Assessment of the Axial Capacity of In-Place Piles: Quantifying Aging Effects and Scour Impacts

Author

Isam Adnan Soliman Khasib, Louisiana State University and Agricultural and Mechanical CollegeFollow

Degree

Doctor of Philosophy (PhD)

Department

Department of Civil and Environmental Engineering

Document Type

Dissertation

Abstract

This study evaluated the axial capacity of piles that have been in service for approximately 50 years in Louisiana bridges to determine their suitability for reuse. These piles were affected primarily by two factors: setup and scour. Because the bridges will remain in service, the assessment began with proof load testing to obtain partial load settlement curves for the embedded piles. These curves were then extrapolated using validated empirical extrapolation methods previously tested on the Louisiana pile load test database. Additional approaches used to estimate axial capacity included Cone Penetration Test CPT based methods, finite element analysis using FB MultiPier, machine learning techniques, and seismic based methods. Since these approaches do not account for aging setup, aging effects were quantified separately and then applied to the predicted capacities.

To quantify the increase in capacity due to consolidation and aging setup, databases for consolidation setup A_c in clay and aging setup A_g in clay and sand were compiled. The consolidation setup database included 14 instrumented piles from Louisiana and Florida. Because aging data are limited, all available studies were assembled to determine A_g for both clay and sand. The top performing direct CPT based methods identified in prior studies were further evaluated for estimating axial capacity, including separation of side and end bearing components and assessment at the soil layer scale at 14 days, prior to calibration for A_c and A_g. Small scale test piles were also driven at multiple Louisiana sites to measure field capacity increases after dissipation of excess pore water pressure and to determine A_g.

To study scour effects, finite element FE models were developed in Abaqus, simulating the full pile installation process prior to scour modeling. Both general and local scour were analyzed. General scour simulations included layered Louisiana soil profiles and individual soil types to quantify capacity reduction and derive scour factors as functions of effective stress. These factors were synthesized into an equation relating scour to effective stress and soil properties. Local scour was evaluated by comparing effective stress reductions with available prediction methods, producing soil specific scour factors and a new equation incorporating soil parameters and scour hole geometry.

Finally, pile installation and consolidation were simulated to quantify changes in effective stress (K= σ_h′/σ_v′), providing correlations necessary for accurate capacity estimation and pile reuse design.

Date

12-15-2025

Recommended Citation

Khasib, Isam Adnan Soliman, "Assessment of the Axial Capacity of In-Place Piles: Quantifying Aging Effects and Scour Impacts" (2025). LSU Doctoral Dissertations. 6968.
https://repository.lsu.edu/gradschool_dissertations/6968

Committee Chair

Abu-Farsakh, Murad