• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.377-384
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• 2008

In the bi-directional pile load test (BD PLT) for pile load test of Mega foundation, loading capacity specification were not specified exactly. Therefore there are so many confusions and variations of maximum 2 times in loading capacity are come out. In this study, specifications of bi-directional pile load test (BD PLT) were considered. Based on cases of the bi-directional pile load test performed in domestic areas, maximum equivalent test load, test load increasing ratio and sufficiency ratio of design load were analyzed. It can be known that the loading capacity specification of bi-directional pile load test must be defined as 1-directional test load that is established as more than 2 times of design load.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1156-1163
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• 2010

The bi-directional high pile load test(BDH PLT) does not have weaknesses found in the existing bi-directional low pile load test(BDL PLT); it has strong economics, is unbound by load capacity limit and secures quality stability of working piles. In this study, Verification the field found a very high capacity level of stability and reliability of the BDH PLT, as well as outstanding field applicability. Field verifications reaffirmed the advantage of the BDH PLT device, which was capable of loading 90 MN capacities as maximum. It was also found to be durable enough to load high capacity with ease.

• Journal of the Korean Geotechnical Society
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• v.23 no.6
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• pp.23-36
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• 2007

To overcome the limits of the static pile load test for large diameter drilled shafts, bi-directional low pressure pile load test (BDL PLT) has been used but this test method containes some problems that has not been solved basically. That is, BDL PLT has some problems: difficulty in jack (or cell) arrangement for large test capacity, void remain inside jack (or cell) due to the unrecovery of piston after test etc. In this study, bi-directional double-acting high pressure pile load test (BDH PLT W/DOJ) was developed and confirmed for a in-situ large diameter drilled shaft. At present, test specification of bi-directional pile load test (BDPLT) is being made, and severed main issues (such as, test kinds, test capacity, necessity of use of double-acting and attention of application to service pile) will be contained at the specification.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6C
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• pp.379-388
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• 2008

In the bi-directional pile load test (BD PLT) for pile load tests of Mega pile foundations, loading capacity standard is not specified exactly. Therefore there are so many confusions in performing the BD PLT and variations up to maximum 2 times in loading capacity are come out. In this study, standards of bi-directional pile load test (BD PLT) were considered. Based on cases of the bi-directional pile load test performed in domestic areas, maximum equivalent test load, test load increasing ratio, loading capacity increasing ratio and sufficiency ratio of design load were analyzed. It could be known that the loading capacity standard of bi-directional pile load test must be defined as 1-directional loading capacity and also must be established as more than 2 times of design load.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1088-1093
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• 2010

The Smart bi-directional pile load test with variable end plate overcomes the shortcoming of the Osterberg cell test. It is possible that the ultimate bearing capacity of piles can be known by using two different end plates. The first step is to measure end bearing capacity with smaller end plate and the second step is similar to the conventional O-cell test. In this study, model test was performed to evaluate the smart bi-directional pile load test in sand. Vertical displacement of the model pile were messured at the axial loading condition.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.603-608
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• 2006

In this paper, principal concepts on bi-directional pile load test(BD PLT) specification were explained. These main concepts are kinds of BD PLT, loading capacity, reporting the test results to relevant association etc.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5C
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• pp.303-311
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• 2008

In the case of bi-directional high pressure pile load test with double-acting jack, the shortcomings of bi-directional pile load test with single-acting jack could be solved, low-cost of test could be sure, the limits of loading capacity could be overcome and quality assurance of service plie could be confirmed. In this study, to confirm the stability, the reliability and the application of bi-directional high pressure pile load test with double-acting jack, the calibration test for high pressure oil jacks, the length of high pressure hose and tunable high pressure pipe system were performed. As a result, credibility was very high because the reliability of test results was approached at about 1.0.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.518-525
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• 2009

The bi-directional high pressure pile load test(BDH PLT) which is a kind of pile load tests was conducted to find out a reasonable design procedure of large-diameter drilled shafts of large-size building structures. The behaviors of bearing capacity and settlement of the large-diameter drilled shafts were analyzed and the results obtained from BDH PLT were also compared with those obtained from the equations suggested in the specification. In case of the reasonable design procedure adopted, the construction cost could be saved at least 15 ~ 28%. It could be concluded that BDH PLT should be needed for the foundation construction cost reduction of the high-rise building structures.

• Journal of the Korean GEO-environmental Society
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• v.14 no.9
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• pp.5-12
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• 2013

In this study, each top-down load test and bi-directional load test has been performed on the 480mm diameter of two rock socketed drilled shafts, which are located next to each other, and the results have been compared. The result shows that the settlement from the equivalent load-settlement curve of bi-directional load test is smaller than one from top-down load test, because elastic is not considered in equivalent load-settlement curve of bi-directional load test. Therefore elastic shortening should be considered to obtain appropriate equivalent load-settlement curve. Three existing methods used to obtain equivalent load-settlement curve with consideration of elastic shortening has been compared with the result of top-down load test. The result shows that those existing methods are sufficiently applicable to the design. In addition, result of comparison between top-down load test and bi-directional load test shows that bi-directional load test was found to overestimate bearing capacity because it does not consider pile body failure.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.748-753
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• 2008

Bi-directional load test is one of O-cell tests. The O-cell test is a system which may be used for performing static load tests on cast in situ reinforced concrete bored piles. The technique was devised and developed by Osterberg of Northwestern University(USA) and has been in use around the world. The principle of the method is that an O-cell is installed in a cast in situ bored pile base. Once the pile concrete reaches its design strength the cell is connected to an hydraulic pump and pressured. Pressurisation causes the cell to expand, developing an upward force on the section of pile above the cell loads, pile movements and strains within the pile then enable the capacity of the pile and its load settlement curves to be ascertained. Bi-directional load tests using O-cell are now becoming common practice around the world, particularly where the loads to be applied are high or where it is not convenient to perform top-down loading tests. In the study, calculate ultimate capacity of bi-directional load test using FEM and beam on elasto-plastic foundation theory.