• Title/Summary/Keyword: 지지력 예측

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Effect of Configuration of Shaft and Helix Plate on Bearing Capacity of Moderate-size Helical Pile : II. Bearing Capacity Prediction (중소구경 헬리컬 파일의 축과 원판의 형상이 지지력에 미치는 영향 평가 : II. 이론식과 토크에 의한 지지력 예측 비교)

  • Lee, Jongwon;Lee, Dongseop;Na, Kyunguk;Choi, Hangseok
    • Journal of the Korean Geosynthetics Society
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    • v.13 no.2
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    • pp.41-47
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    • 2014
  • Various prediction methods for the bearing capacity of helical piles have been introduced with consideration of both the steel shaft and the helix plates attached to the shaft. In this paper, three representative methods, that is, individual bearing method, cylindrical shear method, and torque correlation method are discussed and compared to each other. The prediction methods were verified by comparing with a series of loading test results performed on moderate-size helical piles from the companion paper. As a result, the measured bearing capacity is greater than the bearing capacity predicted by the cylindrical shear method, but smaller than that of the individual bearing method. In addition, the bearing capacity predicted by the torque correlation method is in good agreement with the measured bearing capacity.

Prediction of Ultimate Bearing Capacity of Soft Soils Reinforced by Gravel Compaction Pile Using Multiple Regression Analysis and Artificial Neural Network (다중회귀분석 및 인공신경망을 이용한 자갈다짐말뚝 개량지반의 극한 지지력 예측)

  • Bong, Tae-Ho;Kim, Byoung-Il
    • Journal of the Korean Geotechnical Society
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    • v.33 no.6
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    • pp.27-36
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    • 2017
  • Gravel compaction pile method has been widely used to improve the soft ground on the land or sea as one of the soft ground improvement technique. The ultimate bearing capacity of the ground reinforced by gravel compaction piles is affected by the soil strength, the replacement ratio of pile, construction conditions, and so on, and various prediction equations have been proposed to predict this. However, the prediction of the ultimate bearing capacity using the existing models has a very large error and variation, and it is not suitable for practical design. In this study, multiple regression analysis was performed using field loading test results to predict the ultimate bearing capacity of ground reinforced by gravel compaction pile, and the most efficient input variables are selected through evaluation of error by leave one out cross validation, and a multiple regression equation for the prediction of ultimate bearing capacity was proposed. In addition, the prediction error was evaluated by applying artificial neural network using the selected input variables, and the results were compared with those of the existing model.

Bearing Capacity Characteristics of Stone Column by Numerical Analysis (수치해석에 의한 쇄석기둥의 지지력 특성)

  • Chun, Byung-Sik;Kim, Baek-Young
    • Journal of the Korean GEO-environmental Society
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    • v.5 no.1
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    • pp.75-84
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    • 2004
  • Stone column is one of the soft ground improvement method, which can enhance ground conditions such as the settlement reduction and the increasement of bearing capacity with applying the crushed stone instead of sand. In recent, general construction material, sand is in short of supply. Therefore, the bearing capacity improvement by the stone column is considered as the alternative method needed in many cases so the bearing capacity estimation is considered as important point. Nevertheless, adequate estimation methods to predict bearing capacity of stone column considering stone column and improvement effect of ground is not yet prepared. For the analysis of above mentioned points, the behavior of stone column were simulated as numerically on various property cases of crushed stone and surrounded ground. Through the numerical analysis of simulation results, the formula for the bearing capacity estimation of stone column was suggested. This formula was verified by comparing the prediction result of in situ test.

