• Journal of Industrial Technology
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• v.27 no.B
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• pp.209-214
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• 2007

This paper is the research result about centrifuge model experiments of investigating the behavior of bridge abutment on the sloped ground. Ground condition of the studied site was the bridge abutment with pile foundation adjacent to the slope. The pile foundations was supported on the soft rocks covered with the embankment. Evaluating the behavior of such a complicate ground and structure conditions was not easy so that the centrifuge modelling was performed to find the overall behavior of them. Layout of centrifuge model experiment was simplified to simulate easily the actual behavior of very complicate site condition. Construction process in field such as ground excavation for footing foundation, installation of piles, placement of footing and bridge abutment, backfilling and surcharge loading eas duplicated in the centrifuge model experiment. Consequently, the stability of the piled bridge abutment adjacent to the slope of embankment was evaluated throughout centrifuge modelling.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.11-19
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• 2004

When pile foundation constructed by driving method, it is desirable to perform monitoring and estimation of pile drivability and bearing capacity using some suitable tools. Dynamic Pile Monitoring yields information regarding the hammer, driving system, and pile and soil behaviour that can be used to confirm the assumptions of wave equation analysis. Dynamic Pile Monitoring is performed with the Pile Driving Analyser. The Pile Driving Analyser (PDA) uses wave propagation theory to compute numerous variables that fully describe the condition of the hammer-pile-soil system in real time, following each hammer impact. This approach allows immediate field verification of hammer performance, driving efficiency, and an estimate of pile capacity. The PDA has been used widely as a most effective control method of pile installations. A set of PDA test was performed at the site of Donghea-1 Gas Platform Jacket which is located east of Ulsan. The drilling core sediments of location of jacket subsoil are composed of mud and sand, silt. In this case study, the results of PDA test which was applied to measurement and estimation of large diameter open ended steel pipe pile driven by underwater hydraulic hammer, MHU-800S, at the marine sediments were summarized.

• Proceedings of the Korean Geotechical Society Conference
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• 1991.10a
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• pp.362-375
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• 1991

Background and Necessity of the study : For more than 20 years, the soil engineering reserach group of Chonnam National University has been performing the deformation analysis of soft clayey foundation, since the University is located near the south-western coast of Korean Peninsulla, along which tide reclamation works have been under proaressing. Associsted with the fact mentioned above, the researchers have been developing a computer program in order to carry out deformation analysis of soft foundation since early 1980. Case-studies : In this research, the Biot's equation was selected as the governing equation coupled with several constitutive models including original and modified Cam-clay models, elasto-viscoplastic model, Lade's model etc. The anisotropy of soi1 can be considered in this program. To validate the accuracy of the computer program developed a couple of case-studies were performed. These include the pilot banking, sand drain considering smear effect and compound foundation reinforced with sheet pile into soft foundation.i) The pilot banking Good results could be acquired by assuming banking load as the body force composed of finite element mesh rather than equivalent concentrated load.ii) The sand drain Due to smear, the delay of consolidation was remarkable at the early stsge. so safety for the failure of foundation should be checked for the initial step of consolidation. iii) The compound foundation Accurate results were obtained by introducing the joint element method for the soft foundation reinforced with sheet pile into soiㅣ.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.544-551
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• 2004

Piles are structural elements made of steel, concrete or timber, and utilize as pile foundation which is one of deep foundations. Driven pile among them, which drives pile into the ground, is fast-constructable, less expensive and it supplies much bearing capacity. For these reasons, its demand is steady. In this study, by selecting the cases which reached ultimate failure during in-situ static loading tests, bearing capacities acquired from these tests were compared with those computed by existing theories and formula. As the results of the analysis, ultimate bearing capacity computed by theoretic formula were less or similar to those of test results in most cases, but lower ground water level and more dense layer where end of piles were reached remarkably high bearing capacity in theoretical methods. ${\beta}-method$ and Korean structure foundation design standard were sensitive to ground physical properties. Meyerhof metbod and API code were relatively independent from site condition.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.700-707
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• 2008

As plan connecting island to island or island to land is needed, a lot of long-span bridge is being designed lately in Southern part of Korea. With development of pile equipment, overhanging large-scaled concrete pile are adopted to foundation type of main tower or pylon. About the number of 15~30 group piles per tower foundation is designed to resist long-spaning super-structure load, but by restricted condition of site investigation cost, a few boring-hole tests are performed to identify sub-ground layers. Up to now, direct-curved method connecting two or three known boring logs and representative interval method are usually used to evaluate unknown depth and rock properties at locations where piles are constructed. Because this approach is not logical and so rough, much difference occurs between designed length of piles and real length of it. In this paper, using a lot of various prediction method(reciprocal distance method, inverse square distance method and kriging method etc.), we suggest optimum length of group piles.

