Group effect on driven piles under lateral load

The behavior of a pile group under lateral load is studied through laboratory experiments on aluminum pipe piles with outer diameters of 18.2 mm. Piles were driven in medium to fine sand with 60% relative density in different configurations and were subjected to lateral toad under fixed head conditions. Some of the piles were instrumented with strain gauges to measure bending moments at varying depths. To quantify the effect of pile driving, the behavior of a single driven pile is compared with that of a bared pile. Test data are analyzed to arrive at the group effect for various spacings. The results are presented in a nondimensional form and a method for the prediction of field group behavior is illustrated. The predictions are compared with the field results from the literature and are found to be in favorable agreement.