• Journal of Ocean Engineering and Technology
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• v.17 no.4
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• pp.43-51
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• 2003

The resistance mechanism of anchor changes according to the types of anchor. Friction anchors are classified into tension and compression types. In this study, the characteristics and mechanism of pullout are analysed, and the design method of anchor and computer program for design are developed through compression test results of anchor body grout. The characteristics of compression anchor, compared with tension anchor, are summarized mainly as follows: (1) The effect of progressive failure of compression anchor body are much smaller than those of tension anchor during pullout of anchor: (2) The skin friction resistance is increased by Possion effect of grout (anchor body) during pullout of compression anchor.

• Geotechnical Engineering
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• v.12 no.4
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• pp.87-100
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• 1996

The pull -out test has been used to investigate the friction properties between soil and grid type geosynthetics which is useful to measure the passive bearing resistance as well as the skin friction. In this paper, the friction properties between geogrid and a weathered granite soil are investigated by performing various pull-out tests. From the test results, a rational pull out test equipment and test method is suggested by evaluating the effects of major factors (such as geogrid width, location of soil box facing, vertical loads and pulll -out displacement rate, etc.) on pull -out test results.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.307-314
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• 2001

The bearing capacity of drilled shafts that take excavation by Percussion Rrotary Drilling(PRD) into consideration was evaluated using static and dynamic pile load tests. The emphasis was on quantifying the allowable bearing capacity and point load-transfer at the pile tip on seven instrumented steel piles. Of the seven instrumented piles, five piles are placed to the bottom of the excavation by rotary and pushing into the final depth of the excavation, as opposed to the two driven piles. Based on the results obtained, it is shown that the skin friction mobilized by PRD is much greater than point resistance, whereas in driven piles, the point resistance is greater than skin friction. It is also found that much greater pile capacity was proved in the case of drilled shafts, compared to the driven piles and thus, the excavation by rotary drilling gives reliable pile capacity required to design axially loaded piles.

• Geotechnical Engineering
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• v.8 no.2
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• pp.21-30
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• 1992

Though the pile skin friction can take substantial amount of load carrying capacity, it has often been ignored in the design. Even when the pile skin friction is taken into consideration, it is questionable about the reliability of estimating it. It has been even worse in Korea. since in most cases the available information is only the SPT N values and not much information has been known about the correlation between N value and the pile skin friction in residual soils. With SPLT (Simple Pile Loading Test) it is possible to measure the pile skin friction separately from the tip resistance. In this research, results of the measured pile skin friction in residual soils are analysed. And a new design correlation based on SPT N value is proposed.

• Journal of the Korean Geotechnical Society
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• v.39 no.1
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• pp.5-14
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• 2023

The pile driving process may lead to ground heaving, causing additional positive skin friction to act on the piles, compromising their stability. This study proposes a new pile foundation type that can reduce positive skin friction. This was investigated by designing and constructing a pile with a hydraulic cylinder which actively responds to ground deformation. The newly proposed pile design was compared against traditional piles in multiple model tests where ground heaving was simulated. In the tests, base load and total shaft resistance were measured during ground heaving and with expansion of the hydraulic cylinder. As a result of the tests, a very small amount of expansion of the hydraulic cylinder member completely reduced the positive skin friction and increased the base load. Excessive expansion of the hydraulic cylinder, however, generates negative skin friction beyond the zero skin friction state. Therefore, it is necessary to estimate the appropriate level of hydraulic cylinder expansion, taking into account the amount of ground heaving and the allowable displacement of the pile.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.249-258
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• 1999

