Load Sharing and Carrying Mechanism of Piles in Non-connected Pile Rafts Using a Numerical Approach

Azizkandi, Alireza Saeedi; Rasouli, Habib; Baziar, Mohammad Hassan

doi:10.1007/s40999-018-0356-2

Cited by 24 publications

(12 citation statements)

References 20 publications

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“…As it is well understood from the vertical load-carrying characteristics of CFG pile composite foundation, the percentage vertical load borne by the soil between piles decreases as the number of piles increases. [43,55,56] In line with this, the stress invariants for the monitoring element in the composite foundation with 25 piles were smaller than that of the group with nine piles. Accordingly, as shown in Figure 9, the mean isotropic state of stress for the stress element C on the p-q plane for the group with nine piles was higher for the applied working load.…”

Section: Effect Of Number Of Piles In the Composite Foundationsupporting

confidence: 64%

“…The model comprised structural (pile, raft and wall) and geotechnical (soil and cushion) parts that were modelled as elastic and elastic ideal plastic Mohr-Coulomb constitutive model, respectively. Even though Mohr-Coulomb model is not a state-of-the-art constitutive relation, it has widely been employed in FE analysis to describe the engineering characteristics of geotechnical materials while investigating the behaviour of composite piled raft foundations [6,10,[43][44][45] and performance of deep foundation pit excavations and/or their influence on the surrounding infrastructures. [26,46,47] Figure 1 depicts the typical meshed geometry employed in the model.…”

Section: Methodology Of Analysis 21 Finite Element Modellingmentioning

confidence: 99%

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Numerical study on stress paths in grounds reinforced with long and short CFG piles during adjacent rigid retaining wall movement

Uge

Guo

Liu

2022

Studia Geotechnica Et Mechanica

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Ensuring the safety of existing structures is an important issue when planning and executing adjacent new foundation pit excavations. Hence, understanding the stress state conditions experienced by the soil element behind a retaining wall at a given location during different excavation stages has been a key observational modelling aspect of the performance of excavations. By establishing and carrying out sophisticated soil–structure interaction analyses, stress paths render clarity on soil deformation mechanism. On the other hand, column-type soft ground treatment has recently got exceeding attention and practical implementation. So, the soil stress–strain response to excavation-induced disturbances needs to be known as well. To this end, this paper discusses the stress change and redistribution phenomena in a treated ground based on 3D numerical analyses. The simulation was verified against results from a 1 g indoor experimental test conducted on composite foundation reinforced with long and short cement–fly ash–gravel (CFG) pile adjacent to a moving rigid retaining wall. It was observed that the stress path for each monitoring point in the shallow depth undergoes a process of stress unloading at various dropping amounts of principal stress components in a complex manner. The closer the soil element is to the wall, the more it experiences a change in principal stress components as the wall movement progresses; also, the induced stress disturbance weakens significantly as the observation point becomes farther away from the wall. Accordingly, the overall vertical load-sharing percentage of the upper soil reduces proportionally.

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Section: Effect Of Number Of Piles In the Composite Foundationsupporting

confidence: 64%

Section: Methodology Of Analysis 21 Finite Element Modellingmentioning

confidence: 99%

Numerical study on stress paths in grounds reinforced with long and short CFG piles during adjacent rigid retaining wall movement

Uge

Guo

Liu

2022

Studia Geotechnica Et Mechanica

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“…In [23], they quantitatively described the pile-subsoil relative displacement by introducing a normalized ratio as follows:…”

Section: Load Transfer Mechanismmentioning

confidence: 99%

Improved Performance of Raft Foundation Using Detached Pile Columns in Loose Subsoil Conditions

Melese

2022

Advances in Civil Engineering

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Piles act as settlement reducers in case of connected piled-raft foundation and hence decrease the settlements of the raft. The design concept of the connected piled-raft foundations is to lessen the number of piles and utilize the bearing capacity of the system piled raft. Due to significant straining actions at the pile head-raft connection, an alternative technique is proposed to disconnect the piles from the raft. A granular layer (cushion) beneath the raft is incorporated. The disconnection has a beneficial effect on reducing axial load compared to connected piles. For small piled rafts, nonconnected piled rafts show less stiffness than connected piled rafts, and the soil is highly stressed and shows greater raft settlement. In the case of the large piled raft, nonconnected piled rafts show greater settlement efficiency. Cushion stiffness was realized to be more substantial for a nonconnected piled raft with shorter piles than one with longer piles. The results show that the load transfer mechanism in a nonconnected piled raft is mainly governed by the thickness and stiffness of the cushion layer and by the stiffness of the subsoil.

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“…Increase in soil stiffness decreases excavation-induced bending moment and horizontal deformation of nearby piles [58]. It also affects pile's response under vertical loading [53,59]. In addition, it is apparent that the compressibility characteristics of the subsoil depends on its stiffness and affects the pile-soil relative settlement, hence influencing the load sharing characteristics of a composite foundation.…”

Section: Effect Of Subsoil Stiffnessmentioning

confidence: 99%

Numerical Analysis on the Load Sharing Performance of Long‐Short CFG Pile Composite Foundation Subjected to Rotation of Adjacent Retaining Wall

Uge

Guo

Liu

2021

Advances in Civil Engineering

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The stress and displacement boundary conditions of excavation retaining structures affect the deformation mechanism and movement of the retained soil mass. The soil movement disturbs the load sharing performance and structural integrity of cement-fly ash-gravel (CFG) pile composite foundations existing in the vicinity, which merits considerable research work. This article presents results from 3D finite element analyses performed to study the influence of retaining wall rotation on the load sharing characteristics of adjacent CFG pile composite foundation comprising long and short piles. To verify the numerical model, a relatively large-scale 1 g physical model test was conducted. It is revealed that to arrive at a new static equilibrium during progression of wall rotation, the percentage load sharing ratios of the long and short piles change increasingly while the load proportion carried by the upper soil reduces remarkably. The percentage load sharing characteristics of CFG pile composite foundation are more affected in immediate proximity to the wall than those located at far distance. For the foundation having 3 × 3 long and short piles placed at 3.0–15.0 m away from the wall, the location resulted in a reduction of soil bearing capacity ranging between 1.4 and 7.5% of the total imposed load while the corresponding increase in the % load borne by the long and short pile range was 0.83–4.15 and 0.59–3.36%, respectively. For the other parameters considered in this article viz. pile spacing, subsoil stiffness, cushion stiffness and thickness, and applied working load, the increment in % load sharing of the long and short pile range was 3.45–4.15, 1.3–5.79, 1.48–3.36, 4.15–4.79, and 3.67–4.15% and 3.36–4.67, 1.43–4.99, 1.48–3.36, 3.36–3.64, and 1.38–3.36% of the imposed load, respectively. Moreover, the long piles’ load sharing proportion was higher than that of short piles, and peripheral piles received larger load proportion.

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Load Sharing and Carrying Mechanism of Piles in Non-connected Pile Rafts Using a Numerical Approach

Cited by 24 publications

References 20 publications

Numerical study on stress paths in grounds reinforced with long and short CFG piles during adjacent rigid retaining wall movement

Numerical study on stress paths in grounds reinforced with long and short CFG piles during adjacent rigid retaining wall movement

Improved Performance of Raft Foundation Using Detached Pile Columns in Loose Subsoil Conditions

Numerical Analysis on the Load Sharing Performance of Long‐Short CFG Pile Composite Foundation Subjected to Rotation of Adjacent Retaining Wall

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