• Journal of the Korean Geotechnical Society
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• v.38 no.4
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• pp.21-32
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• 2022

Steel pile foundations are widely used for offshore constructions due to their high bearing capacity and efficiency. Typically, offshore structures that have reached the end of their design life are required to be demolished. However, pile foundations are often left on site due to technical and economic limitations. The pile left on the site not only pollutes the environment, but can also cause obstacles for the construction of new structures. Therefore, research is required to completely eliminate these foundations at the site. In this study, a new type of double-wall pile foundation that can drastically reduce the pull-out load was conceptually proposed, and a series of model tests were performed to validate the performance of the double-wall pile foundation. The installation and extraction of the double-wall pile were simulated in dry sand in the model test, and the measured up-lift load was compared to that of the conventional pile. According to the result, the maximum up-lift load induced by the decommissioning of the double-wall pile was reduced by 45% when compared to the traditional pile in dense sand. This study verified the mechanism for reducing the up-lift load of the double-wall foundation and confirmed the possibility of completely decommissioning a pile that has reached the end of its nominal service life.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.681-688
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• 2002

Study was peformed to develop the‘environmental double pile’for the remediation of low-permeable contaminated soil. This technique is similar in function to‘sand drain pile’But this applies recyclable oyster shell treated as waste materials to a drain material and the pile is consisted of two layers. Inner metal pile is located in center and oyster shells are filled around it. By this technology, contaminated ground water is pumped out through the oyster shell and purified by drainage, adsorption, and reaction processes. Afterwards, the grout material is injected through the inner pile for the effect of the solidification / stabilization. As a result, the concept of this technique is a development of one-step process technology. Through the test, a consolidation characteristic by radial drain is going to be evaluated and the optimum standard of this technology will be calculated.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.243-252
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• 2003

Environmental Double Pile method was presented as a device to improve low permeable contaminated soil. EDP is one of the latest technology in a concept of one step process that is applied to low permeable contaminated ground to reutilize the site by enhancing drainage, contaminated remediation, bearing capacity of piles. In order to evaluate on-site applicability of this technology, qualities of EDP's drainage, strength and remediation were assessed through a series of experiments; EDP was verified to achieve remediation and improvement of soft ground.

• Journal of the Korean GEO-environmental Society
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• v.23 no.12
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• pp.5-15
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• 2022

Conventionally, because evaluation methods of the bearing capacity for double steel pipe-concrete composite pile design have not been established, the conventional vertical bearing capacity equations for steel hollow pile are used. However, there are severe differences between the predictions from these equations, and the most conservative one among vertical bearing capacity predictions are conventionally adopted as a design value. Consequently, the current prediction method for vertical bearing capacity of composite pile prediction composite pile causes design reliability and economical feasibility to be low. This paper investigated mechanical behaviors of a new composite pile, with a cross-section composed of double steel pipes filled with concrete (DSCT), vertical bearing capacities were analyzed for several DSCT pile conditions. Axisymmetric finite element models for DSCT pile and surrounding ground were created and they were used to analyze effects on behaviors of DSCT pile pile by embedding depth, stiffness of plugging material at pile tip, height of plugging material at pile tip, and rockbed material. Additionally, results from conventional design prediction equations for vertical bearing capacity at steel hollow pile tip were compared with that from numerical results, and the use of the conventional equations for steel hollow pile was examined to apply to that for DSCT pile.

• 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.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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.1
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• pp.119-128
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• 2015

This study investigates the wave pressure characteristics of the pile-supported breakwater with single or double perforated walls through 2-D hydraulic experiments and the measured wave pressures are compared to those of wave pressures by Goda's formula. For single chamber, the measured wave pressures in the front wall and rear wall decreased to about 25% and 30%, respectively, compared to those of wave pressures by Goda's formula. Also, the decrease in the wave pressures for double chamber were about 27%, 53%, and 64% in the front wall, middle wall, and rear wall, respectively. It was found that the pile-supported breakwater with double perforated walls was more efficient than the single chamber due to wave dissipation effects of double slit walls with horizontal slits.

• Journal of the Korean GEO-environmental Society
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• v.12 no.10
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• pp.63-72
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• 2011

The high capacity bi-directional pile load test is an optimum pile load test method for high-rised buildings. Especially, a high pressure and double-acting bi-directional pile load testing, a special type of the high capacity bi-directional pile load test, is the most practical way to overcome limitations of loading capacities and constraints of field conditions, which was judged to be a very useful test method for requiring high loading capacities. Total of 2 high capacity bi-directional pile load tests(P-1 and P-2) were conducted in high-rised building sites in Korea. Based on the field load test results, the sufficiency ratio of loading capacities to design loads for P-1 and P-2 were 3.3 and 2.1, respectively. For P-2, the load test could not verify the design load if 1-directional loads applied slightly smaller than the actual applied load. Also, high capacity bi-directional pile load tests were difficult to determine an ultimate state of ground or piles, although the loads were applied until their maximum loads. Hence, finite element analyses were conducted to determine their ultimate states by calibrating and extrapolate with test results.

• Journal of the Korean Geotechnical Society
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• v.30 no.12
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• pp.51-61
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• 2014

This paper presents an experimental study of the plugging effect on the capacity of open-ended piles installed in sandy soil. Full-scale tests, including dynamic and static axial-compression load tests, were carried out on three instrumented piles with different diameters (508.0, 711.2 and 914.4 mm). To measure the outer and inner shaft resistances acting on the piles, a double-walled system was utilized with instrumented strain gauges on the outside and inside walls of the pile. The results of field tests show that the inner shaft resistance was mostly mobilized at the location between the pile tip and 18-34% of the total plug length. It was found that the soil plugging in the lower portion has influence on the inner shaft resistance. In addition, it can be also demonstrated that the ratio of inner shaft resistance plus annulus load resistance to total resistance decreased with increasing pile diameters. The results of these tests show that the relationship between the degree of plugging and pile diameter is clearly established. Direct observations of the soil plugs were made and used to quantify both the plug length ratio (PLR) and the incremental filling ratio (IFR). Based on this result, it was found that the N value of the standard penetration test (SPT) is highly correlated with the IFR.

• Journal of the Korean Geosynthetics Society
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• v.20 no.1
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• pp.1-8
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• 2021

In urban areas, structures are installed deep underground in the lower part of the structure to utilize space. Therefore, a retaining wall is used to prevent earth pressure from the ground when constructing a structure. Due to the development of construction technology, retaining wall applied to excavation work are used to prevent danger such as falling rocks and landslides in temporary facilities when construction or retaining walls are installed. In general, the application of a retaining wall to a temporary facility during the embankment construction is the case of expanding an existing roads or railways. Therefore, it is necessary to study the retaining wall applied to the embankment construction such as the double-track site of the high-speed railway. In this study, two types of common one row H-pile retaining wall and two types of IER retaining wall were analyzed, and the stability of the retaining wall applied to the construction of double-track of the high-speed railway was analyzed. The earth retaining wall is a construction method that combines forced pile applied to the stabilization of the slope with the wall of the earth retaining wall. As a result of the analysis, the IER retaining wall had maximum lateral displacement of 19.0% compared to the type with H-plie installed only in the front while dynamic load was applied. In addition, the slower the speed of high-speed railway, the more displacement occurred, and the results show that more caution is needed when designing the ground in low-speed sections.