Doctor of Philosophy
Civil and Environmental Engineering
Hesham El Naggar
Bored and continuous flight auger (CFA) piles are two widely used cast in place reinforced concrete pile types that are constructed employing different techniques, which affect their performance and capacity. However, both are classified as non-displacement piles and are designed accordingly using the same method. Therefore, the objective of this work is to comparatively investigate the axial and lateral performance of bored and CFA piles installed in sand. In addition, the potential of constructing sustainable piles utilizing green concrete mixture that incorporates treated oil sand waste (TOSW) was investigated. Fresh and hardened properties along with durability performance of CFA concrete mixtures incorporating 10%, 20%, 30% and 40% TOSW as partial replacement of sand were investigated. Six piles with the same nominal geometry were constructed using conventional and green concrete mixtures. The piles were subjected to axial monotonic compressive and uplift loading as well as monotonic and cyclic lateral loading. The test piles were exhumed after testing to investigate their dimensions and profile, surface roughness, and interface friction between soil and pile. The soil-pile interface conditions of bored and CFA piles were quantitatively characterized using fractal dimension to measure surface roughness. Finally, three-dimensional non-linear finite element models were developed utilizing Plaxis 3D software to simulate the behaviour of the bored and CFA piles under monotonic compression, uplift, and lateral loading. A parametric study was carried out to investigate the effect of the angle of internal friction and the pile diameter on its behaviour and capacity under different loading cases. The results showed that the addition of TOSW, up to 30% replacement of sand, did not adversely affect the performance of CFA concrete mixtures. CFA piles had higher compressive, pullout, and lateral ii capacity compared to bored piles. This was attributed to the increase in diameter of the CFA piles compared to the bored piles owing to the high pressure used for placing the concrete in CFA construction, which led to higher lateral soil confinement. It was also found that piles constructed employing concrete mixture incorporating TOSW had the same geotechnical performance as those constructed utilizing conventional concrete mixture. Finally, the numerical analysis demonstrated that the effects of construction technique should be accounted for in order to properly simulate the CFA pile behaviour.
Kassem, Mahmoud, "Comparative Investigation of Bored and Continuous Flight Auger Piles with Consideration of Green Concrete" (2017). Electronic Thesis and Dissertation Repository. 4604.