• Title/Summary/Keyword: Allowable Bearing Capacity

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An Experimental Study on Bearing Capacity of Drilled Shaft with Mid-size (중구경 현장타설말뚝의 지지력 특성에 관한 실험적 연구)

  • Lee, Kwang-Wu;You, Seung-Kyong;Park, Jeong-Jun;Yun, Jung-Mann;Hong, Gigwon
    • Journal of the Korean Geosynthetics Society
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    • v.18 no.4
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    • pp.263-272
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    • 2019
  • This paper describes the results of bearing capacity using field loading test of pile, in order to extend the applicability of drilled shaft with mid-size, and the results were compared with the prediction results of design bearing capacity by empirical formular. The static load test result showed that the allowable bearing capacity of high pile strength was about 2.4 times higher than that of low pile strength. The dynamic load test result showed that the allowable bearing capacity of high pile strength was about 1.4 times~1.5 times higher than that of low pile strength. The comparison result of allowable bearing capacity between static and dynamic load test showed that the difference of allowable load ranged from 3% to 6% under the same settlement conditions. As a result of comparing the ultimate bearing capacity by load test and design bearing capacity, it was found that the FHWA proposed equation could be more reasonable than the other proposed equation in load sharing ratios of end bearing and skin friction.

Evaluation of the Structural Stability of Rammed Earth Construction :The Case Restoration Project of the Stone Pagoda at Mireuksa Temple Site in Iksan

  • Min, Hwang-Sik;Choen, Deuk-Youm
    • Architectural research
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    • v.20 no.3
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    • pp.65-73
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    • 2018
  • The restoration of foundations supporting the immense load of the stone pagoda at Mireuksa Temple Site prioritizes securing its structural stability. But so far, rammed earth construction is still not easy to determine the structural stability. This paper aims to emphasize that a scientific experimental study was conducted on a rammed earth construction, to identify its methodology and obtain objective data about structural stability of the foundation work. An experimental study fabricated specimens from the soil that had been removed during the excavation survey, determined the allowable bearing capacity through plate load tests, and compared the results with the predicted stress after reassembly of the stone pagoda to estimate the structural stability. Then, the repair method was selected based on the experimental study result. The evaluation method of the restoration of foundations consisted of an examination of the allowable bearing capacity and settlement. The allowable bearing of the reinforced foundation was more than twice the contact pressure under the stacked stones of the pagoda. The possibility of settlement of the rammed earth foundation soil layer during the pagoda assembly is expected to be very low because the settlement amount of the reformed soil layer is less than half of the settlement of the stabilized existing soil layer.

Settlement and Bearing Capacity of Roadbed Subjected to Tilting-train Loading in Various Ground Conditions

  • Jeon, Sang-Soo
    • International Journal of Railway
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    • v.8 no.2
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    • pp.35-41
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    • 2015
  • Tilting-train is very attractive to the railroad users in the world due to the advantage of high speed in curved track using pre-existing infrastructure of railway. Tilting-train has a unique allowable speed and mechanism especially in curved track. In this work, when tilting-train is operated with the allowable speed, the behavior of roadbed is evaluated by examining its settlement and bearing capacity. Additionally, the stability of roadbed is estimated as the roadbed is in the condition of soft soil influenced by the weather effects and cyclic train loading. Numerical results show that the roadbed settlement satisfies the allowable settlement when the elastic modulus of upper roadbed should be greater than $5000t/m^2$.

Characteristics of Bearing Capacity and Reliability-based Evaluation of Pile-Driving Formulas for H Pile (H-pile의 지지력 특성 및 동역학적 공식의 신뢰도 평가)

  • 오세욱;이준대
    • Journal of the Korean Society of Safety
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    • v.18 no.1
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    • pp.81-88
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    • 2003
  • Recently, pile foundations were constructed in rough or soft ground than ground of well condition thus it is important that prediction of ultimate bearing capacity and calculation of proper safety factor applied pile foundation design. This study were performed to dynamic loading tests for the thirty two piles at four different construction sites and selected pile at three site were performed to static loading tests and then compare with measured value and value of static and dynamic loading tests. The load-settlement curve form the dynamic loading tests by CAPWAP was very similar to the results obtained from the static load tests. Based on dynamic and static loading tests, the reliability of pile-driving formula were analyzed and then suggested with proper safety factor for prediction of allowable bearing capacity in this paper.

