Load tests on full-scale bored pile groups

2012 ◽  
Vol 49 (11) ◽  
pp. 1293-1308 ◽  
Author(s):  
Guoliang Dai ◽  
Rodrigo Salgado ◽  
Weiming Gong ◽  
Yanbei Zhang
Keyword(s):  
Load Transfer ◽  
Pile Group ◽  
Interaction Coefficient ◽  
Full Scale ◽  
Pile Groups ◽  
Interaction Coefficients ◽  
Bored Pile ◽  
Load Response ◽  
Load Tests ◽  
Single Piles

The interactions between closely spaced piles in a pile group are complex. Very limited experimental data are available on the loading of full-scale bored pile groups. This paper reports the results of axial static load tests of both full-scale instrumented pile groups and single piles. The load tests aimed to ascertain the influence of number, length, and spacing of the piles on pile group load response. Experiments varied in the number of piles in the group, pile spacing, type of pile groups, and pile length. All piles had a diameter of 400 mm. Two-, four-, and nine-pile groups with pile lengths of 20 and 24 m were tested. As the isolated piles and some piles in the pile groups were instrumented, the load transfer and load–settlement curves of both piles in isolation and individual instrumented piles in the groups were obtained. The interaction coefficient for each pile in the group was back-calculated from the measured data. The interaction coefficients are shown to be dependent on pile proximity, as usually assumed in elastic analyses, but also on settlement and on the size of the group.

Reply to the discussion by Fellenius on “Load tests on full-scale bored pile groups”

2013 ◽  
Vol 50 (4) ◽  
pp. 454-455 ◽  
Author(s):  
Rodrigo Salgado ◽  
Yanbei Zhang ◽  
Guoliang Dai ◽  
Weiming Gong
Keyword(s):  
Full Scale ◽  
Pile Groups ◽  
Bored Pile ◽  
Load Tests

scholarly journals Large-scale model tests of a single pile and two-pile groups for an offshore platform in sand

2021 ◽  
Author(s):  
Aligi Foglia ◽  
Khalid Abdel-Rahman ◽  
Elmar Wisotzki ◽  
Tulio Quiroz ◽  
Martin Achmus
Keyword(s):  
Large Scale ◽  
Load Transfer ◽  
Pile Group ◽  
Scale Model ◽  
Single Pile ◽  
Pile Groups ◽  
Group Efficiency ◽  
Large Scale Model ◽  
Load Tests ◽  
The Given

Estimating pile group efficiency for open-ended steel piles in small group arrangements is a challenging task for designers. This paper reports on the large-scale experimental campaign performed for the BorWin gamma offshore converter platform, which involved single piles and two-pile group systems on a scale of 1:10. The experimental works included installation, dynamic end-of-driving tests, dynamic restrike tests, and static load tests of a single pile and a pair of two-pile groups in densely compacted, artificially prepared homogeneous sand. The CPT profiles and the blow counts confirmed that the foundation systems are comparable to each other. The experimental results of the single pile system were compared with conventional design methods. Such comparison indicated that CPT-based methods and load-transfer methods are applicable at the considered model scale. The bearing capacity prediction obtained via the CAPWAP method is conservative with respect to the static capacity. A consistent setup effect can be detected by analyzing the complete dynamic loading session. The pile group efficiency for the given foundation system was found to be less than 1.0 at both very small and very large soil strains, while it equaled 1.0 at failure.