Dynamic load and static load tests are performed on steel pipe piles and concrete piles at five construction sites in highway to compare the difference of load bearing mechanisms. At each site, one steel pile is instrumented with electric strain gages and dynamic tests are performed on the pile during installation. Damages of strain gages due to the installation are checked and static test is performed upon the same pile after two or seven days as well. It shows that load transfer from side friction to base resistance behaves somewhat differently according to the results of load-settlement analysis obtained from PDA and static load test. Initial elastic stage of load settlement curves of two load tests is almost similar. But after the yielding point, dynamic resistance of pile behaves more stiffer than static resistance, thus, dynamic load test result might overestimate the real pile capacity compared with static result. Analysis of gage readings shows that unit skin friction increases exponentially with depth. The skin friction is mobilized at the 1∼2m above the pile tip and contributes to the considerable side resistance. Comparison of side and base resistances between the measured value and the calculated value by Meyerhof's bearing capacity equation using SPT N value shows that the calculated base resistance is higher than the measured. Therefore, contribution of side resistance to total capacity shouldn't be ignored or underestimated. Finally, based upon the overall test results, a construction control procedure is suggested.

• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.107-117
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• 2020

Open-ended steel pipe piles have outside frictional force and inside frictional resistance in which blocked soil acts on the inside of the steel pipe during installation. It is expected that the ultimate load will change depending on the inside and outside resistance. And, if the ground on which the piles were constructed is clay soil, it is predicted that it will have effect on the negative skin friction caused by the ground settlement. Therefore, in this study, the behavior according to the inside and outside resistance characteristics of steel pipe piles was analyzed numerically, and the frictional force distribution, axial load and settlements before and after the occurrence of ground settlement were calculated. As a result of the analysis, the inside frictional resistance had less influence than the outside frictional resistance. However, inside frictional resistance is considered to be one of the important factors considering the effect on the overall pile behavior, and both resistance factors need to be considered in the design process.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.17-24
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• 2005

Recently construction activities increase in reclaimed onshore areas. It is therefore considered an important factor for the design of pile foundation with problems in terms of settlements due to soft grounds. Nevertheless the design of piles for negative skin friction(or downdrag forces) is probably poorly understood by many engineers. It is mainly because the most of design specification give a way to design pile foundation in bearing capacity aspect although the negative skin friction is related to settlement(downdrag). Under LRFD(load resistance factor design) approach it is to separately consider ultimate limit state and serviceability limit state. This paper discusses LRFD approach to the design of piles for negative skin friction and compares this approach to traditional design approach. And also a case history is analyzed in that point of view.

• Geotechnical Engineering
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• v.14 no.5
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• pp.163-172
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• 1998

To study the carrying capacity behavior of pile, dynamic pile testis and static load tests were carried out on two instrumented piles during and some time after pile driving. Cone Penetration Test( CPT) and Standard Penetration Test(SPT) were also performed at the test site before pile tests to investigate the relationship between unit skin friction of piles and cone tip resistance values and SPT N values. Total static capacity of pile reached the ultimate stage at the pile head settlement of about 0.055D (D : Pile diameter), at which skin friction of Pile already Passed the maximum value, but the end bearing was still increasing with the pile head settlement. The carrying capacity of pile increased in the form of natural logarithmic function with the time after pile driving. The increase in skin friction with time was very substantial the increase in skin friction 40 days after pile driving was 4.6 times of that determined during pile driving. The contribution of skin friction to the total capacity twas insignificant in the beginning, but became substantial 40 days after pile driving. This implies that the tested pile initially responded as an end bearing pile and later behaved as a friction pile. It was also noted that unit skin friction of pile might be ielated to cone tip resistance values(q.) and SPT N values, though the coefficient of this relationship might differ from one soil group to another and was somewhat greater than the value used in the design practice of Korea.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.74-75
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• 2014

In remodeling business or construction of both new strucures and existing structures, Case that pile foundation was set is often. Micro pile, holding compressive force and tensile force by spherical friction, is supported by skin friction rather than end bearing capacity. but, This is weak in tension. Active area of micro pile's skin friction is narrow and micro pile don't do unification behavior hence. So bearing capacity was not fully mobilized in existing researching. In this study, in order to compensate for this method, micro pile to install Resisting Fixture is proposed.