• Title/Summary/Keyword: end bearing capacity

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Evaluation of Pile Bearing Capacity and Scale Effect Using Model Pile Test (모형실험을 통한 말뚝지지력의 평가 및 치수효과의 비교분석)

  • 이인모;이정학
    • Geotechnical Engineering
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    • v.9 no.4
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    • pp.37-44
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    • 1993
  • Model pile tests in calibration chamber are performed in order to study the two factors that the pile bearing capacity is significantly influenced by. Those factors are the critical depth concept and the scale effect caused by pile diameters. Firstly, the predicted values of end bearing capacity from the various static formulae were compared with the measured ones from model pile tests. Secondly, the critical depth concept and the scale effect were investigated by using two different soil conditions in a series of calibration chamber tests : the one is uniform sand : and the other is weathered granites overlayered by sand. Main results obtained from the model tests can be summarized as follows : (1) The end bearing capacity was increased with pile penetration depth up to penetration ratio of 7 to 8 when the cell pressure is high, and the critical depth was observed in the current chamber tests with uniform sand layer , (2) The predicted end bearing capacities were mostly lager than the measured, and it was found that the differences between the predicted and the measured values became smaller as the pile penetration ratio was increased : (3) The end bearing capacity of the small diameter pile in weathered granites layer was mostly less than that of the larger pile, while in uniform sand layer it was vice.

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Estimation of End Bearing Capacity of SDA Augered Piles on Various Hearing Stratums (지지지반의 종류별 SDA매입말뚝의 선단지지력 산정)

  • Hong, Won-Pyo;Chai, Soo-Geun
    • Journal of the Korean Geotechnical Society
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    • v.23 no.5
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    • pp.111-129
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    • 2007
  • The standard construction manual of the SDA(Separated Doughnut Auger) piling method was proposed so that the resisting capacity of the augered piles could work effectively. 405 dynamic pile load tests and 30 static pile load tests were performed for 265 test piles, which were installed by the SDA piling method in 33 sites in Korea. The results of the pile load tests showed that the end bearing capacity of the SDA augered piles depended on the property of various soil stratums and did not agree with ones estimated by the existing formula based on several standard design codes. On the basis of the pile load test results, four formulas were presented according to bearing stratums to estimate quantitatively the unit end bearing capacity of the SDA augered piles. The formulas for the unit end bearing capacity of piles on soils or weathered rocks were related to N-value given by SPT(Standard Penetration Test), while the unit end bearing capacity on bedrock was suggested to be more than 1500 $tf/m^2$. The presented formulas were compared with the existing formulas, which were presented by several standard design codes to design the augered piles. In order to use correctly the presented formulas, the quality of Standard Penetration Test should be controlled precisely. Also it is desirable to choose a pilot construction site, where both dynamic and static pile load tests are performed.

Effect of N Value and Pile Length Ratio on Bearing Capacity Distribution of Cohesionless Soil (사질토 지반에서 N값과 말뚝의 길이비가 지지력 분담 특성에 미치는 영향)

  • Lee, Kwang-Wu;You, Seung-Kyong;Han, Jung-Geun;Park, Jeong-Jun;Kim, Ki-Sung;Hong, Gigwon
    • Journal of the Korean Geosynthetics Society
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    • v.19 no.1
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    • pp.65-73
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    • 2020
  • This study describes the evaluation results of pile length ratio and N value on the bearing capacity of drilled shafts in cohesionless soil. The bearing capacity ratio in Meyerhof's formula is affected only by the length ratio, and it is equally evaluated a sharing ratio of the end bearing capacity and the skin friction. NAVFAC's formula shows that the pile length influences both end bearing capacity and the skin friction, but pile length is also found to be a more influence factor on the end bearing capacity. Especially, it was found that the effect of pile length factor was larger than the effect of N value and pile diameter. FHWA's formula was evaluated to reflect the influence factor by skin friction more positively than other formulas at calculation the bearing capacity. It was also confirmed that the influence of the skin friction is larger when the ultimate bearing capacity is evaluated.

The Effect of Bearing Capacity Increasement for Driven Pile in Silt (실트지반에 타입된 말뚝의 지지력 증가효과)

  • Yeo, Byung Chul;Oh, Se Wook;Bae, Woo Seok;Ahn, Byung Chul
    • Journal of the Korean GEO-environmental Society
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    • v.4 no.3
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    • pp.19-26
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    • 2003
  • Recently, for the design of pile foundations on the soft ground condition, it is recognized that set-up effects are another important factor which influence the characteristics of bearing capacity of pile. In this paper, the thirteen dynamic pile loading tests were performed at the two different construction sites and the end of initial driving(EOID) were also performed and then restrike tests were performed after certain time lag. The H-pile, pipe pile, PHC pile are installed by driving into the loose silty soil and then restrike tests were performed. Nine days after pile driving, the bearing capacity of H and pipe pile were increased whereas there is not bearing capacity increasement with PHC pile. When the dense silty soil, the restrike test results showed that the bearing capacity of H and pipe pile increased up to 1.17 times. The 1-st and 2-nd restrike tests performed after 6 and 12 day, respectively. The results showed that the bearing capacity of PHC pile was decreased but the bearing capacity of piles were increased up to 1.38 times after 13 days with the third restrike test.

