe the condition of the hammer-pile-soil system in real time, following each hammer impact. This approach allows immediate field verification of hammer performance, driving efficiency, and an estimate of pile capacity. The PDA has been used widely as a most effective control method of pile installations. A set of PDA test was performed at the site of Donghea-1 Gas Platform Jacket which is located east of Ulsan. The drilling core sediments of location of jacket subsoil are composed of mud and sand, silt. In this case study, the results of PDA test which was applied to measurement and estimation of large diameter open ended steel pipe pile driven by underwater hydraulic hammer, MHU-800S, at the marine sediments were summarized.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.351-359
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• 2010

Large PHC piles with a diameter of 1,000mm or larger were recently introduced for the first time in Korea. This paper presents full-scale static and dynamic pile load tests performed on two 1,000mm PHC piles and two composite piles with steel pipe piles of the same diameter in the upper portion, installed by driving and pre-boring. The objectives of the tests include evaluating pile drivability, load-settlement relation, allowable bearing capacity, and the stability of mechanical splicing element for the composite pile(a.k.a. non-welding joint). The performance of the large diameter PHC piles were thought to be satisfactory compared to that of middle sized PHC piles with a long history of successful applications in the domestic and foreign markets.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.291-298
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• 2001

It is very difficult to accomplish load tests of piles with large diameter constructed on the offshore area, because of requirement for large scaled loading equipment and bad testing conditions. Therefore, so far in many cases pile driving dynamic formulas have applied to quality control, and recently dynamic load test method is widely used for confirming bearing capacities of such piles. However, in cases of piles with very large diameter about 2,500mm, it is nearly impossible for regular type load test methods of piles such as static and dynamic to apply owing to very large design load. This is case studies of load tests such as modified static and dynamic load tests of piles and point load tests of rock samples for estimating rational allowable bearing capacity of very large diameter piles constructed on the marine area.