Axial compressive capacity of driven piles in sand: a method including post-driving residual stresses

2001 ◽  
Vol 38 (2) ◽  
pp. 364-377
Author(s):  
Ahmed Shlash Alawneh ◽  
Osama Nusier ◽  
Abdullah I Husein Malkawi ◽  
Mustafa Al-Kateeb
Keyword(s):  
Residual Stresses ◽  
Bearing Capacity ◽  
Relative Density ◽  
Friction Angle ◽  
Accurate Estimate ◽  
Driven Piles ◽  
Pile Capacity ◽  
Shaft Resistance ◽  
Load Tests ◽  
Pile Load Tests

In this paper, empirical formulae were developed between the well-known pile bearing capacity factors (Nq and β) and parameters which include friction angle of sand, relative density, average effective vertical stress, and deformability of the soil below the pile toe. The developed empirical formulae were totally based on a database comprised of 28 well-documented compressive pile load tests collected exclusively from geotechnical literature. The actual measurements of shaft and end-bearing resistances of each pile in the database were adjusted to account for post-driving residual loads. Calculation of pile bearing capacity factors (Nq and β) was based on the adjusted shaft and end-bearing resistances rather than the actual unadjusted measured resistances for residual loads. Comparison of predicted and measured compressive capacity of an independent database comprised of 18 pile load tests showed that the developed formulae yield a reasonably accurate estimate of compressive pile capacity in cohesionless soils.Key words: driven piles, residual load, toe resistance, shaft resistance.

scholarly journals Empirical Shaft Resistance of Driven Piles Penetrating Weak Rock

2020 ◽  
Vol 53 (12) ◽  
pp. 5531-5543
Author(s):  
John W. Barrett ◽  
Luke J. Prendergast
Keyword(s):  
Empirical Relationship ◽  
Empirical Relation ◽  
Driven Piles ◽  
Case Histories ◽  
Pile Capacity ◽  
Shaft Resistance ◽  
Fatigue Model ◽  
Load Tests ◽  
Pile Load Tests ◽  
Engineering Projects

AbstractIn this paper, an empirical relationship between the Unconfined Compressive Strength (UCS) of intact rock and the unit shaft resistance of piles penetrating rock is investigated. A growing number of civil engineering projects are utilizing steel piles driven into rock where a significant portion of the pile capacity is derived from the shaft resistance. Despite the growing number of projects utilizing the technology, little to no guidance is offered in the literature as to how the shaft resistance is to be calculated for such piles. A database has been created for driven piles that penetrate bedrock. The database consists of 42 pile load tests of which a majority are steel H-piles. The friction fatigue model is applied to seven of the pile load tests for which sufficient UCS data exists in order to develop an empirical relation. The focus of this paper is on case histories that include driven pipe piles with at least 2 m penetration into rock.

scholarly journals Accuracy of pile capacity assessment on the basis of piling reports

2019 ◽  
Vol 97 ◽  
pp. 04029 ◽  
Author(s):  
Jakub Rainer
Keyword(s):  
Bearing Capacity ◽  
Operational Reliability ◽  
Driven Piles ◽  
Safety Factors ◽  
Pile Capacity ◽  
Current Assessment ◽  
Proper Design ◽  
Foundation Pile ◽  
Load Tests ◽  
Pile Load Tests

Current assessment of foundation pile bearing capacity during driving may considerably improve operational reliability in terms of loads to be transferred. It also enables proper design and trial examinations by focusing attention on piles with atypical driving characteristics. The paper presents the method applicable to assess the bearing capacity of prefabricated driven piles and provides analysis of likelihood of this assessment by the example of numerous prefabricated piles documented by piling reports and results of static pile load tests to the extent allowing to determining the limit bearing capacity. The results attained could be the basis to determine respective safety factors in pile design based on driving resistance analysis.

