• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.105-112
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• 2006

Liquefaction-induced lateral spreading has been the most extensive damage to pile foundations during earthquakes. However, a case of pile failure was reported despite the fact that a large margin of safety factor was employed in their design. This means that the current seismic design method of pile is not agreeable with the actual failure mechanism of pile. Newly proposed failure mechanism of pile is a pile failure based on buckling instability. In this study, failure behavior of pile embedded in liquefied soil deposits was analyzed considering lateral spreading and buckling instability performing 1g shaking table test. As a result, it can be concluded that the pile subjected to excessive axial loads ($near\;P_{cr}$) can fail by buckling instability during liquefaction. When lateral spreading took place in sloping grounds, lateral spreading increased lateral deflection of pile and reduced the buckling load, promoting more rapid collapse. In addition, buckling shape of pile was observed. In the ease of pile buckling, hinge formed at the middle of the pile, not at the bottom. And in sloping grounds, location of hinge got loiter compared with level ground because of the effects of lateral spreading.

• Geomechanics and Engineering
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• v.35 no.2
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• pp.165-179
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• 2023

This study investigates the uplift capacity of a single vertical belled pile buried at shallow depth in dry sand. The laboratory model experiments are conducted with different pile-tip angles and relative densities. In addition, image and FEM analyses are performed to observe the failure surface of the belled pile for different pile-tip angles and relative densities. Accordingly, the uplift capacity and failure angle in the failure surface of the belled pile were found to depend on the belled pile-tip angle and relative density. A predictive model for the uplift capacity of the belled pile was proposed considering the relative density and belled pile-tip angle based on a previous limit equilibrium equation. To validate the applicability of the proposed model, the values calculated using the proposed and previous models were compared to those obtained through a laboratory model experiment. The proposed model had the best agreement with the laboratory model experiment.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.324-337
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• 2010

For the development of load and resistance factor design, reliability analysis is required to calibrate resistance factors in the framework of reliability theory. The distribution of measured-to-predicted pile resistance ratio was constructed based on only the results of load tests conducted to failure for the assessment of uncertainty regarding pile resistance and used in the conventional reliability analysis. In other words, successful pile load test (piles resisted twice their design loads without failure) results were discarded, and therefore, were not reflected in the reliability analysis. In this paper, a new systematic method based on Bayesian theory is used to update reliability index of driven steel pile piles by adding more pile load test results, even not conducted to failure, into the prior distribution of pile resistance ratio. Fifty seven static pile load tests performed to failure in Korea were compiled for the construction of prior distribution of pile resistance ratio. Reliability analyses were performed using the updated distribution of pile resistance ratio and the total load distribution using First-order Reliability Method (FORM). The challenge of this study is that the distribution updates of pile resistance ratio are possible using the load test results even not conducted to failure, and that Bayesian update are most effective when limited data are available for reliability analysis or resistance factors calibration.

• Journal of the Korean GEO-environmental Society
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• v.15 no.2
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• pp.59-66
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• 2014

This paper presents the pullout behavior of suction pile using finite difference method; and the commercial software, FLAC3D, was employed for the numerical analyses. The ultimate pullout capacity of suction pile was predicted using conventional equations, and the results were compared with the results from numerical analyses with varying pile diameter, pile length, and the undrained shear strength of clays. Based on the results from 24 analyses, it was found that the failure pattern depends not only on the drainage condition of suction pile, but also on the pile dimensions and the material properties of surrounding soils. The developed side shear (DSS) along the internal surface of the suction pile was collected from numerical analyses, which was used to classify the failure type between sliding failure and tensile failure. Regardless of the external DSS, the high internal DSS tends to result in sliding failure in the numerical analyses, which conforms well to the estimation from conventional equations.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1132-1143
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• 2008

A single Column/Shaft which extended the pile to the column of the bridge with same diameter has better safety and economical profit, but it usually has larger lateral displacement due to lateral loads such as wind, earthquake, wave, etc. A series of horizontal pile load testing were performed to study the lateral behavior of single column/shaft with varying different free lengths and embedded pile lengths. Eight instrumented test piles were cast-in-placed by bonding strain gauges at certain locations on both faces of the pile to measure bending moment, from two-way loadings. Linear variable differential transformers(LVDTs) were installed to measure the lateral pile displacement. Based on this, it is found that the test single column/shaft with different free lengths shows different failure modes. If the test pile has a longer free length, the failure occurs at the near the ground surface, but the shorter one's failure occurs at the below the ground surface.

