• Proceedings of the Korean Geotechical Society Conference
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• 1994.09a
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• pp.87-93
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• 1994

Factors which affect the capacity and the soil plug condition of an open-ended pile can be broadly divided into three categories:i.e., pile conditions, soil conditions and penetration methods. It has been found that the relative density and the horizontal stress have much effects on the soil plug behavior than other soil conditions. Also, it has been found that the pile diameter is the most important factor among pile conditions. However, a few investigations have been performed to account for both soil conditions and pile conditions. In this paper, a number of calibration chamber tests have been conducted with three different sized open-ended model piles. The model pile was driven into siliceous sand, with varying soil conditions, to clarify coupled effects of pile diameter and soil conditions on the plug behavior, the capacity, and the load trasfer mechanixm of soil plug. The model piles are composed of two stainless steel pipes so as to measure the plug capacity, the tip resistance, and the outside skin friction. separately.

• Geotechnical Engineering
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• v.11 no.4
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• pp.75-86
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• 1995

After open -ended model pipe pile, which was composed of inner tube and outer tube was driven by different installation methods, degradation in open -ended pipe pile capacity was studied during simulated horizontal seismic shaking, which was modeled by records of actual earthquake. Drgradation in ultimate capacity of open -ended pipe pile during simulated earthquake was about 20% in impact pile and was approached up to about 40% in vibratal pile. Most of degradation in ultimate pile capacity was occured in the outer shaft surface and degradations in outer skin friction, toe resistance of steel, and plugging force were about 80%, 10%, 10%, respectively. out of ultimate pile capacity. It appeared that this trend did not depend upon the different installation methods of pile.

• Journal of the Korean Geotechnical Society
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• v.15 no.1
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• pp.5-13
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• 1999

Maximum stress in pile is developed when it is driven. If the stress is greater than allowable stress of the pile, the pile will be damaged and result in stability problem. Therefore, the stress should be estimated correctly beforehand and overstress should be prevented during pile driving. There are many methods to estimate compressive stresses in concrete piles when they are driven. Nowadays, computer analysis on wave equation offers a satisfactory results. But. under certain circumstances, application of this method is difficult. Then, estimation of the stress utilizing simple formulae might be practical. In this study, relatively reasonable formulae were selected and the stresses which were measured in situ and calculated from the formulae were compared and analysed. The results show that the calculated values from Uto and Huyuki's formula were reasonably accurate and more accurate values were acquired if the values are modified by multiplying the reduction factors according to ground and construction conditions.

• Proceedings of the Korean Geotechical Society Conference
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• 1998.10a
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• pp.137-144
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• 1998

• Proceedings of the Korean Geotechical Society Conference
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• 1996.10a
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• pp.351-356
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• 1996

• Proceedings of the Korean Geotechical Society Conference
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• 1996.06b
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• pp.41-76
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• 1996

• Journal of the Korean Geotechnical Society
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• v.28 no.4
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• pp.5-21
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• 2012

In our country, in the case of traditional design of pile foundations, only a design depending on end bearing has been performed. However, through the load transfer measurement data that have been carried out for in-situ piles, it was known that skin frictional force was mobilized greatly. In this study, through the analysis of the load transfer test cases of driven steel pipe piles and large-diameter drilled shafts, load bearing aspects of pile foundation depending on pile construction methods and pile load test methods were established. The average sharing ratios of skin frictional force were independent of pile types, pile load test methods, relative pile lengths, pile diameters and soil types. Because the average sharing ratios were over 50%, the case pile foundations mostly behaved as a friction pile and the extremely partial case pile foundation behaved as a combined load bearing pile.

• Geomechanics and Engineering
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• v.19 no.1
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• pp.79-91
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• 2019

Renewed interest in the long-term pile foundations has been driven by the increase in offshore wind turbine installation to generate renewable energy. A monopile subjected to repetitive loads experiences an evolution of displacements, pile rotation, and stress redistribution along the embedded portion of the pile. However, it is not fully understood how the embedded pile interacts with the surrounding soil elements based on different pile geometries. This study investigates the long-term soil response around offshore monopiles using finite element method. The semi-empirical numerical approach is adopted to account for the fundamental features of volumetric strain (terminal void ratio) and shear strain (shakedown and ratcheting), the strain accumulation rate, and stress obliquity. The model is tested with different strain boundary conditions and stress obliquity by relaxing four model parameters. The parametric study includes pile diameter, embedded length, and moment arm distance from the surface. Numerical results indicate that different pile geometries produce a distinct evolution of lateral displacement and stress. In particular, the repetitive lateral load increases the global lateral load resistance. Further analysis provides insight into the propagation of the shear localization from the pile tip to the ground surface.

• Geomechanics and Engineering
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• v.32 no.4
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• pp.453-462
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• 2023

Designing pile foundations subjected to the uplift forces such as buildings, oil platforms, and anchors is becoming increasingly concerned. In this paper, the conceptual design of a new type of driven piles called expanding pile is presented and assessed. Some grooves have been created in the shaft of the novel pile, and some moveable arms have been designed at the pile tip. At first, static analyses using the finite element method were performed to evaluate the effectiveness of the innovative pile on the axial bearing capacity. Then its effect on seismic behavior of moment frame is considered. Results show that the expanding arms were provided an ideal anchorage system because of the soil's noticeable locking-up effect increasing uplift bearing capacity. For example at the end of the static tensile loading procedure, displacement decrement up to 55 percent is observed. In addition, comparing the uplift bearing capacity of the usual and new pile with different lengths in sand and clay layers shows noticeable effect and sharp increase up to about two times especially in longer piles. Besides, a sensible reduction in the seismic response and the stresses in the beam-column connection between 23-36 percent are achieved that ensures better seismic behavior of the structures.

• Journal of the Korean GEO-environmental Society
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• v.4 no.3
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• pp.19-26
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• 2003

Recently, for the design of pile foundations on the soft ground condition, it is recognized that set-up effects are another important factor which influence the characteristics of bearing capacity of pile. In this paper, the thirteen dynamic pile loading tests were performed at the two different construction sites and the end of initial driving(EOID) were also performed and then restrike tests were performed after certain time lag. The H-pile, pipe pile, PHC pile are installed by driving into the loose silty soil and then restrike tests were performed. Nine days after pile driving, the bearing capacity of H and pipe pile were increased whereas there is not bearing capacity increasement with PHC pile. When the dense silty soil, the restrike test results showed that the bearing capacity of H and pipe pile increased up to 1.17 times. The 1-st and 2-nd restrike tests performed after 6 and 12 day, respectively. The results showed that the bearing capacity of PHC pile was decreased but the bearing capacity of piles were increased up to 1.38 times after 13 days with the third restrike test.