Centrifuge modelling of heating effects on energy pile performance in saturated sand

2015 ◽  
Vol 52 (8) ◽  
pp. 1045-1057 ◽  
Author(s):  
C.W.W. Ng ◽  
C. Shi ◽  
A. Gunawan ◽  
L. Laloui ◽  
H.L. Liu
Keyword(s):  
Earth Pressure ◽  
Continuous Heating ◽  
Saturated Sand ◽  
Pile Capacity ◽  
Shaft Resistance ◽  
Heating Effects ◽  
Energy Piles ◽  
Different Temperatures ◽  
Load Tests ◽  
Pile Load Tests

The operation of energy piles in summer can expel excess heat of the buildings into the ground by the use of a heat pump. Despite having been implemented for decades, the design of energy piles still relies heavily on empiricism, as there is limited understanding about heating effects on pile capacity. A series of centrifuge model tests on aluminum energy piles in medium dense saturated sand is reported in this study to investigate heating effects on the settlement patterns as well as capacities of single piles. In total, four in-flight pile load tests under three different temperatures, namely 22, 37, and 52 °C, and different loading sequences were carried out. Variations of pile capacity were interpreted with the help of a nonlinear elastic analysis. The test results show that after heating at zero applied axial load, toe resistance of the pile was mobilized as a result of constrained downward thermal expansion of the pile. Heating to a higher temperature caused the neutral plane to shift towards the pile toe due to a larger degree of mobilization of end-bearing resistance. It is also found that for a pile under a maintained working load, the pile head heaved initially by 1.4%D (D, pile diameter) when the temperature increased by 30 °C, but it gradually settled to 0.8%D after 4 months of continuous heating at the constant temperature. The post-pile settlement is believed to be caused by thermal contraction of sand. Subsequent pile load tests show that pile capacities increased by 13% and 30% with incremental temperatures of 15 and 30 °C, respectively. With an increasing temperature, shaft resistance increased but at a reducing rate. At a higher elevated temperature, toe resistance increased more rapidly than shaft resistance due to a larger downward expansion of the pile. For simplicity, earth pressure coefficients with values of 1.1K0 and 1.3K0 were found to be suitable for estimating the capacities of aluminum model piles with temperature increments of 15 and 30 °C, respectively.

Driven cast-in-situ pile capacity: insights from dynamic and static load testing

2021 ◽  
Author(s):  
Kevin N. Flynn ◽  
Bryan A. McCabe
Keyword(s):  
Dynamic Load ◽  
Shear Stresses ◽  
Load Testing ◽  
Pile Capacity ◽  
Compression Load ◽  
Shaft Resistance ◽  
Pile Installation ◽  
Cast Concrete ◽  
Load Tests

Driven cast-in-situ (DCIS) piles are classified as large displacement piles. However, the use of an oversized driving shoe introduces additional complexities influencing shaft resistance mobilisation, over and above those applicable to preformed displacement piles. Therefore, several design codes restrict the magnitude of shaft resistance in DCIS pile design. In this paper, a series of dynamic load tests was performed on the temporary steel driving tubes during DCIS pile installation at three UK sites. The instrumented piles were subsequently subjected to maintained compression load tests to failure. The mobilised shear stresses inferred from the dynamic tests during driving were two to five times smaller than those on the as-constructed piles during maintained load testing. This was attributed to soil loosening along the tube shaft arising from the oversized base shoe. Nevertheless, the radial stress reductions appear to be reversible by the freshly-cast concrete fluid pressures which provide lower-bound estimates of radial total stress inferred from the measured shear stresses during static loading. This recovery in shaft resistance is not recognised in some European design practices, resulting in conservative design lengths. Whilst the shaft resistance of DCIS piles was underpredicted by the dynamic load tests, reasonable estimates of base resistance were obtained.

Predicting the Ultimate Bearing Capacity of Single Piles Based on CPTU

2011 ◽  
Vol 243-249 ◽  
pp. 4402-4407
Author(s):  
Yong Hong Miao ◽  
Guo Jun Cai ◽  
Song Yu Liu
Keyword(s):  
Load Test ◽  
Load Testing ◽  
Pile Capacity ◽  
Piezocone Penetration Test ◽  
Load Carrying ◽  
Load Tests ◽  
Pile Load Test ◽  
Single Piles ◽  
Pile Load Tests ◽  
Best Fit

