• Journal of the Korean GEO-environmental Society
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• v.4 no.1
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• pp.59-66
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• 2003

The environmental problem due to the pile driving, the use of low noise-vibration auger-drilled pilling is increasing to solve noise and vibration problem in pilling. Therefore, in Korea, SIP (Soil-Cement Injected Precast Pile) method is mainly used as auger-drilled pilling. However, a proper bearing capacity evaluation formula has not been suggested, yet. In order to improve and supplement this situation, direct shear tests between SIP pile skin interface and soil were executed under various conditions. Through the analysis of test results, skin resistance characteristics of SIP were investigated thoroughly. Also, the nonlinear unit skin resistance capacity model and relative parameters evaluation formula with SM, SC soil were suggested.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.299-302
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• 2005

Generally, steel-concrete composite structures are considered very useful and powerful to resist external axial and flexural load due to its elevated capacity originated from composite action. This usefulness of composite structures can be applied to the drilled shafts of marine bridges that require large-scale such as entire pile-column system. As the basic study of this application, several design codes are analyzed and compared in this research.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6C
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• pp.359-366
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• 2008

The load distribution and deformation of pile subjected to axial loads are evaluated by a load-transfer method. The emphasis is on quantifying the effect of coupled soil resistance that is closely related to the ratio of pile diameter to soil modulus $(D/E_s)$ and the ratio of total shaft resistance against total applied load $(R_s/Q)$, in rock-socketed drilled shafts using the coupled load-transfer method. The proposed analytical method that takes into account the soil coupling effect was developed using a modified Mindlin's point load solution. Through comparisons with field case studies, it was found that the proposed method in the present study estimated reasonable load transfer behavior of pile and coupling effects due to the transfer of shaft shear loading, and thus represents a significant improvement in the prediction of load deflections of drilled shafts.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1819-1826
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• 2007

This study results of performed field load test in order to estimate the best pile length assessment and allowable bearing capacity of the pile foundation. End of initial driving(EOID) and restrike of pile dynamic loading tests were performed to calculate allowable bearing capacity of the experimental pile side and results were compared with the allowable bearing capacity estimated by theory. The results of allowable bearing capacity by EOID test is $1.08{\sim}1.21$ in the range of compared to the capacity calculated by the Structure Foundation Design Criterion. Allowable bearing Capacity by restrike of pile dynamic loading test is $1.32{\sim}1.48$ in the range of compared to the Structure Foundation Design Criterion. The Foundation Design Criterion underestimated the pile capacity. If the bearing capacity calculated by Structure Foundation Design Criterion is 100, EOID of pile dynamic loading test is 116, restrike of pile dynamic loading test is 138 for 20m pile used in this experimental.

• Journal of the Korean GEO-environmental Society
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• v.4 no.4
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• pp.73-84
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• 2003

In this study, the economic pile design procedure using the proof test results was proposed. In order to improve the inappropriate pile design routine, the proof test for 6 pile cases were performed and the construction saving effect were analyzed. The saving rate of construction cost with the small diameter piles and the large diameter drilled shafts were 34 - 47 and 0 - 55 %, respectively.

• Journal of the Korean Geotechnical Society
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• v.27 no.7
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• pp.47-57
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• 2011

The p-y curve has been used to design pile foundations subjected to lateral loading. Although the p-y curve has a large influence on the pile lateral behavior, p-y curves have not been clearly suggested. In this study, the p-y curve of clay was evaluated for drilled shafts in marine deposits by using 3-dimensional numerical analyses. First, the optimization study was performed to properly determine boundary extent, mesh size, and interface stiffness. The numerical modeling in the study was verified by comparing the calculated and the pile loading test results. Then, the p-y curves of single and group piles were evaluated from the parametric study. The selected parameters were pile diameter, pile Young's modulus and pile head fixed condition for a single pile, and pile spacing for group piles. Finally, the p-multiplier was evaluated by comparing the p-y curves of a single pile and group piles. As a result, the p-multiplier at pile spacing of 3D was 0.83, 0.67 and 0.78 for the front, middle, and back row piles, respectively, and showed values similar to those of O'Neill and Reese (1999). For the pile group with pile spacing larger than 60, the group effect can be ignorable.

• Journal of the Korean GEO-environmental Society
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• v.6 no.1
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• pp.45-51
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• 2005

The distribution of shaft resistance is measured by the static load test with the strain gauge or stress gauge, so that the long-term load distribution must be considered for the pile design. However, the measurement by strain gauge generally assumes the 'zero reading', which is the reading taken at 'zero time' with 'zero' load and the residual stress, which is the negative skin friction(or the negative shaft resistance) caused by the pile construction, is neglected. Therefore, the measured value by strain gauge is different from the true load-distribution because residual stresses were neglected. In this study, the three drilled shafts were constructed, and the strain measurements were carried out just after shaft construction. As a result of this study, it is shown that the true load-distribution of drilled shaft is quite different with known load distribution and the true load-distribution of drilled shaft changed from the negative skin friction to the positive skin according to the load increment.

• Earthquakes and Structures
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• v.11 no.1
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• pp.141-163
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• 2016

Fiber models have been developed and applied to various structural elements such as shear walls, beams and columns. Only scarcely have fiber models been applied to circular foundation systems such as cast in drilled holes shafts (CIDH). In pile foundations with constraint head boundary conditions, shear deformations can easily contribute to the lateral pile response. However, soil structure interaction formulations such as the p-y method, commonly used for lateral pile design, do not include structural shear deformations in its traditional derivation method. A fiber model that couples shear and axial-bending behavior, originally developed for wall elements was modified and validated on circular cross sections (columns) before being applied to a 0.61 m diameter reinforced concrete (RC) pile with fixed head boundary conditions. The analytical response was compared to measured test results of a fixed head test pile to investigate the possible impact of pile shear deformations on the displacement, shear, and moment profiles of the pile. Results showed that shear displacements and forces are not negligible and suggest that nonlinear shear deformations for RC piles should be considered for fixed-head or similar conditions. Appropriate sensor layout is recommended to capture shear deformation when deriving p-y curves from field measurements.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1100-1105
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• 2008

In most drilled shafts construction sites, it is common, depending on the site condition, to use either water or slurry as fluids for maintaining stability of the holes, however, there are yet no design manuals by hole stability fluids. In this paper, in order to evaluate load transfer characteristics of the drilled shafts by hole stability fluids, two test piles are constructed over the soft ground of the lower Busan Bay based on the Bi-directional Pile Load Test. The test results showed that no ultimate states has found under the condition of applied loads with fresh water and slurry as hole fluids for drilled shafts. Then, the load transfer behavior were estimated with the data measured in fields and the effect of hole stability fluids were compared. All these results are presented in the paper.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2000.09a
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• pp.211-222
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• 2000

The design values of rock socketed pile related with properties of rock mass are not clearly established. However, the drilled shafts socketed in rock are widely used as the foundation of large scaled structure. In this study, the characteristics of behavior of rock socketed pile is researched, and the properties of interface between pile and rock considering soil-structure interaction are evaluated for numerical modeling of rock socketed pile based on the previous researches. Based on the properties of interface and rock mass, the behaviors of rock socketed piles are numerically modeled and compared with field measurement. To verify the numerical analysis, a micro pile socketed in rock is modeled and the results of numerical analysis are compared with field measurement. The numerical results show a good agreement with field measured data, especially in terms of load transfer characteristics.