• Computational Structural Engineering
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• v.4 no.3
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• pp.117-127
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• 1991

For the reliability analysis of offshore guyed towers for large storm events, failure of an anchor pile of the guyline system is investigated. Two failure modes of the anchor pile due to the extreme and the cyclic wave loadings are considered. The probability of failure due to the extreme anchor load is evaluated based on the first excursion probability analysis. Degradation of the pile capacity due to cyclic loadings is evaluated by using empirical fatigue curves for a driven pile in clay. The numerical results indicate that the failure probability due to the cyclic loadings can be as large as the risk due to extreme loading, particularly for the cases with the low design safety level of the pile strength and the large uncertainty of the pile resistance.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.380-383
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• 2003

Deep pile caps usually contain no transverse shear reinforcement and only small percentages of longitudinal reinforcement. The current design procedures including ACI 318-02 for the pile caps do not provide engineers with a clear understanding of the physical behavior of deep pile caps. In this study, the failure strengths of nine pile cap specimens tested to failure were evaluated using 3-dimensional strut-tie models. The analysis results obtained from the present study were compared with those obtained from several design methods, and the validity of the present method implementing 3-dimensional strut-tie models was examined.

• Proceedings of the Korean Geotechical Society Conference
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• 1988.06c
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• pp.71-123
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• 1988

The aim of this paper is to examine the end bearing capacity of a pile in cohesionless soils. The ode of failure of soil due to pile installation is assumed from experimental observation of actual soil deformation. A new solution is proposed complying with the assumed mode of failure by employing the theory of cavity expansion. The effect of curvature of failure envelope is studied in relation to tile proposed solution. The influence of a curved failure envelope becomes larger with increasing degree of curvature and the level of confining stress. This effect in some cases or reduce the end bearing capacity by tore the 80 percent compared with that given by a straight failure envelope. For practical application of tile proposed solution, the method of determining the average volume change in the plastic zone is re-evaluated. The proposed solution is confirmed by comparing the theoretical values with experimental results obtained from model pile tests in a calibration chamber. The comparison shows that the proposed solution provides a reasonable prediction of end bearing capacity for both weak and strong grained soils.

• Land and Housing Review
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• v.2 no.4
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• pp.553-558
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• 2011

Existing method protruding strands that are embedded in PHC pile to connect pile head and foundation slab shows poor constructibility. As this causes crack and damage in pile head and casualties often occurs in construction site during the work, alternative method called one-cutting method, in which pile above the ground surface and strands embedded in pile are completely cut and pile head is reinforced with rebar for connection with foundation slab, is currently adopted. However, the capacity of details for these methods are not mechanically proved. In this study, in order to suggest proper details of reinforcement for one-cutting method, failures due to lack of shear resistance between infilled concrete and PHC pile are analyzed through experiments and embedded depth with infilled concrete inside PHC pile is suggested. Assuming that slip failure strength is 0.4MPa, which is obtained from experiment conservatively, to have rebar yielded before slip failure, minimum depth of infilled concrete for PHC 450 and PHC 500, need to be 600mm above, and for PHC 600, 1,000mm above.

• Journal of the Korean Geotechnical Society
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• v.25 no.6
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• pp.59-72
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• 2009

The load distribution and deflection of offshore piles are investigated by lateral load-transfer curve method (p-y curve). Special attention is given to the soil-pile interaction and soil resistance of 3D wedge failure mode. A framework for determining a hyperbolic p-y curve is proposed based on theoretical analysis and experimental load test results. The methods for determining appropriate material parameters needed for constructing the proposed p-y curves are presented in this paper. Through comparisons with field case studies, it was found that the proposed method in the present study estimates reasonably the load transfer behavior of pile, and thus, the computed pile responses, such as bending moment and lateral displacement, agree well with the actual measured responses.