Experimental Studies on Behavior of Single Pile under Combined Uplift and Lateral Loading

Abstract

1-g model experiments were carried out in the laboratory to investigate the behavior of a single pile in sand under combined uplift and lateral load. Dimensions of the model pile were ascertained using physical scaling laws, based on adopted material properties of model and prototype pile foundations. The model pile is made up of aluminum and has outer and inner diameters of 25.4 and 19.0 mm, respectively. Different length-to-diameter ratios of 18, 28, and 38 are considered by varying the pile length to simulate behavior of both stiff and flexible piles. The test tank dimensions were chosen such that boundary effects are minimized. The size of the model steel tank is 1.0×1.0×1.2 m (depth). Experiments were performed on single piles embedded in sandy soil under independent uplift and lateral loading, and combined lateral and uplift loading. Results indicate that the load-deflection behavior is nonlinear for independent uplift and lateral load tests, as well as in the case of combined loading. It is also observed that the behavior of piles under independent loading is substantially different when compared to combined loading. It is found that the ultimate lateral/uplift load capacity under combined loading increased considerably; however, the pile head deflection/displacement at safe lateral/uplift load is found to increase under combined loading. This indicates that although the capacity is increasing under combined load, considering this increased pile capacity may not be possible in a practical design. Rather the safe lateral/uplift loads that are being used in the current design may need to be verified for satisfying the limiting deflection/displacement criteria of the piles considering the effect of combined loading.