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A Numerical Investigation on End Bearing Capacity of Single Pile Installed in Fractured Rock Mass (절리암반에 설치된 단말뚝기초의 선단지지력에 관한 수치해석 연구)

  • Kim, Tae-Jung;Yoo, Chung-Sik
    • Journal of the Korean Geotechnical Society
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    • v.29 no.1
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    • pp.61-70
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    • 2013
  • This paper presents the results of a two-dimensional finite element analysis of end bearing capacity of single pile installed in fractured rock mass. A number of cases were analyzed using Hoek-Brown criterion that can consider the condition of rock joints. Considering a wide range of joint conditions in which the pile is embedded into the rock, GSI was set as a main parameter. And the effects of pile diameter, unconfined compressive strength of rock and Hoek-Brown constant $m_0$ were considered. Based on parameter study, end bearing load factor graphs were suggested.

The Estimation of Bearing Capacity of Auger-drilled Pile in Sand-Gravel by Dynamic Load Test (동재하시험에 의한 모래자갈층에 근입된 매입말뚝의 지지력 산정)

  • Choi, Ki-Chul;Moon, Yu-Ho;Oh, Won-Keun;Chun, Byung-Sik
    • 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.

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A Study on Bearing Capacity Evaluation Method of Surface Reinforcement Method for Soft Ground in Consideration of Stiffness (강성도를 고려한 연약지반 표층처리공법 지지력산정방법에 관한 연구)

  • Ham, Tae-Gew;Seo, Se-Gwan;Cho, Sam-Deok;Yang, Kee-Sok;You, Seung-Kyong
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.1118-1125
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    • 2009
  • This study, as basic research which was intended to develope the surface reinforcement method using reinforcement material which is applicable to very soft ground in Korea, was aimed at proposing Bearing Capacity Evaluation method for the surface ground improvement method. To that end, a wide width tensile test using geotextile, geogrid and steel bar (substitute for bamboo) and 21 kinds of the laboratory model tests with the end restraint conditions of the reinforcement that comprises the constrained and partially constrained (3 types) conditions were conducted. According to result of tests, Terzaghi's bearing capacity method is adequate to calculate bearing capacity in non-stiff material(geotextile, geogrid). But, It can't adequate to stiff material(bamboo net). So, New bearing capacity method suggest surface reinforcement method of very soft ground which Terzaghi's bearing capacity method modify for effect of stiffness.

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Evaluation on Bearing Capacity of End Girder Member with Local Corrosion (지점부 부재의 부식손상에 따른 강거더 단부 지압강도 평가)

  • Ahn, Jin Hee;Lee, Won Hong;Kim, In Tae;Jeong, Young Soo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.5
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    • pp.74-82
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    • 2017
  • Localized corrosions damages in their structural sections can be occurred affected by installed environment conditions with high temperature as near the coastline and humidity or their poor maintenance situation. In bearing supports of steel bridges, especially, lower web and vertical stiffener in end girder support can be easily corroded because of relatively higher humidity due to the narrow space in the end of girder and the wetted accumulated sediments affected by rain water or antifreezing admixture leaked from expansion joint. It can be related to change in their structural performance. In this study, thus, bearing strength test specimens were fabricated considering corrosion damage in the web and vertical stiffeners and the change in their bearing strengths were experimentally evaluated. From the test results, localized corrosion damage of structural members in the end girder affected the bearing strength of end girder support, especially, localized corrosion damage of the vertical stiffener relatively highly affected their bearing strengths.

A Study on the Utilization of PG-Pile in waste landfill (폐기물 매립지반에서의 PG Pile의 적용성에 관한 연구)

  • 천병식;최춘식
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.11a
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    • pp.419-426
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    • 2000
  • Waste landfill consists of cover layer, glass, robber, sheet, food waste, etc and is in very loose state. So, the proper method must be applied to ground improvement of waste landfill according to its characteristics and conditions. In this paper, analysis for field tests as static loading test, bearing capacity test were peformed. In result, PG pile method proved to be effective and economic, because it affected increase of end bearing capacity, the prevention of differential settlement and over 20% increase of density by expansion of pile.

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A Study on the Utilization of PG-Pile in Waste Landfill (폐기물 매립지반에서의 PG Pile의 적용성에 관한 연구)

  • 천병식;최춘식
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2000.10a
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    • pp.135-139
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    • 2000
  • Waste landfill consists of cover layer, glass, robber, sheet, food waste, etc and is in very loose state. So, the proper method must be applied to ground improvement of waste landfill according to its characteristics and conditions. In this paper, analysis for field tests as static loading test, bearing capacity test were performed. In result, PG pile method proved to be effective and economic, because it affected increase of end bearing capacity, the prevention of differential settlement and over 20% increase of density by expansion of pile.

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