Combined Horizontal-Vertical loading of Square Foundation in the Offshore Niger Delta of Nigeria

The performance of a square foundation on clay in the offshore Niger Delta subjected to combined horizontal – vertical loading has been attempted .Horizontal forces were evaluated from the impact of varying wave heights on circular piles of 1.0 to 2.0m diameter using available wave height records, while concentric vertical loadings were evaluated from empirical methods of Skempton, Brinch Hanson, and Vesic. The results revealed that sliding failure commenced when the ratio of vertical load to footing area and undrained shear strength (V/Asu) assumes negative values (i.e. at H/Asu > 3.427) and for footing stability, the vertical load should be at least twice the anticipated horizontal load. For foundation with the ratio of footing depth to breadth greater than one ( Df /B>1.0), higher horizontal force of about 10.5 times greater than those for Df /B<1.0 are required to initiate sliding.