A Comparative Study on the Evaluation of Bearing Capacity for Driven Pile in Static Load Test (현장정재하시험 결과를 통한 타입말뚝 지지력 판정법 비교 연구)

  • Chun, Byung-Sik;Seo, Deok-Dong;Choi, Heon-Kil;Yoon, Hwan-Ho
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.677-686
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    • 2005
  • The allowable bearing capacity of a pile, the most important factor in stability estimation, is determined by applying safety factor to the ultimate load or yield load. There are several but contradictory methods available in current design codes to estimate the allowable bearing capacity and the safety factor. This paper analyzes load-settlement curves obtained from 19 static load tests measured from 11 sites. At all tests, the load is applied until apparent failure is observed. The validity of the ultimate and yield load estimation method and load caculated from the settlement criterion is investigated through comparison with the measured data. In addition, a new procedure to estimate allowable load and safety factor is proposed. Additional data from field static load tests, such as those incorporated in this study, are needed to more reliably apply the proposed method in design practice.

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A Comparison of Bearing Capacity Equations for a Single Pile Considering Negative Skin Friction (부주면마찰력을 고려한 단말뚝의 허용지지력 공식 분석)

  • Lee, Sung-June;Jeong, Sang-Seom;Ko, Jun-Young
    • Journal of the Korean Geotechnical Society
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    • v.26 no.8
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    • pp.27-37
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    • 2010
  • Downdrag force develops when a pile is driven through a soil layer which will settle more than a pile. There is no obvious criterion for application of the current pile design method considering the negative skin friction. Therefore, in this study, numerical analyses were performed to investigate the behavior of a single pile subjected to negative skin friction and their results were used to determine the applicability of the current design method. Including three different sites in Song-do area and two different cases with friction pile and end bearing pile conditions, total six cases were considered. The load-settlement relationships and the neutral points were estimated for different end bearing conditions and the allowable bearing capacity of piles with negative skin friction was investigated through parametric studies. Based on the results showed that the negative skin friction made a major influence on the settlement of a pile and its stress. However the allowable bearing capacity may not be influenced by the negative skin friction. Compared with the allowable bearing capacity obtained from the ultimate bearing capacity with the safety factor of 3, the current design method with the safety factor of 3 underestimated the allowable bearing capacities regardless of the end bearing conditions. On the other hand, the current design method with the safety factor of 2 yielded reasonable results depending on the end bearing conditions.

A Study on the Bearing Strength of Steel Fiber Reinforced Concrete (강섬유보강 콘크리트의 지압강도에 관한 연구)

  • 차희석;조환성
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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    • pp.111-114
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    • 1999
  • SFRC(Steel Fiber Reinforced Concrete) has advantage of crack resistance and ductility failure behavior. But the study which investigated about effect of steel fiber under bearing stress is not to be enough, and it does not be sure of criterion of SFRC for allowable bearing stress formula in internal specification. The purpose of this study is to clear the influence of SFRC on the bearing capacity and ductility of material through static loading test. additionally, arrive an allowable bearing stress formula for SFRC and examine mechanical behaviro by the 3-D finite element analysis.

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The study on the bearing capacity and settlement of a foundation placed over a tunnel (Tunnel 상부지반의 기초 지지력과 침하에 관한 연구)

  • 김수삼;정승용;김용수;권태창
    • Journal of the Korean Society for Railway
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    • v.2 no.4
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    • pp.20-31
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    • 1999
  • When a foundation on the ground with tunnel is constructed, the ultimate bearing capacity of a footing is reduced by tunnel. In practice, structure may bate a considerable damage because of large settlement. This study shows that the settlement which is caused by variety of the ultimated bearing capacity leads fatal damages to the footing above tunnel. Therefore, it is necessary to study on the reduction both of the ultimate bearing capacity which leads a failure and of tolerable settlement which satisfies the safety of the building. For this reason, the variety of ultimated bearing capacity was analyzed using tub-dimensional elasto-plastic finite difference method in this paper. As a result, bearing capacity of the foundation above tunnel should be determined after establishing limit of allowable settlement and considering reduction-ratio of bearing capacity.

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The Behavior of Bearing Capacity for the Precast files (기성말뚝의 지지거동)

  • 박영호
    • Journal of the Korean Geotechnical Society
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    • v.16 no.1
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    • pp.107-116
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    • 2000
  • Dynamic and static load tests are conducted in four construction sites by using steel pipe piles(SPP) and concrete piles to compare differences of load bearing mechanism. Steel pipe piles are instrumented with electric strain gages and are subject to dynamic load tests during driving. The damage of strain gages attached is checked simultaneously. Static load test is also conducted on the same piles after two to seven days' elapse. Then load-settlement behavior and shaft and/or tip resistances are measured. As a result, the allowable bearing capacity calculated by the Davisson's offset method of CAPWAP analysis shows 2~33% larger than that of static load test. The average value of allowable bearing capacity of static load test is closer to the allowable capacity obtained at the safety factor of 2.5 applied on ultimate bearing capacity than to the one obtained from the Davisson's offset method. The analysis of strain gage readings shows that unit skin friction increases with depth. Furthermore, the friction mobilized around the 1~2m above the pile tip considerably contributes to the total shaft resistance.

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