• 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.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.404-411
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• 2009

The steel pipe of steel-concrete composite piles increases the pile strength and induces the ductile failure by constraining the deformation of the inner concrete. In this research, the load-movement relations and the reinforcement effect by the outer steel pipe in the steel-concrete composite pile were analyzed by performing three-dimensional numerical analyses, which can simulate the yielding behavior of the pile material and the elasto-plastic behavior of soils. The parameters analyzed in the study include three pile materials of steel, concrete and composite, pile diameter and loading direction. As the results, the axial capacity of the composite pile was 1.9 times larger than that of the steel pipe pile and similar with that of the concrete pile. At the allowable movement criteria, the horizontal capacity of the composite pile was 1.46 times larger than that of the steel pile and 1.25 times larger than that of the concrete pile. In addition, the horizontal movement at the pile head of the composite pile was about 78% of that of the steel pile and about 53% of that of the concrete pile, which showed that the movement reduction effect of the composite pile was significant and enables the economical design of drilled shafts.

• Geomechanics and Engineering
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• v.15 no.1
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• pp.695-710
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• 2018

Formation of a soil plug in an open-ended pile is a very important factor in determining the pile behavior both during driving and during static loading. The degree of soil plugging can be represented by the incremental filling ratio (IFR) which is defined as the change in the plug length to the change of the pile embedment length. The experimental tests carried out in this research contain 138 tests that are divided as follows: 36 tests for single pile, 36 tests for pile group ($2{\times}1$), 36 tests for pile group ($2{\times}2$) and 30 pile group ($2{\times}3$). All tubular piles were tested using the poorly graded sand from the city of Karbala in Iraq. The sand was prepared at three different densities using a raining technique. Different parameters are considered such as method of installation, relative density, removal of soil plug with respect to length of plug and pile length to diameter ratio. The soil plug is removed using a new device which is manufactured to remove the soil column inside open pipe piles group installed using driving and pressing device. The principle of soil plug removal depends on suction of sand inside the pile. It was concluded that the incremental filling ratio (IFR) is changed with the changing of soil state and method of installation. For driven pipe pile group, the average IFR for piles in loose is 18% and 19.5% for L/D=12 and 15, respectively, while the average of IFR for driven piles in dense sand is 30% and 20% for L/D=12 and L/D=15 respectively. For pressed method of pile installation, the average IFR for group is zero for loose and medium sand and about 5% for dense sand. The group capacity increases with the increase of IFR. For driven pile with length of 450 mm, the average IFR % is about 30.3% in dense sand, 14% in medium and 18.3% for loose sand while when the length of pile is 300 mm, the percentage equals to 20%, 17% and 19.5%, respectively.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.198-199
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• 2017

In this paper, the applicability of PHC piles to replace Myanmar local piles were evaluated. In Myanmar, based on the size of the building, foundation design and field applications are carried out using bored pile and square pile. As a result of the analysis, the application of PHC pile is more economical than conventional bored pile or square pile which was applied in the high rise (17-story) and middle story (12-story) buildings. However, in the low - rise (8-story) building, the application of the existing square piles was found to be more economical than PHC pile.

• Journal of the Korean Society of Safety
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• v.16 no.3
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• pp.99-105
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• 2001

This paper presents results km a series of model tests oil vertically loaded single piles to compare the behaviors of H and pipe piles under the same ground condition. The aims of this paper were to compare the bearing capacity of H-pile md pipe piles under in the same ground condition and to estimate the effect of gravity acceleration and relative soil density. Relative density of soil were made to be 40%, 80% and embedded length of pile on sand was increased by 10, 12, 14, 16 times of the diameter of pile, respectively. As a results of test series, allowable load of H-pile is from 6.4% to 18.2% larger than allowable load of pipe pile in relative density 80% and from 9.1% to 39.4% larger than allowable load of pipe pile in relative density 40%. As a results of numerical analysis, we were predicted behaviour of stress-displacement of pile with model test. In the case of relative density 80% and 40%, bearing capacity of H pile represent from 17.74% to 18.6% larger than allowable load of pipe pile.

