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.

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.

Analysis for Interaction of Pile Group of Variable Stiffness Composite Foundation

2013 ◽  
Vol 753-755 ◽  
pp. 771-775
Author(s):  
Su Fen Zhang ◽  
Jian Hui Zhang ◽  
Xiao Yang Wang
Keyword(s):  
Design Optimization ◽  
Large Scale ◽  
Variable Stiffness ◽  
Pile Group ◽  
Composite Foundation ◽  
Scale Model ◽  
Large Scale Model ◽  
Pile Interaction

In the paper, a set of analysis formulas of pile-group of variable stiffness composite foundations was derived.The reasonability and reliability of the proposed method were showed by the results of a large scale model experiment.It is valuable to the analysis of the pile-group of composite settlement, the design optimization and the study of mechanism of pile-to-pile interaction.

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.

scholarly journals Experimental testing of a full-scale of group efficiency in multiple soil layers

2019 ◽  
Vol 13 (3) ◽  
pp. 135-142
Author(s):  
Le Thiet Trung ◽  
Duong Diep Thuy ◽  
Pham Viet Anh
Keyword(s):  
Load Transfer ◽  
Experimental Testing ◽  
Pile Group ◽  
Load Testing ◽  
Group Effect ◽  
Pile Groups ◽  
In Situ Tests ◽  
Group Efficiency ◽  
Pile Group Effect

Results of in-situ tests showed that the performance of single isolated piles and individual piles within a group is largely different. When piles are arranged in a group, the interaction between piles and the foundation depends on the pile arrangement and the pile group effect. To date, studies on the pile group effect in Vietnam have been limited to reduced-scale laboratory testing or static load testing where piles are installed into homogeneous sandy or clayey foundation. This paper presents in situ tests which were performed on both single piles and pile groups, loaded to failure, with the aim of studying the pile group effect of piles embedded in multi-layered foundation. Strain gauges were installed along the shaft of 10 m long steel pipe piles, with a diameter of 143 mm. The influence of loose sand layers on the group effect in case of friction piles was evaluated. The experimental results indicated that the influence of sand layers was evident, and the group factor was calculated to be 1.237. Keywords: group efficiency; pile groups; axial capacity; load transfer.

Geometrical effects on the load transfer mechanism of pile groups: three-dimensional numerical analysis

2018 ◽  
Vol 55 (5) ◽  
pp. 749-757 ◽  
Author(s):  
Yaru Lv ◽  
Dongdong Zhang
Keyword(s):  
Load Transfer ◽  
Three Dimensional ◽  
Bending Moment ◽  
Pile Group ◽  
Transfer Mechanism ◽  
Single Pile ◽  
Pile Groups ◽  
Load Transfer Mechanism ◽  
Side Resistance ◽  
Geometrical Effects

This paper investigates geometrical effects on the load transfer mechanism of off-ground capped pile groups subjected to vertical load by four three-dimensional numerical simulations, including a circular single pile, an X-shaped cross-sectional concrete (XCC) single pile, a 4 × 4 circular pile group, and a 4 × 4 XCC pile group. The ultimate bearing capacities of the XCC and circular piles within pile groups are approximately 0.86 and 0.74 times that of the XCC and circular single piles, respectively. The group efficiency of the XCC pile group is mainly improved by its side resistance. Comparing the XCC pile group to the circular pile group, the increment in side resistance is almost larger than the increment in pile perimeter, indicating that the pile geometry alters the load transfer mechanism via stress concentration and lateral stress arching. A nonuniform load distribution on piles within a capped pile group causes a bending moment along the pile shafts. The bending moment of XCC piles is smaller than that of circular piles because the raft stiffness of an XCC pile group is increased by its larger circumscribing pile diameter.

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.

RANCANG BANGUN PERANGKAT EKSPERIMENTASI PROSES PIROLISIS BIOMASA GELOMBANG MIKRO

2013 ◽  
Vol 14 (2) ◽  
Author(s):  
Noor Fachrizal
Keyword(s):  
Large Scale ◽  
Continuous Model ◽  
Biomass Energy ◽  
Scale Model ◽  
Small Scale ◽  
Laboratory Apparatus ◽  
Liquid Form ◽  
Large Scale Model ◽  
Bio Oil ◽  
Pyrolysis Of Biomass

Biomass such as agriculture waste and urban waste are enormous potency as energy resources instead of enviromental problem. organic waste can be converted into energy in the form of liquid fuel, solid, and syngas by using of pyrolysis technique. Pyrolysis process can yield higher liquid form when the process can be drifted into fast and flash response. It can be solved by using microwave heating method. This research is started from developing an experimentation laboratory apparatus of microwave-assisted pyrolysis of biomass energy conversion system, and conducting preliminary experiments for gaining the proof that this method can be established for driving the process properly and safely. Modifying commercial oven into laboratory apparatus has been done, it works safely, and initial experiments have been carried out, process yields bio-oil and charcoal shortly, several parameters are achieved. Some further experiments are still needed for more detail parameters. Theresults may be used to design small-scale continuous model of productionsystem, which then can be developed into large-scale model that applicable for comercial use.

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