• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.285-292
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• 2000

Though there has been increasing use of large diameter drilled shaft as a foundation structure of bridges, current practice for quality control is to confirm the minimum required load carrying capacity during construction stage. For economic and appropriate design of drilled shaft, it is necessary to evaluate the load transfer mechanism by pile load tests during initial stage of construction and to use the test results as a feedback to a revision of initial design. In this paper, results of load tests peformed at several domestic sites are presented to investigate the load transfer characteristics of large diameter drilled shaft. It was found that most of the load on piles is sustained by shaft friction and that only small portion of the load reaches the bottom of the drilled shaft. Some test results of drilled shaft by Pile Driving Analyzer performed at same sites are also presented to compare the load transfer characteristics interpreted from static pile load tests.

• 한국지반환경공학회 논문집
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• 제16권1호
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• pp.5-16
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• 2015

장대교량의 공사비에서 대형 해상기초가 차지하는 비중은 약 40% 수준이다(KICTEP, 2007). 본 연구에서는 가상의 초장대 사장교에서 대수심 대형 복합기초에 대하여 3가지 설계법(허용응력 설계, LRFD 설계, 유로코드 설계)으로 설계검토를 실시하였고, 3차원 유한요소 해석을 통하여 대구경 현장타설말뚝의 거동에 관한 연구를 수행하였다. 그 결과, 허용응력 설계에서 추정한 방법이 연암 소켓길이가 가장 길었다. LRFD와 유로코드 설계법 2에 의해 계산된 연암소켓 길이는 유사하였다. 대구경 현장타설말뚝의 연암소켓길이가 길어짐에 따라 대구경 현장타설말뚝 두부에 작용하는 축력은 작아졌으며 현장타설말뚝의 침하량도 작아졌다.

• 한국지반신소재학회논문집
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• 제19권2호
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• pp.1-11
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• 2020

대구경 현장타설말뚝의 수평지지 특성은 말뚝의 강성, 인접지반의 수평지반반력에 따라 크게 좌우된다. 특히 말뚝설계 시 많이 활용되는 경험적인 수평지반반력계수는 그 결과의 값에 따라서 지지력의 차이가 크므로 수평지지력을 평가하는 데 매우 중요한 요소임에도 불구하고 대구경 현장타설말뚝에 대한 지반반력계수의 평가가 미흡한 실정이다. 또한, 말뚝의 취약부인 수평하중에 대한 영향범위와 최대 모멘트의 발생위치는 서로 상관관계가 있을 수 있고, 수평하중에 대한 말뚝의 보강영역을 판단하는데 주요 고려사항임에도 기존 연구에서는 이 관계에 대해 평가되지 않았다. 이에 본 연구는 대구경 현장타설말뚝의 수평지반반력계수를 평가하고, 말뚝의 영향범위(1/β)와 최대 모멘트의 발생위치(z_m)의 관계를 조사하고자 대구경 현장타설말뚝에 대한 현장시험과 비선형 해석을 수행하였다. 연구결과, 대구경 현장타설말뚝의 수평지지력은 경험식을 통한 산정결과에 따라 최대 190%정도 차이를 보였다. 또한, 말뚝의 수평거동에 대한 영향범위와 최대 모멘트의 발생위치의 관계는 지반조건에 따라 선형적 관계인 것으로 평가되었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.36-43
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• 2004

Most of pile foundations are fixed head condition, but lateral loading test for pile is performed under free head condition generally In this study, a lateral loading test for a large diameter drilled shaft was performed under the fixed pile head and the free pile head condition, where lateral displacement along the pile depth was measure. Test results and theoretical values were compared and analyzed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.486-493
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• 2006

This paper deals with the procedure and the results on the dynamic loading tests of two large diameter - long drilled shafts (diameter=2.0m, length=75m) which were embedded into weathered rocks through thick soft marine clays and sandy gravels. Prior to the real dynamic loading test, the numerical simulation for the test procedure was performed to check the structural stability of the main pile body using equivalent static elastic analysis and the application of the hammer system using WEAP (Wave Equation Analysis of Pile Driving). Through these preliminary analyses the dynamic loading tests on large diameter - long drilled shafts have been successfully achieved.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 가을 학술발표회 논문집
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• pp.431-438
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• 1999

Vertical congressive and horizontal pile load tests were performed to a instrumented large diameter (D : 1,000 mm) drilled shaft. A drilled shaft was penetrated into the weathered soil and weathered rock. PMT was done for evaluation of properties for these strata. It was expected to be difficult to get undisturbed samples of weathered soils and rocks. Thus. PMT was done at the several selected depths. In those strata, to prevent the test bore hole from collapsing, bentonite slurry was used for making the test bore hole. In this study. soil properties was evaluated by means of PMT results and estimating method (direct method, the Memard method) of vertical pile capacity and horizontal pile behaviors were summarized. Also, vertical and horizontal pile capacity were calculated using PMT and pile load test results.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.74-81
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• 2004

In this study, static end loading tests with load transfer measurement were accomplished for large diameter drilled shaft constructed in fault zone. Yield pile capacity (or ultimate pile capacity) from load-settlement curve was determined and axial load transfer behavior was measurd. The end bearing capacity was increased 2 times due to grouting the toe ground under pile base.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.9-16
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• 2005

The purpose of this study is to investigate the settlement characteristics of large drilled shafts embedded into bed rocks. To perform this research, 35 pile load test results for the large drilled shafts are used, because these deep foundations generally used as substructure systems for grand bridges. In case of the yield load can not be easily determined by load(P)-settlement(S) curve from the pile load test at the maximum loads, the standard settlements which can determine a yield load is established. The residual settlement equation of pile embedded in gneiss and igneous rocks is presented in this study. Also a equation is proposed to characterize the relationship between loads and elastic settlements in pile load tests on the large drilled shaft embedded into bedrock. Then, large drilled shaft's settlement characteristics are examined on pile length, pile diameter and pile's socked depth into rock at the pile tip.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 추계 학술발표회
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• pp.409-429
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• 2006

In designing rock-socketed drilled shaft, bearing capacity evaluation is very important because the maximum values of base and side resistance are not generally mobilized at the same value of displacement, FHWA and AASHTO code suggest different ultimate bearing capacity formular according to rock type and shaft settlement. In domestic code suggest base resistance and side resistance can be added on condition that after confirming the result of field load test with axial load transfer test. This paper shows that static load test and hi-directional load test result analysis of deep rock-socketed drilled shaft in three different sites. Load-settlement curve, t-z, and q-w curve in rock-socketed part were calculated and compared. t-z curve in weathered and soft rock showed no deflection softening behavior in pretty large strain (about 2-3% of diameter). Ultimate resistance could be the summation of side resistance and base resistance in rock-socketed drilled shaft in domestic sites.

• 한국지반공학회논문집
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• 제20권5호
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• pp.135-143
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• 2004

해상교량건설 현장의 육상구간에서 예기치 않게 발견된 단층파쇄대에 시공된 대구경 현장타설말뚝의 선단지지력을 확인하기 위하여 양방향 선단재하시험을 실시하였다. 본 연구의 목적은 단층파쇄대에 시공된 대구경 현장타설말뚝에 재하시험을 실시하여 단층파쇄대에서의 선단지지력을 확인하고, 그 후 말뚝 선단 하부지반에 보강 그라우팅을 실시하여 선단보강에 의한 선단지지력 증가효과를 확인하는 것이다. 선단보강 그라우팅 후 선단지지력은 2배 이상 증가하였으며 보강전 보다 선단의 침하량이 현저하게 줄어드는 것을 확인할 수 있었다.