Zhou, Zhihao2024-09-032024-09-032024https://hdl.handle.net/1828/20355Marl along the southeast coast of the US, especially in South Carolina and Georgia, is a stiff, calcium carbonate-rich, over-consolidated fine-grained soil commonly used as a bearing layer for pile foundations. However, two significant engineering challenges arise: unreliable CPT-based estimations of pile resistance and strain-softening behavior complicating the prediction of pile capacity, deformation, and load-transfer mechanisms under axial load. Comprehensive pile load tests conducted in Savannah, Georgia, were used to improve CPT-based pile resistance estimations and develop a numerical model using load-transfer (t-z and Q-z) method for driven and Continuous Flight Auger (CFA) piles. For CPT-based pile resistance estimations, the accuracy of the original LCPC and Eslami and Fellenius methods was first evaluated. Pile load test results were then used to back-calculate the coefficients of these methods for improvement, which were subsequently verified with additional pile load test data. The main strength parameters of the load-transfer (t-z and Q-z) method model were correlated with the improved CPT methods coefficients. After calibration, the numerical model was verified using additional pile load test data. Moreover, a 3D continuum finite element method (FEM) simulation using the ‘OC Clay’ model in Plaxis 3D was conducted to capture strain-softening behavior and examine load-transfer mechanisms. The 3D continuum FEM model was calibrated and validated against separate pile load test data, and a parametric study was conducted to investigate how soil strength parameter, pile dimensions, and embedment depth into marl influence pile performance.enAvailable to the World Wide Webmarldriven pileCFA pilenumerical simulationT-z methodCPT correlation3D continuum finite element methodThesis