Six methods to determine axial pile capacity directly based on piezocone penetration test (CPTU) data are presented and evaluated. Analyses and evaluation were conducted on three types piles that were failed during pile load testing. The CPT methods, as well as the CPTU methods, were used to estimate the load carrying capacities of the investigated piles (Qp ). Pile load test were used to determine the measured load carrying capacities (Qm). The pile capacities determined using the different methods were compared with the measured pile capacities obtained from the pile load tests. Two criteria were selected as bases of evaluation: the best fit line for Qp versus Qm and the arithmetic mean and standard deviation for the ratio Qp /Qm. Results of the analyses showed that the best methods for determining pile capacity are the CPTU methods.

scholarly journals Bi-Directional Static Load Tests of Pile Models

2020 ◽  
Vol 10 (16) ◽  
pp. 5492
Author(s):  
Michał Baca ◽  
Włodzimierz Brząkała ◽  
Jarosław Rybak
Keyword(s):  
Bearing Capacity ◽  
Static Load ◽  
Load Testing ◽  
Pile Capacity ◽  
Pile Shaft ◽  
Load Tests ◽  
S Curve ◽  
Definition Of ◽  
Standard Tests ◽  
Static Load Testing

This work examined a new method of bi-directional static load testing for piles, referencing the Osterberg test. Measurements were taken, on a laboratory scale, using six models of piles driven into a box filled with sand. This method allowed for separate measurements of pile base and pile shaft bearing capacities. Based on the results, the total pile bearing capacity and equivalent Q–s diagrams were estimated. The results obtained show that the structure of the equivalent curve according to Osterberg is a good approximation of the standard Q–s curve obtained from load tests, except for loads close to the limit of bearing capacity (those estimates are also complicated by the inapplicability and ambiguity of a definition of the notion of limit bearing capacity); the equivalent pile capacity in the Osterberg method represents, on average, about 80% of the capacity from standard tests.

scholarly journals Large-diameter helical pile capacity – torque correlations

2017 ◽  
Vol 54 (7) ◽  
pp. 968-986 ◽  
Author(s):  
Jared Harnish ◽  
M. Hesham El Naggar
Keyword(s):  
Large Diameter ◽  
Failure Criteria ◽  
Load Test ◽  
Ultimate Capacity ◽  
Pile Capacity ◽  
Shearing Resistance ◽  
Helical Piles ◽  
Torque Capacity ◽  
Load Tests ◽  
Pile Load Tests

Large-diameter helical piles are utilized increasingly to support heavy structures. Both the magnitude of the required installation torque and the pile capacity can be directly attributed to the soil shearing resistance developed over the embedded area of the pile including the shaft and helical plates. Hence, the pile capacity can be correlated to installation torque. Such correlations are widely used in the helical pile industry as a means for quality control and quality assurance. In the current study, a total of 10 test piles were installed while monitoring the installation torque continuously with depth. The recorded installation torque profiles were demonstrated to be accurate and repeatable. Field pile load tests were conducted and their results were analyzed to determine the interpreted ultimate capacity of the test piles. The results demonstrate that the ultimate capacity of large-diameter helical piles can be interpreted from pile load test data employing the failure criteria proposed by Elkasabgy and El Naggar in 2015 and Fuller and Hoy in 1970. The measured installation torque and corresponding ultimate capacity values were employed to define torque–capacity correlation (Kt) based on embedded pile area. It was demonstrated that the proposed Kt is suitable for large-diameter helical piles.

scholarly journals Neural networks and principle component analysis approaches to predict pile capacity in sand

2018 ◽  
Vol 149 ◽  
pp. 02025 ◽  
Author(s):  
A Benali ◽  
A Nechnech ◽  
B Boukhatem ◽  
M N Hussein ◽  
M Karry
Keyword(s):  
Neural Networks ◽  
Bearing Capacity ◽  
Driven Piles ◽  
In Situ Tests ◽  
Pile Capacity ◽  
Significant Development ◽  
Pca Method ◽  
Main Component

Determination of pile bearing capacity from the in-situ tests has developed considerably due to the significant development of their technology. The project presented in this paper is a combination of two approaches, artificial neural networks and main component analyses that allow the development of a neural network model that provides a more accurate prediction of axial load bearing capacity based on the SPT test data. The retropropagation multi-layer perceptron with Bayesian regularization (RB) was used in this model. This was established by the incorporation of about 260 data, obtained from the published literature, of experimental programs for large displacement driven piles. The PCA method is proposed for compression and suppression of the correlation between these data. This will improve the performance of generalization of the model.

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