• Geomechanics and Engineering
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• v.21 no.4
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• pp.379-390
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• 2020

The behavior of a piled raft system in multi-layered soil subjected to vertical loading has been studied numerically using 3D finite element analysis. Initially, the 3D finite element model has been validated by analytically simulating the field experiments conducted on vertically loaded instrumented piled raft. Subsequently, a comprehensive parametric study has been conducted to assess the performance of a combined piled raft system in terms of optimum pile spacing and settlement of raft and piles, in multi-layered soil stratum subjected to vertical loading. It has been found that a combined pile raft system can significantly reduce the total settlement as well as the differential settlement of the raft in comparison to the raft alone. Two different arrangements below the piled raft with the same pile numbers show a significant amount of increase of load transfer of piled raft system, which is in line with the load transfer mechanism of a piled raft. A methodology for the factor of safety assessment of a combined pile raft foundation has been presented to improve the performance of piled raft based on its serviceability requirements. The findings of this study could be used as guidelines for achieving economical design for combined piled raft systems.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1489-1504
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• 2014

This paper is aimed to suggest a site specific partial safety factor of offshore wind turbine (OWT) pile foundation design for the offshore wind turbine complex at a West-South mainland sea in Korea. International offshore wind design standards such as IEC, GL, DNV, API, ISO and EUROCODE were compared with each partial safety factor and resistance factor. Soil uncertainty analysis using a large number of soil data sampled was carried out, and their results were adapted to estimate partial safety factor of OWT pile foundation through reliability analyses. The representative partial safety factor has been estimated as 1.3. When a proposed partial factor is willing to use to other sites, it is recommended that further studies on code calibration are required to validate their accuracy using more site characterization data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1271-1276
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• 2006

Vertical loads acting on corrugated metal culverts under negative arching condition were investigated through numerical analyses. Four kinds of corrugated metal culverts with span of 3m were considered in numerical analyses. Also, depths of cover were varied from 1m to 6m with increment of 1m. According to numerical analyses, magnitudes of vertical loads acting on culverts under the condition of negative arching were similar as overburden load on culvert. Furthermore, magnitudes of vertical loads acting on culverts supported by pile foundation were similar as those without pile foundation when depths of cover were less than about 2m. For larger depths of cover which are greater than about two times of span of culvert, magnitudes of vertical loads were slightly larger than those without pile foundation and its tendency becomes more clear as flexural rigidity of corrugated metal increases.

• Land and Housing Review
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• v.3 no.2
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• pp.177-185
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• 2012

LH applies a uniformly standardized PHC Pile to 15~25 stories of Shear-wall type Apartment Building. Recently it is predicted that LH will construct over 30~40 story Apartment Building to keep varied project condition and faces urgent needs to save construction cost for improving its competitiveness. Therefore, structural analysis and design on the upper part and foundation of apartment building were carried out in this study by subdividing story of apartment building, e.g. 15, 20, 25, 30, 35, 40 stories. Reflecting the result of basement analysis and design, the economic evaluations are performed and the optimum diameters of PHC piles are suggested. The result of this paper is considered to be applied usefully for foundation design of LH apartment housing, and the suggested PHC Piles can be used effectively by increasing efficiency and saving the construction cost of foundation.

• Journal of the Korean Geotechnical Society
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• v.25 no.11
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• pp.17-26
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• 2009

The concrete cap, which was established on the top of the micropile, usually considered as an important structural component in micropile supported foundation systems. However, relatively few studies have been made on the load sharing behavior of the capped micropile foundation systems. The primary objective of this study is to assess the load sharing behavior of the capped micropile foundation systems. Therefore, a full-scale test on an instrumented capped micropile is conducted for establishing the load-displacement responses. Nonlinear numerical method was used to quantify the load sharing behavior of the pile cap and micropile respectively. As a result, it was found that the pile cap shares about 50% load from final loading steps in the case of 2 by 1 micropile foundation systems. In the case of 2 by 2, the pile cap shares about 30% load from final loading steps. In addition, the load sharing behavior of the micropile cap becomes larger with an increase in spacing and the battered angle of micropile respectively.