Composite pile response to vertical, lateral and combined loading: experimental and numerical analysis

Al-Darraji, F (2025) Composite pile response to vertical, lateral and combined loading: experimental and numerical analysis. Doctoral thesis, Liverpool John Moores University.

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Abstract

Composite piles offer an alternative material for deep foundations, addressing many durability issues associated with traditional piling materials. Existing studies predominantly focus on single piles, exploring load transfer mechanisms and flexural responses under vertical or lateral loading. In practice, piles are often utilized in groups, where their behaviour differs significantly from that of individual piles. Furthermore, piles typically experience combined vertical and lateral loading conditions.
The study specifically examines the performance of a novel composite pile system—Confined Concrete-Filled Aluminum Tube (CCFAT) piles—installed in the sand and subjected to vertical, lateral, and combined loads. Experimental tests were conducted to analyse the vertical, lateral, and combined responses of CCFAT piles with different configurations and slenderness ratios (Lm/D ranging from 10 to 20) in both loose and dense sand. For benchmarking purposes, two conventional piles were also tested under identical conditions. The experimental results served as a foundation for validating Finite Element (FE) models, which were subsequently used to simulate additional configurations, including 2x3 and 3x3 CCFAT pile groups.
The results demonstrated that CCFAT piles exhibit ultimate capacities comparable to, or greater than, those of the reference piles under both vertical and lateral loading. Moreover, CCFAT piles consistently displayed superior ultimate lateral capacities. For all CCFAT configurations, ultimate vertical and lateral capacities increased with higher slenderness ratios and denser sand conditions. Notably, a consistent maximum bending moment depth was observed for CCFAT piles with a Lm/D ratio of 10, while a slight increase was noted for those with a Lm/D ratio of 20, attributed to the enhanced rigidity of the piles. FE analyses revealed that increasing the number of piles in a group further improved both ultimate vertical and lateral capacities. The study also explored soil movement, lateral stress distribution, and failure mechanisms, enhancing the understanding of load transfer in CCFAT piles. Sensitivity analyses identified the dilatancy angle as the primary factor influencing vertical capacity, while lateral capacity was predominantly affected by the internal friction angle. Based on these findings, fitted charts were developed to aid in estimating the ultimate vertical and lateral capacities of CCFAT piles, accounting for pile group stiffness.
Under combined loading conditions, results indicated that vertical loads enhanced the lateral performance of CCFAT pile, groups, particularly in dense sand. Key factors influencing lateral behaviour under combined loading included slenderness ratios, dilatancy angles, internal friction angles, and pile stiffness. The pile groups exhibited similar failure mechanisms under pure lateral and combined loading, characterized by rotation about a central point beneath the surface and soil deformation between piles. Finally, an expression was formulated to predict the ultimate lateral load capacity (Pulv) of CCFAT pile groups under combined loading, integrating individual ultimate vertical and lateral loads along with identified influencing factors.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	Composite piles
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Divisions:	Civil Engineering and Built Environment
Date of acceptance:	1 November 2025
Date of first compliant Open Access:	5 November 2025
Date Deposited:	05 Nov 2025 11:16
Last Modified:	05 Nov 2025 11:16
DOI or ID number:	10.24377/LJMU.t.00027427
Supervisors:	Marolt Cebasek, T, Sadique, M and Shubbar, A
URI:	https://researchonline.ljmu.ac.uk/id/eprint/27427

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