CENTRIFUGE TESTING OF LARGE LATERALLY LOADED PILE GROUPS IN SANDS

An apparatus was developed to load large pile groups (3 x 3 to 7 x 3) founded in sand in the centrifuge laterally The device consists of a h ydraulic jack apparatus to install the piles, strain gauge instrumenta tion, and a data acquisition system. The instrumentation allowed the d etermination of both bending moments and shear forces at the head of e ach pile. Lateral load tests of 3 x 3 to 7 x pile groups were conducte d in both loose and medium dense sands. Based on the test results, the pile group interaction effects were investigated. It was found that t he p-y multiplier concept was valid. Also, the p-y multipliers (p spec ifically) are found to be independent of soil density and only a funct ion of the pile group geometry. For this study (pile spacing was fixed at 3 diameters), they were found to be only a function of row positio n. Single pile tests were also completed for comparison purposes.