Bearing Capacity Of Pipe Pile Research Articles

Analysis of the behaviour of the floating pipe pile foundation on soft soil

Planning the foundation according to the characteristics of the soil is the most important thing before starting construction. In recent studies, the use of PVC pipe pile foundations has been introduced. These foundations, called floating foundations, offer a lighter and more economical solution for simple buildings on soft soils. The study involved variations in pipe diameters of consistent lengths. In laboratoryscale axial loading tests, the behaviour of pipe stacks against load drop is observed. The bearing capacity of pipe piles is evaluated through a static loading test, with one end of the pipe pile hermetically sealed and aspirated in an alternating pile in a glass box filled with soft soil with a content of 98%. The results of this test are then analyzed with the Chin Method Interpretation to determine the carrying capacity and behaviour of pipe piles against soft soil, The results of the analysis show that the diameter of the pipe piles has a significant effect on the bearing capacity of the foundation. Although the results are promising, further research is still needed, especially in the development of foundation construction suitable for multi-storey buildings in areas with soft soil or peat

Experimental Study on Load-Carrying Behavior of Large Open-Ended Pipe Pile in Cohesionless Soils

Large-diameter open-ended pipe piles typically refer to pipe piles with diameters larger than 0.91 m. These piles, when properly designed and constructed, could provide high load-carrying capacity against axial loading, uplift, and overturning in the offshore environment. The current American Association of State Highway and Transportation Officials (AASHTO) specification for pipe piles is based on the database collected from piles with diameters less than 0.61 m and is, therefore, insufficient for the design of large-diameter open-ended pipe piles. This paper introduces an experimental program to investigate the static load-carrying behavior of open-ended pipe piles. Two types of restriction plates, i.e., one-hole plate and four-hole plate, were designed and installed inside the pipe to study their influence on the loading bearing behavior. Beside the laboratory-scale pile experiments, the testing program was augmented with geotechnical centrifuge experiments, which upscale the dimensions of model piles close to the size used at the field scale. The combined laboratory and geotechnical centrifuge experiments help to analyze the load-carrying behavior of pipe piles with different pile diameters, types of restriction plate, and embedment depths. The experimental results indicate that the formation of a soil plug is crucial to mobilize the bearing capacity of pipe piles. The restriction plate helps to form the soil plugging, which leads to a higher end bearing capacity. The selection of types of restriction plate should be determined on a case-by-case basis with considerations of mechanical performance and pile drivability.

End bearing response of open-ended pipe piles embedded in rock

Prediction of bearing capacity of steel pipe piles in rock masses is an important consideration in civil engineering especially as such prediction influences the safety of the supported superstructures as well as the pile integrity in pile driving operations. Provided that the rock mass is described as a linear elastic and perfectly plastic material obeying the Hoek-Brown failure criterion, a finite element analysis is performed to investigate the embedment depth effect on the annular base bearing capacity and the failure mechanism of typical open-ended pipe piles in sedimentary rock masses. The pipe pile has smooth walls and rough toe surface. Annular toe resistance of pipe piles can serve as an estimate of the rock mass resistance to driving in a fully coring mode which is usually expected for large diameter open-ended pipe piles. Pipe pile results are also extended to circular piles and embedded strip foundations socketed in rock masses. The analysis is shown to highlight the influence of the annular geometry of the pipe pile causing an unsymmetrical failure mechanism with respect to pipe wall center as well as an inclination of rock mass reaction, which if sufficiently large, may lead to pile convergence and damage during pile driving operations. The failure mechanism legitimates the plug tendency to rise up in the pipe and explains the plug formation. The study demonstrates that in most practical applications, the bearing capacity of pipe piles approaches a limiting value, which is less than or at most equal to the end bearing capacity of an embedded strip foundation of width equal to the pipe wall thickness. A comparison has been made with experimental data. It is shown that the results are relatively in good agreement with test data in terms of rock mass resistance and the mechanism of rock plug formation.

Reliability assessment on prediction of pile bearing capacity

There are many prediction methods that can be used to determine the bearing capacity of pipe pile. However, most of these methods are highly sensitive to specific in situ conditions and hence usually result in significant error. Therefore, it is important to evaluate the reliability of different pile bearing capacity prediction methods. Based on reliability theory, a computer code is developed in this paper to calculate reliability. Random variable statistic properties and corresponding reliabilities for different prediction methods are investigated and analysed. Results show that the reliability index for logarithmic normal distribution is higher than normal distribution. Analysis results demonstrate that the checking point method (JC method) method has a slightly lower efficiency than the Monte-Carlo importance sampling method and the Monte-Carlo direct sampling method. The Monte-Carlo importance sampling method has a higher efficiency than the Monte-Carlo direct sampling method. The Monte-Carlo importance sampling method can be used in major engineering projects. It is concluded that the clustering centre method has higher reliability in predicting pile bearing capacity than the Eslami and Fellenius method, Almeida method and Powell method.

Time Effect of the Pile Bearing Capacity in Dredger Fill

The dissipating of pore water pressure caused by pile sinking is one of the main factors resulting in time effect of ultimate bearing capacity of pile.The pore water pressure is monitored at each observing point during pile sinking and after that. With the pore pressure plan embedded in advance, by means of spot test in the process of pile sinking, under this geological conditions of the pile foundation by referring to the second phase project of the free port logistics processing zone in Dongjiang, Tianjin.The change law of the distribution and dissipation of excess pore water pressure with time, depth, radial distance and permeability coefficient of soil was also discussed. It’s found that the excess pore water pressure attenuates approximately linearly with the increase of the distance from the pile heart and the scope influenced is around 10d. As the numerical simulation accord with the test results effectively, promote the results then get the change rule of pile bearing capacity with time.The formula of pile bearing capacity about time effect in dredge fill was deduced for engineering reference.The effect of soil internal friction angle on the ultimate bearing capacity of pile was discussed. Numerical simulation shows that the ultimate bearing capacity of pipe pile increases over time and keeps stable after 20d.The ultimate limit bearing capacity is 1473kN with increase of 12.3%, the time when it reaches the stable state is in accord with the excess pore water pressure dissipation monitored at each observing point. The larger the internal frictional angle of soil becomes, the more the ultimate bearing capacity is. The angle exceeding 20°,the bearing capacity would not increase as internal frictional angle of soil increases.

鋼管ぐいの閉塞効果と支持力機構(その2)

On the preceding report part-1, the principle of plugging effect and bearing mechanism of steel pipe pile was theoretically illustrated. As a serial instalment, several practical problems was discussed on this paper. Coefficients of friction between pile and soil and lateral pressure of soil which were unable to be known by the usual method of soil test, could be obtained by the experimental work with the original instruments. By the use of these factors obtained by the complementary test, the theoretical estimates of the ultimate bearing capacity of pipe piles were proved on good agreement with the observed practical field test data. A large size pipe piles driven to subgrade without enough depth of penetration cannot be expected to from a complete plug at the top of pile. Assume that a complete plug are always pproduced at the pile top, the estimates from past bearing capacity formulas are remarkably contradictory to actual value. This is very dangerous to planning of pipe pile foundation. By the theoretical mechanism described on this paper, it will enable to estimate the ultimate bearing capacity of pipe pile with practical accuracy.