• Journal of the Korean GEO-environmental Society
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• v.10 no.5
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• pp.59-67
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• 2009

Three-dimensional (3D) numerical analyses have been conducted to study the behaviour of a single pile to tunnelling. The numerical analysis has included soil slip at the pile-soil interface. In the numerical analyses the interaction between the tunnel and the pile constructed in weathered soil and rock has been analysed. The study includes the pile settlement, the relative shear displacement between the pile and the soil and the shear stresses at the interface and the axial force on the pile. In particular, the shear stress transfer mechanism at the pile-soil interface related to the tunnel advancement has been rigorously analysed. Due to changes in the relative shear displacement at the pile-soil interface during the tunnel advancement, the shear stress and the axial force distributions along the pile have been changed. Upward shear stress developed at most part of the pile (Z/L=0.0-0.8), while downward shear stress is mobilised near the pile tip (Z/L=0.8-1.0) resulting in tensile force on the pile, where Z is the pile location and L is the pile length. Some insights into the pile behaviour to tunnelling obtained from the numerical analyses will be reported and discussed.

• Journal of the Korean GEO-environmental Society
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• v.10 no.5
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• pp.69-73
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• 2009

In this study, three dimensional numerical analyses were performed with variation of pile spacing (S=3D, 4D, 5D) to compare the behaviour of single pile and pile group with cap in granite soil. In order to compare and analyze the lateral resistance of single pile and pile group by changing pile spacing, the pile group with array of $1{\times}3$ was employed. To reduce the computation time the symmetric boundary condition was used. And Druker-Prager model and elasticity model were used for granite soil and for concrete pile and cap, respectively. Using the analyses results of pile group in granite soil under lateral loading, p-y curve for pile group and single pile with changing pile spacing was drawn. With p-y curve p-multiplier was evaluated. As a result of analysis, the value of p-multiplier was increased with increasing pile spacing under 1.0 due to pile shadow effects.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.28-35
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• 2004

Driven pile has the excellent bearing characteristics and good economics, so it is known as the comparative piling method. To use the advantages of driven pile fully, it is necessary to perform the proper construction management. Engineers must drive pile to the proper bearing layer with proper blow energy and measure the blow count and penetration per certain depth to analyze the bearing capacity and driveability. In conventional method, these parameters have been measured manually so it was difficult to get good accuracy. After PIR-D(Pile Installation Recorder-Driven Pile) was attached to the driving equipment, the hammer efficiency, blow count and penetration in blow/10cm were measured automatically. In this paper, to givethe rational judgement criteria of bearing layer, driveability, blow/10cm according to pile depth during pile driving, the some relationship between the driving resistance and ground layer distribution was analyzed. The ground investigation during piles (PHC ${\Phi}450,\;{\Phi}400\;&\;Steel\;Pile\;{\Phi}609{\ast}16t$) installation in the marine clay layer in Incheon, the sandy soil layer in Yongin and the tuff layer in Pusan was done. And measuring hammer efficiency not doing recently, we could compare hammer efficiency(Eh) by PIR-D and energy transfer ratio(ETR) by Pile Dynamic Analyzer(PDA).

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1303-1311
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• 2006

Most of the piles are designed as group piles. In certain geotechnical environments, the installation of group piles causes heaving of the already installed piles. The unfavorable effects of pile heaving on pile bearing capacity have been well known to field engineers. However not many engineers pay enough attention to this subject. According to our recent researches, not only the bearing capacity but also the pile material could be seriously damaged due to the installation of nearby piles, especially with the cases of precast concrete piles. When the pull-out force due to installation of neighboring piles acting on the already installed precast concrete pile exceeds the shaft friction, pile heaving occurs. At the same time, if the pull-out force exceeds the allowable tensile strength of the precast concrete pile, tensile failure is inevitable, which is critical for the pile integrity. In other cases the pile material was not damaged but serious relaxation occurred as the results of pile heaving. In this paper, the pull-out mechanism due to the installation of group piles is explained.

• Structural Engineering and Mechanics
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• v.49 no.4
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• pp.479-489
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• 2014

In the present study a parametric analysis is conducted to study the effect of pile dimension and soil properties on the nonlinear dynamic response of pile subjected to lateral sinusoidal load at the pile head. The study is conducted on soil-pile model of different pile diameter, pile length and soil modulus, and results are compared to get the effect. The soil-pile system is modelled using Finite element method. The programming is done in MATLAB. Time history analysis of model is done for varying non-dimensional frequency of load and the results are compared to get the non-dimensional frequency at which pile head displacement is maximum in each case. Maximum possible bending moment and soil-pile interacting forces for the dynamic excitation of the pile is also compared. When results are compared with the linear response, it is observed that non-dimensional frequency is reduced in nonlinear response on account of reduction in the soil stiffness due to yielding. Nonlinear response curve shows high amplitude as compared to linear response curve.