E-Thesis 257 views
Numerical Modelling of Tremie Concrete in Deep Foundation Construction / THOMAS MITCHELL
Swansea University Author: THOMAS MITCHELL
DOI (Published version): 10.23889/SUThesis.69217
Abstract
Cast-in-place deep foundation structures, such as bored piles and diaphragm wall panels, are typically constructed using the tremie method. This approach utilises a hopper and tremie pipe to place concrete via gravity feed in submerged conditions. The concrete used, referred to as tremie concrete, r...
| Published: |
Swansea University, Wales, UK
2025
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| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | Ph.D |
| Supervisor: | Li, C |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa69217 |
| Abstract: |
Cast-in-place deep foundation structures, such as bored piles and diaphragm wall panels, are typically constructed using the tremie method. This approach utilises a hopper and tremie pipe to place concrete via gravity feed in submerged conditions. The concrete used, referred to as tremie concrete, requires specific rheological properties to produce defect-free elements. High workability and stability are essential for adequate form-filling while resisting shear forces and hydrostatic pressures that can induce segregation and bleeding. Numerical modelling, namely Computational Fluid Dynamics (CFD), is employed to simulate the concrete pouring process within bored piles. A novel, multiphase, gravity-driven flow model is developed in OpenFOAM® to more accurately capture the pouring process of the tremie method. Within the model, concrete flow is driven by the pressure differential brought about by the difference in concrete level between the tremie and pile. The deceleration of concrete flow over time is found to be the cause of the shell-like concrete flow pattern that has been observed within the literature. This numerical model is used to study the impact of pile design, construction techniques, and insufficient base cleaning on concrete flow within bored piles; the scope of these studies is governed by criteria defined in industry specifications. The observed flow mechanisms are linked to the likelihood of physical defect generation. Low-energy concrete flow within the cover zone is identified as the fundamental cause of defects, negatively affected by reduced reinforcement clear spacing, decreased cover zone size, debris on the pile base, and low-workability concrete. A computationally efficient method is developed to simulate the concrete pouring process of industry-scale bored piles. The tremie-breaking sequence is captured, and individual concrete charges are tracked by implementing a passive scalar transport function into theinterFoam solver within OpenFOAM®. This model confirms that two main bulk-flow mechanisms occur at full scale depending on whether the pile is reinforced or unreinforced: restricted, "bulging" flow and unrestricted, "plug" flow, respectively. When unrestricted flow is observed, longer concrete workability retention is required to maintain sufficient flow and decrease the likelihood of undesirable flow mechanisms. In summary, pile design should be considered a holistic process, where both concrete mix design and structural requirements are developed simultaneously. Designers should avoid implementing multiple flow-restricting features within piles to reduce the likelihood of defect generation. |
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| Item Description: |
A selection of content is redacted or is partially redacted from this thesis to protect sensitive and personal information |
| Keywords: |
Computational Fluid Dynamics, Tremie Concrete, Defects, Multiphase Flow, Bored Piles |
| College: |
Faculty of Science and Engineering |
| Funders: |
Arup, EPSRC CASE PhD |