Doctor of Philosophy (PhD)


Department of Civil & Environmental Engineering

Document Type



Piles play an important role in transportation and bridges. They are used to resist axial and lateral loads transferred to them from structures, earth pressures, incline loads, vehicles, etc. In this study, the capacity of piles for axial and lateral loads is investigated.

The ultimate axial capacity of piles can be estimated using different approaches including static pile load tests, dynamic load tests, statnamic load tests, and static analysis based on laboratory tests (effective and total stress approaches) or in-situ tests (SPT, CPT, etc.). For each approach, different researchers have proposed different solutions for different soils and different piles. Mostly, engineers use their engineering judgement based on the available information to estimate the pile’s length and diameter (or width). In this study, different pile-CPT methods were evaluated to estimate the accuracy and precision of them for estimating the axial capacity of the piles. Based on the obtained results, the log-normal distribution of the estimated to measured pile capacity for top-ranked pile-CPT methods was adopted to develop combined pile-CPT methods that optimize the estimation accuracy of axial pile capacity in different soil categories. Also, a model for estimating axial pile capacity was developed based on the results of 10 instrumented piles and 80 piles driven in Louisiana.

For analyzing the lateral capacity of the piles, finite element method was used to obtain p-y curves. p-y curves is a simple and accurate approach that considers a nonlinear function for soil reaction with pile displacement. Different parameters for sands and clays were studied to find the effects of each parameter on the p-y curve characteristics. Models were developed for clays and sands that consider these parameters. Using the results from the parametric study, numerical models for the ultimate resistance, initial slope, and characteristic shape function are verified and compared to the existing models.

Committee Chair

Abu-Farsakh, Murad