An experimental study of the interaction of vertically loaded pile groups in sand

2005 ◽  
Vol 42 (5) ◽  
pp. 1485-1493 ◽  
Author(s):  
Su-Hyung Lee ◽  
Choong-Ki Chung
Keyword(s):  
Model Test ◽  
Load Transfer ◽  
Interaction Model ◽  
Pile Group ◽  
Pile Groups ◽  
Free Standing ◽  
Pile Installation ◽  
Current Design ◽  
Load Tests ◽  
Design Factors

The interactions among closely located piles and a cap in a pile group are complex. The current design practice for vertically loaded pile groups roughly estimates their overall behavior and generally yields conservative estimations of the group capacity. For a proper pile group design, factors such as the interaction among piles, the interaction between cap and piles, and the influence of pile installation method all need to be considered. This paper presents the results of the model test, which can be used to better understand the interactions of vertically loaded pile groups in granular soil. Load tests were carried out on the following: an isolated single pile, single-loaded center piles in groups, a footing without any piling, free standing pile groups, and piled footings. The influences of pile driving and the interactions among bearing components on load–settlement and load transfer characteristics of piles and on the bearing behavior of a cap in a group are investigated separately by comparing their respective test results. The favorable interaction effects that increase pile capacities are identified.Key words: pile group, pile installation, interaction, model test, free standing, piled footing.

Full-Scale Lateral Load Tests of Pile Groups

1976 ◽  
Vol 102 (1) ◽  
pp. 87-105
Author(s):  
Jai B. Kim ◽  
Robert J. Brungraber
Keyword(s):  
Lateral Load ◽  
Full Scale ◽  
Pile Groups ◽  
Load Tests

Closure to “Full-Scale Lateral Load Tests of Pile Groups”

1977 ◽  
Vol 103 (10) ◽  
pp. 1187-1190
Author(s):  
Jai B. Kim ◽  
Robert J. Brungraber
Keyword(s):  
Lateral Load ◽  
Full Scale ◽  
Pile Groups ◽  
Load Tests

Dynamic analysis of laterally loaded pile groups in sand and clay

2002 ◽  
Vol 39 (6) ◽  
pp. 1358-1383 ◽  
Author(s):  
Yasser E Mostafa ◽  
M Hesham El Naggar
Keyword(s):  
Dynamic Loading ◽  
Dynamic Load ◽  
Load Transfer ◽  
Pile Group ◽  
Nonlinear Behaviour ◽  
Single Pile ◽  
Offshore Platforms ◽  
Group Effect ◽  
Pile Groups ◽  
Pile Head

Pile foundations supporting bridge piers, offshore platforms, and marine structures are required to resist not only static loading but also lateral dynamic loading. The static p–y curves are widely used to relate pile deflections to nonlinear soil reactions. The p-multiplier concept is used to account for the group effect by relating the load transfer curves of a pile in a group to the load transfer curves of a single pile. Some studies have examined the validity of the p-multiplier concept for the static and cyclic loading cases. However, the concept of the p-multiplier has not yet been considered for the dynamic loading case, and hence it is undertaken in the current study. An analysis of the dynamic lateral response of pile groups is described. The proposed analysis incorporates the static p–y curve approach and the plane strain assumptions to represent the soil reactions within the framework of a Winkler model. The model accounts for the nonlinear behaviour of the soil, the energy dissipation through the soil, and the pile group effect. The model was validated by analyzing the response of pile groups subjected to lateral Statnamic loading and comparing the results with field measured values. An intensive parametric study was performed employing the proposed analysis, and the results were used to establish dynamic soil reactions for single piles and pile groups for different types of sand and clay under harmonic loading with varying frequencies applied at the pile head. "Dynamic" p-multipliers were established to relate the dynamic load transfer curves of a pile in a group to the dynamic load transfer curves for a single pile. The dynamic p-multipliers were found to vary with the spacing between piles, soil type, peak amplitude of loading, and the angle between the line connecting any two piles and the direction of loading. The study indicated the effect of pile material and geometry, pile installation method, and pile head conditions on the p-multipliers. The calculated p-multipliers compared well with p-multipliers back-calculated from full scale field tests.Key words: lateral, transient loading, nonlinear, pile–soil–pile interaction, p–y curves, Statnamic.

scholarly journals 3D Numerical Modeling of Pile Group Responses to Excavation-Induced Stress Release in Silty Clay

