• Title/Summary/Keyword: pile capacity

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Bearing Capacity Study for Small-Scale Testing of Rotary Pile with Helix Plate (축소모형 로타리 파일의 나선날개에 따른 지지성능에 관한 연구)

  • Shin, Eun-Chul;Kim, Kyeong-Sig;Moon, Hyeong-Rok
    • Journal of the Korean Geosynthetics Society
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    • v.15 no.1
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    • pp.37-46
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    • 2016
  • Rotary pile consists a single or multiple helix plate and it is installed into the ground using the rotation of the helix plate. Rotary pile in soft ground is able to be supported by pile shaft and helix plate. When the pile is installed into hard layer relatively, the end bearing capacity is possible to be increased by the lower helix plate. In this paper, small-size rotary piles were manufactured with using steel pipe which is reduced to 1/5 size of the rotary pile on the construction field. Pile load test was carried out on the foundation soil which was formed by weathered soft soil. The bearing capacity of small-scale piles depends on the number of helix plate, the length of plate diameter, and an interval of plates, respectively. The bearing capacity of pile increases about 40% with 3 helix plate and it is also confirmed that the bearing capacity is improved about 10% as the increment of plate interval.

The effect of group pile installation (무리말뚝 시공의 영향)

  • Lee, Myung-Whan;Hong, Hun-Sung;Kim, Sung-Hoi;Jun, Young-Suk
    • 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.

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A Study on the Loading Capacity Standard of Bi-directional Pile Load Test (BD PLT) (양방향말뚝재하시험의 재하용량 기준에 관한 연구)

  • Choi, Yongkyu
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.6C
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    • pp.379-388
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    • 2008
  • In the bi-directional pile load test (BD PLT) for pile load tests of Mega pile foundations, loading capacity standard is not specified exactly. Therefore there are so many confusions in performing the BD PLT and variations up to maximum 2 times in loading capacity are come out. In this study, standards of bi-directional pile load test (BD PLT) were considered. Based on cases of the bi-directional pile load test performed in domestic areas, maximum equivalent test load, test load increasing ratio, loading capacity increasing ratio and sufficiency ratio of design load were analyzed. It could be known that the loading capacity standard of bi-directional pile load test must be defined as 1-directional loading capacity and also must be established as more than 2 times of design load.

Characteristics of Settlement and Bearing Capacity of Soft Ground Improved by Granular Pile (Granular Pile에 의해 개량된 연약지반의 지지력 및 침하특성)

  • 천병식;여유현
    • Proceedings of the KSR Conference
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    • 2002.05a
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    • pp.289-294
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    • 2002
  • Sand Compaction Pile (SCP) method, which uses sand material, is frequently used in Korea. However, the use of sand for SCP faces environmental and economical problems with the shortage of its resources. Therefore, it is necessary to substitute other materials for compaction piles. One of the alternatives is using gravel in lieu of sand. Granular Pile, constituted with sand and crushed-stone, is one of the methods to improve soft clay and loose sandy ground. In this study, modeled pile load tests are performed in test cell. The observations are made on the consolidation and the variation of water table of three different grounds, original, sand pile installed, and granular pile installed ground. In addition, engineering characteristics such as bearing capacity, settlement and drainage are investigated. The test results show that Gravel Compaction Pile (GCP) is more efficient for increasing bearing capacity and reducing settlement than SCP and had similar pore water pressure dissipation to sand. Therefore, the results show that GCP can be a good substitution for SCP.

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Centrifuge Model Experiments on Behaviors of Single Pile (단말뚝 거동에 관한 원심모형실험)

  • Yoo, Nam-Jae;Lee, Myeung-Woog;Lee, Jong-Ho
    • Journal of Industrial Technology
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    • v.17
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    • pp.111-118
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    • 1997
  • This thesis is an experimental research of investigating behavior of single pile, subjected to the vertical compression loads, using the centrifuge facility located in the geotechnical engineering laboratory in Kangwon National University. Centrifugal model experiments of model pile were carried out changing diameter of model pile, relative density of sandy ground and the gravitational level applied in the centrifuge. Thus, their effects on the load-settlement behavior and the ultimate bearing capacity of pile were investigated. Experimental results obtained from centrifuge model tests were compared with the theoretical or semi-empirical equations to analyze values of ultimate bearing capacity of model pile. When we compare the ultimate bearing capacity of experimental results with the ultimate bearing capacity of theorical results, the experimental results appear more higher in the De Beer method and Meyerhof. Expecially, Terzaghi method is very same as the experimental results normally.

