Moment-carrying capacity of short pile foundations in cohesionless soil

Centrifuge and conventional model studies in which short pile foundations were subjected to large overturning moments are reported. The centrifuge tests were carried out on small model piles with lengths ranging from 40 to 100 mm and diameters from 20 to 50 mm embedded in dense and loose cohesionless soil. Lateral pull was applied at levels between 40 and 320 mm above the ground surface. Tests were performed at accelerations between 12 and 50g to simulate the behavior of prototype piles ranging from 0.125 to 1 m in diameter. Soil packing, pulling height, pile geometry, and ground surface profile are shown to influence moment-carrying capacity significantly. Centrifuge tests were also carried out on embedded walls to establish empirical shape factors for potential use in conjunction with two-dimensional theoretical analyses. These shape factors were found to increase significantly with pile embedment ratio. Conventional tests at unit gravity performed on 100-mm-diameter piles ranging in length from 200 to 500 mm generally confirm the centrifuge work. Prototype moment limits derived from the centrifuge results compare reasonably well with predictions from the design methods of Broms, McCorkle, and UIC/ORE.