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A Study on Optimized Artificial Neural Network Model for the Prediction of Bearing Capacity of Driven Piles (항타말뚝의 지지력 예측을 위한 최적의 인공신경망모델에 관한 연구)

  • Park Hyun-Il;Seok Jeong-Woo;Hwang Dae-Jin;Cho Chun-Whan
    • Journal of the Korean Geotechnical Society
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    • v.22 no.6
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    • pp.15-26
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    • 2006
  • Although numerous investigations have been performed over the years to predict the behavior and bearing capacity of piles, the mechanisms are not yet entirely understood. The prediction of bearing capacity is a difficult task, because large numbers of factors affect the capacity and also have complex relationship one another. Therefore, it is extremely difficult to search the essential factors among many factors, which are related with ground condition, pile type, driving condition and others, and then appropriately consider complicated relationship among the searched factors. The present paper describes the application of Artificial Neural Network (ANN) in predicting the capacity including its components at the tip and along the shaft from dynamic load test of the driven piles. Firstly, the effect of each factor on the value of bearing capacity is investigated on the basis of sensitivity analysis using ANN modeling. Secondly, the authors use the design methodology composed of ANN and genetic algorithm (GA) to find optimal neural network model to predict the bearing capacity. The authors allow this methodology to find the appropriate combination of input parameters, the number of hidden units and the transfer structure among the input, the hidden and the out layers. The results of this study indicate that the neural network model serves as a reliable and simple predictive tool for the bearing capacity of driven piles.

Prediction on Ultimate Vertical and Horizontal Bearing Capacity of Steel Pipe Piles by Means of PAR (PAR에 의한 강관 말뚝의 극한 수직 및 수평 지지력 예측)

  • 최용규
    • Geotechnical Engineering
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    • v.13 no.4
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    • pp.13-24
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    • 1997
  • A predicting method for ultimate vertical and horizontal bearing capacity by means of PAR(Pile Analysis Routines) was suggested. Based on the static pile load test data, case studies by means of PAR were performed. Ultimate pile capacity predicted by PAR was within 15% error range of that determined by stairs pile load tests. Also, the results of static pile load test, statnamic tests and PDA data performed on pipe piles were compared and, by using PAR, ultimate pile capacity was determined. Distributions of atrial pile load could be predicted and load transfer analysis could be done approximately by those distributions.

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Evaluation of Point Bearing Capacity using Field Model Pile Test (현장 축소모형 말뚝 시험을 이용한 선단지지력 예측)

  • Lee, Chang-Ho;Lee, Woo-Jin;Jeong, Hun-Jun;Han, Shin-In
    • Journal of the Korean GEO-environmental Society
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    • v.6 no.3
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    • pp.47-54
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    • 2005
  • In many practical cases, design methods of pile have been used mainly semi empirical bearing capacity equations. It can be done that confirmation of pile bearing capacities through using of dynamic and static tests during constructing or after constructions. If a prediction of layered point pile bearing capacity could be done through simple tests during field investigation, it could be done that more reliable design of pile than a prediction of using semi empirical equations or static formulations. This paper suggests a method to estimated point bearing capacity during in-situ investigation by using the dynamic rod model pile and verifies the point bearing capacity compare with results of static pile load tests. From test results, the unit ultimate point bearing capacities are relatively similar through a dynamic rod model pile tests and static pile load tests. The unit ultimate point bearing capacity by using N value is shown about 50 % value of measured unit ultimate point bearing capacity from field test result and the prediction of the unit ultimate point bearing capacity by using N value is shown very conservative, illogical and uneconomical pile designs.

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Assessment of Design Criteria for Bearing Capacity of Rock Socketed Drilled Shaft (암반에 근입된 현장타설말뚝의 지지력 산정기준에 대한 평가)

  • 백규호;사공명
    • Journal of the Korean Geotechnical Society
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    • v.19 no.4
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    • pp.95-105
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    • 2003
  • The existing design criteria f3r the estimation of ultimate bearing capacity of drilled shaft socketed into rock masses are mainly obtained from the ultimate pile load capacities, which are determined by inconsistent failure criteria. Therefore, these design criteria generally produce difffrent predictions even for drilled shaft in the same condition. In this paper, the accuracies of the existing design criteria are investigated to develop an optimized design process for drilled shaft socketed into rock masses. Reasonable and consistent ultimate capacities of drilled shafts socked into rock masses, necessary far the check of accuracies of predictions, are determined by applying a specific failure criterion to a total of 11 pile load test results. A comparison between the predicted and the measured load capacities shows that ultimate base load capacities calculated from Zhang and Einstein's equation and NAVFAC are close to the measured values. Rosenberg and Journeaux's equation produces satisfactory prediction f3r ultimate side load capacity.