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Reinforcement for Bearing Capacity of PRD Steel Pile at Mudstone Area (이암지역에 근입된 PRD강관말뚝의 지지력 보강)

  • Kong, Jin-Young;Kang, Hee-Jin;Chun, Byung-Sik
    • Proceedings of the KSR Conference
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    • 2007.05a
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    • pp.1760-1769
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    • 2007
  • The cut slope sliding which has been frequently encountered in Pohang area has been reported due to the rapid reduction of shear strength in mudstone after being exposed to the air. Mudstone has characteristics that it has high enough strength and stiffness in a dry condition, but the strength and stiffness decrease in a wet condition with groundwater infiltration. The case study in this paper shows that mudstone which had enough strength in a boring stage has lost the strength after installing PRD steel pipe pile inducing an insufficient bearing capacity, which has been ascertained by the static load test. Test construction has been performed to investigate the most favorable method for increasing a pile bearing capacity in mudstone with various methods such as MSG (Micro Silica Grouting) around the tip and side of a pile, the perimeter grouting combined with Micro pile reinforcement, and concrete filling after tip reinforcing grouting. From the test construction, MSG has been turned out to be the most favorable method for increasing a pile bearing capacity in mudstone, which has been confirmed by the static load test.

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Computational intelligence models for predicting the frictional resistance of driven pile foundations in cold regions

  • Shiguan Chen;Huimei Zhang;Kseniya I. Zykova;Hamed Gholizadeh Touchaei;Chao Yuan;Hossein Moayedi;Binh Nguyen Le
    • Computers and Concrete
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    • v.32 no.2
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    • pp.217-232
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    • 2023
  • Numerous studies have been performed on the behavior of pile foundations in cold regions. This study first attempted to employ artificial neural networks (ANN) to predict pile-bearing capacity focusing on pile data recorded primarily on cold regions. As the ANN technique has disadvantages such as finding global minima or slower convergence rates, this study in the second phase deals with the development of an ANN-based predictive model improved with an Elephant herding optimizer (EHO), Dragonfly Algorithm (DA), Genetic Algorithm (GA), and Evolution Strategy (ES) methods for predicting the piles' bearing capacity. The network inputs included the pile geometrical features, pile area (m2), pile length (m), internal friction angle along the pile body and pile tip (Ø°), and effective vertical stress. The MLP model pile's output was the ultimate bearing capacity. A sensitivity analysis was performed to determine the optimum parameters to select the best predictive model. A trial-and-error technique was also used to find the optimum network architecture and the number of hidden nodes. According to the results, there is a good consistency between the pile-bearing DA-MLP-predicted capacities and the measured bearing capacities. Based on the R2 and determination coefficient as 0.90364 and 0.8643 for testing and training datasets, respectively, it is suggested that the DA-MLP model can be effectively implemented with higher reliability, efficiency, and practicability to predict the bearing capacity of piles.

Bearing capacity at the pile tip embedded in rock depending on the shape factor and the flow

  • Ana S. Alencar;Ruben A. Galindo;Miguel A. Millan
    • Computers and Concrete
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    • v.31 no.5
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    • pp.443-455
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    • 2023
  • This is a research analyses on the bearing capacity at a pile tip embedded in rock. The aim is to propose a shape coefficient for an analytical solution and to investigate the influence of the plastic flow law on the problem. For this purpose, the finite difference method is used to analyze the bearing capacity of various types and states of rock masses, assuming the Hoek & Brown failure criterion, by considering both plane strain and an axisymmetric model. Different geometrical configurations were adopted for this analysis. First, the axisymmetric numerical results were compared with those obtained from the plane strain analytical solution. Then the pile shape influence on the bearing capacity was studied. A shape factor is now proposed. Furthermore, an evaluation was done on the influence of the plastic flow law on the pile tip bearing capacity. Associative flow and non-associative flow with null dilatancy were considered, resulting in a proposed correlation. A total of 324 cases were simulated, performing a sensitivity analysis on the results and using the graphic output of vertical displacement and maximum principal stress to understand how the failure mechanism occurs in the numerical model.

Behavior of Axial Load Transfer for Open-ended Steel Pipe Pile in Alluvial Deposits (하상퇴적토층에 관입된 개단강관말뚝의 축하중 전이 거동)

  • 김상현;성인출;정창규;김명학;최용규
    • Proceedings of the Korean Geotechical Society Conference
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    • 2001.03a
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    • pp.283-290
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    • 2001
  • In this study, static Pile load tests and PDA for open-ended steel pipe pile($\phi$ = 609.6 mm, t = 14 mm) penetrated into the gravel layer(GP - GM) was accomplished and axial load distribution was measured. Based on the tests results, the ultimate bearing capacity and axial load bearing mode were examined. Also, the ultimate pile capacity was calculated by APIL $E^{PLUS}$./.

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