2018 ◽  
Vol 8 (1) ◽  
pp. 2577-2584
Author(s):  
M. A. Soomro ◽  
A. S. Brohi ◽  
M. A. Soomro ◽  
D. K. Bangwar ◽  
S. A. Bhatti
Keyword(s):  
Load Transfer ◽  
Pile Group ◽  
Small Strain ◽  
Transportation Systems ◽  
Silty Clay ◽  
Pile Groups ◽  
Stress Release ◽  
3D Numerical Modeling ◽  
Hypoplastic Model ◽  
Induced Stress

Development of underground transportation systems consists of tunnels, basement construction excavations and cut and cover tunnels which may encounter existing pile groups during their construction. Since many previous studies mainly focus on the effects of excavations on single piles, settlement and load transfer mechanism of a pile group subjected to excavation-induced stress release are not well investigated and understood. To address these two issues, three-dimensional coupled-consolidation numerical analysis is conducted by using a hypoplastic model which takes small-strain stiffness into account. A non-linear pile group settlement was induced. This may be attributed to reduction of shaft resistance due to excavation induced stress release, the pile had to settle substantially to further mobilise end-bearing. Compared to the Sp of the pile group, induced settlement of the single pile is larger with similar settlement characteristics. Due to the additional settlement of the pile group, factor of safety for the pile group can be regarded as decreasing from 3.0 to 1.4, based on a displacement-based failure load criterion. Owing to non-uniform stress release, pile group tilted towards the excavation with value of 0.14%. Due to excavation-induced stress release and dragload, head load of rear piles was reduced and transferred to rear piles. This load transfer can increase the axial force in front piles by 94%.

Optimization of Pile Groups Under Vertical Loads Using Metaheuristic Algorithms

2018 ◽  
pp. 276-298 ◽  
Author(s):  
Cihan Öser ◽  
Rasim Temür
Keyword(s):  
Optimization Problems ◽  
Soil Layer ◽  
Pile Group ◽  
Optimum Number ◽  
Pile Groups ◽  
Bored Pile ◽  
Group Efficiency ◽  
Economical Design ◽  
Loose Soil ◽  
Soil Deposits

Construction of foundations on soft/loose soil deposits causes some big problems in geotechnical engineering. The vertical loads can cause failure and/or extreme settlement in soft/loose soil deposit. Constructing piles under foundations to transfer the loads to stiff soil layer is one of the widely used solutions to prevent these problems. The interaction between the piles in a group of piles is described as “group efficiency” and this interaction causes the reduction in the load-bearing capacity of the piles. For a safe and economical design, optimization must be done to estimate the optimum number of piles in the group. This chapter aims to investigate the robustness of commonly used optimization algorithms and determine the most efficient algorithms for pile group optimization problems. Consequently, the proposed methods are going to help engineers to make fast, safe, and economical designs for pile groups under vertical foundation loads. In this chapter, bearing capacities and optimization of bored pile groups constructed in soft soils are discussed.

Pile group elastic load response prediction: friction piles embedded in cohesive soils

1984 ◽  
Vol 21 (3) ◽  
pp. 587-592
Author(s):  
R. A. Douglas ◽  
R. Butterfield
Keyword(s):  
Design Procedure ◽  
Pile Group ◽  
Response Prediction ◽  
Reduction Factor ◽  
Cohesive Soils ◽  
Pile Groups ◽  
Elastic Load ◽  
Stiffness Reduction ◽  
Load Response ◽  
Group Response

Predicting the elastic vertical working load response of friction pile groups embedded in cohesive soils is a problem still requiring a solution that can be easily implemented by practising engineers. A design procedure based on an extensive analysis of the results of a computer program is presented as a solution to the problem.The program was used to study the effects of the interaction of closely spaced piles in groups, on the pile group response to loading. It is possible to define an average pile stiffness (load per unit displacement) and discuss a reduction of this stiffness, due to pile interaction, when the pile is placed in a group of similar piles. This interaction is accounted for by a stiffness reduction factor, ρ.The design approach is compared with load tests at model and full scale, with good agreement. Key words: piles, pile groups, working loads, elastic pile displacements.

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