Estimation of Ultimate Bearing Capacity of SCP and GCP Reinforced Clay for Laboratory Load Test Data (SCP 및 GCP 개량 점성토지반의 실내재하시험에 대한 극한지지력 산정 방법 개발)

  • Bong, Tae-Ho;Kim, Byoung-Il;Han, Jin-Tae
    • Journal of the Korean Geotechnical Society
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    • v.34 no.6
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    • pp.37-47
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    • 2018
  • In this study, 34 laboratory load test data were collected, and analyzed to propose the equations for predicting ultimate bearing capacity of sand compaction pile (SCP) and gravel compaction pile (GCP) reinforced clay. The collected data were compared with the ultimate bearing capacity estimated by existing theoretical equations, and the prediction accuracy of the existing theoretical equations was identified. Also, multiple regression analysis was performed to predict the ultimate bearing capacity, and the most efficient number and type of input variables were selected through error evaluation by leave-one-out cross validation. Finally, the multiple regression equations for estimating the ultimate bearing capacity of laboratory load test for SCP and GCP were proposed, and their performance was evaluated.

Reliability Based Pile Bearing Capacity Evaluation (신뢰도에 근거한 말뚝의 지지력 평가)

  • Lee, In-Mo;Jo, Guk-Hwan;Lee, Jeong-Hak
    • Geotechnical Engineering
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    • v.11 no.1
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    • pp.9-22
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    • 1995
  • The purpose of this study is to propose safety factors of pile bearing capacity based on the reliability analysis. Each prediction method involves various degrees of uncertainties. To account for these uncertainties in a systematic way, the ratios of the measured bearing capacity from pile load tests to the predicted bearing capacity are represented in the form of a probability density function. The safety factor for each design method is obtained so that the probability of pile foundation failure is less than 10-3. The Bayesian theorem is applied in a way that the distribution using static formulae is assumed to be the A-prior and the distribution using dynamic formulae or wave equation based methods is assumed to be the likelihood, and these two are combined to obtain the posterior which has the reduced uncertainty. The results of this study show that static formulae of the pile bearing capacity using the 5.p.7. N-value as well as dynamic formulae are highly unreliable and have to have the safety factor more than 7.4 : the wave equation analysis using PDA(Pile Driving Analyzer) system the most reliable with the safety factor close to 2.7. The safety factor could be reduced certain amount by adoption the Bayes methodology in pile design.

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Study on the Bearing Capacity of Helical Pile through Field Load Tests (현장재하시험을 통한 헬리컬파일의 지지력에 관한 연구)

  • Kwon, Gi-Ryeol;Jang, Jeong-Wook;Cho, Song-Hyun
    • The Journal of the Korea Contents Association
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    • v.20 no.11
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    • pp.669-675
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    • 2020
  • This research has focused on comparing the capacity predicted by the theoretical formula with the one measured by field load tests to examine characteristics of the bearing capacity of a helical pile. The helical pile is featured by a central shaft with one or more helical-shaped bearing plates. Being established by a small rotary attached to an excavator that applies toque, the helical piles can be readily constructed at narrow sites, especially in an urban area with relatively less noise than the others requiring driving and excavation. Although many cases of the helical pile constructions can be recently found, the bearing capacity of the pile has been limitedly studied. To this end, this contribution analyzes and presents comprehensive results of the ten field loading tests with an application of different parameters depending on joint condition and specification of the helical piles, and types of tests and grouting.