Analysis of Statnamic Behavior of Full-Scale Pile Group in Soft Clays and Silts

Dynamic behavior of a pile group is simulated by a two-dimensional finite element analysis. Results of the full-scale lateral-load tests of a 3 x 5 pile group conducted in the Salt Lake City International Airport site are compared with the simulation. The soil profile at the test site generally consisted of cohesive sandy silt and silty sand. Closed-end steel pipe piles were driven to a depth of 11.6 m. Pile head was rotation free. Dynamic lateral loads were applied to pile head with the statnamic device. To conduct numerical analysis, model parameters for soils are taken from the geotechnical investigation data at the test site. Response of five piles in the middle of the 3 x 5 pile group are simulated. Measured dynamic loads are applied at the pile head. Overall load-deflection behavior of the pile group agrees well with the measured ones. Some discrepancies are found on the bending moment profile. In the full-scale dynamic tests, peak moments for larger target deflections occurred at the same depths for all piles, while in computation, the peak moment occurs with greater depths as target deflection increases. Numerical analysis overestimates the group effects in dynamic tests. This calls up further improvement of a numerical modeling.