To investigate the lateral load distribution of each pile in a pile group, the bending moment distribution along the pile and the lateral group displacements with respect to pile location in the group, pile spacing, pile diameter and soil stiffness three dimensional finite element analysis were performed on 4x4 pile groups in clay. Different Elatic Modulus values, pile spacings, pile diameters and lateral load levels used in this study. In the analysis PLAXIS 3D Foundation geotechnical finite element package was used. It is found that, lateral load distribution among the piles was mainly a function of row location in the group independent from pile spacing. For a given load the leading row piles carried the greatest load. However, the trailing row piles carried almost the same loads. For a given load, bending moment values of the leading row piles were greater than the trailing row piles. On the other hand, as the spacing increased group displacements and individual pile loads decreased under the same applied load. However, this behavior was seen more clearly in the first and the second row piles. For the third and the fourth row piles, pile spacing became a less significant factor affecting the load distribution. It is also found that, pile diameter and soil stiffness are not significant factors on lateral load distribution as row location and pile spacing.

The present thesis evaluates numerically and experimentally if the axial capacity of Auger Cast Piles (ACPs) constructed in interbedded layers of granular soil and Limestone should be reduced as a function of pile spacing. The numerical component of this thesis includes a series of parametric studies that consider different sets of normalized spacings, stiffness ratios, relative densities, unconfined compressive strengths, and installation effects for multiple subsurface conditions. The experimental program designed herein involves the construction of multiple components for a laboratory testing program of small-scale physical models that will validate the results of the numerical models in terms of capacities, efficiency ratios and normalized spacings.