3D numerical analysis of piled raft foundation in stone column improved soft soil

Samanta, Manojit; Bhowmik, Riya

doi:10.1080/19386362.2017.1368139

Cited by 31 publications

(11 citation statements)

References 24 publications

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“…Figure 7 indicates the proportion of load carried by the central, inner, edge, and corner individual piles. Before wall rotation, the corner pile carried the highest pile head load compared to the central pile, which is in tandem with previous studies [12,14,50]. However, at the final rotation of the wall, the pile head load computed for shorter piles close to the wall became relatively larger and increased at a higher rate than the others while the increment for the long pile head load increased with increasing the wall rotation to a certain amount, e.g., 20-25 × 10 −4 rad, and then due to pilepile interaction effect, it afterward started decreasing with the corner pile (pile A) attaining a 4% increment but the edge (pile C) 1% decrement at the end of wall rotation as compared to their initial values.…”

Section: Effect Of Number Of Pilessupporting

confidence: 89%

“…Beyond the spacing of 8 times the pile diameter, the group effect and arching would not be felt, and the failure mode of the soil surrounding the piles would be the same as that of a single pile [48]. In composite pile foundation, pile spacing directly reflects one of the basic load sharing parameters, the pile area replacement ratio, m. Apart from changing the spacing, the area replacement ratio can also be varied by increasing the diameter of the pile (or its head) [50,52,53] and/or provision of pile cap [54,55]. From the mechanical characteristics of CFG pile composite foundation, it is well known that the smaller the clearance between neighbouring piles, the larger the cover ratio of piles and the smaller the load sharing proportion of the soil, meanwhile reducing the foundation settlement.…”

Section: Effect Of Pile Spacingmentioning

confidence: 99%

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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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Section: Effect Of Number Of Pilessupporting

confidence: 89%

Section: Effect Of Pile Spacingmentioning

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 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%

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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“…Short piles can be selected from rigid piles, semirigid piles, or flexible piles and are mainly used to improve the bearing capacity of composite foundations [15]. is is similar to the concepts of composite piled raft foundation and multielement composite foundations proposed by scholars [16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 94%

“…e results revealed multielement composite foundations (such as a combination of steel pipe pile and sand column or a combination of concrete pile and lime column) have a higher bearing capacity than the composite foundation with only sand columns with the same conditions. rough three-dimensional finite element software, Samanta and Bhowmik [19,20] studied the efficacy of improving the soft soil by stone columns on the response of a piled raft foundation. Studies showed that reinforcing the shallow soft soil with stone columns can effectively improve the bearing interaction of the raft.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Deformation Characteristics of Long‐Short Pile Composite Foundation in Salt Lake Area, Iran

Liu¹,

Yang

Zhang

et al. 2019

Advances in Civil Engineering

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To study the settlement and deformation characteristics of a long-short pile composite foundation and its influencing factors, the indoor centrifuge model test and numerical simulations were performed under the actual working conditions to treat the saline soft soil foundation in the Soltan salt lake area of Iran. Firstly, the settlement of a long-short pile composite foundation and the law of pile-soil stress ratio development with time were studied using a centrifuge model test. In addition, FLAC3D was used to simulate the test conditions, and it has been observed that the numerical and experimental results were in good agreement. Based on the numerical model, the effects of the replacement rate of long and short piles, cushion modulus, and pile length on the settlement of the composite foundation and the stress ratio of long and short piles were analyzed. The results show that the long-short pile composite foundation can effectively control settlement. Compared to the untreated foundation, the total settlement of a long-short pile composite foundation was reduced by 67%, and the postconstruction settlement was reduced by 47.7%. Compared to the final settlement of the composite foundation obtained using the centrifuge model test, the error range of the numerical simulation results was between 2.4% and 8%. The influence of pile spacing on the settlement and stress characteristics of a long-short pile composite foundation is greater than that attributable to the arrangement of the piles. Under this geological condition, it is reasonable to choose a pile spacing of 4d∼5d. When the long pile reaches the bearing stratum, the length of the short pile should not exceed 0.6 times the length of the long pile. The setting cushion not only reduces uneven settlement of the composite foundation but also improves the joint bearing capacity of the pile and the soil between the piles.

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3D numerical analysis of piled raft foundation in stone column improved soft soil

Cited by 31 publications

References 24 publications

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

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

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

Analysis of Deformation Characteristics of Long‐Short Pile Composite Foundation in Salt Lake Area, Iran

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