Three progressively larger statnamic lateral load tests were performed on a 2.59 m diameter drilled shaft foundation after the surrounding soil was liquefied using down-hole explosive charges. An attempt to develop p-y curves from strain data along the pile was made. Due to low quality and lack of strain data, p-y curves along the test shaft could not be reliably determined. Therefore, the statnamic load tests were analyzed using a ten degree-of-freedom model of the pile-soil system to determine the equivalent static load-deflection curve for each test. The equivalent static load-deflection curves had shapes very similar to that obtained from static load tests performed previously at the site. The computed damping ratio was 30%, which is within the range of values derived from the log decrement method. The computer program LPILE was then used to compute the load-deflection curves in comparison with the response from the field load tests. Analyses were performed using a variety of p-y curve shapes proposed for liquefied sand. The best agreement was obtained using the concave upward curve shapes proposed by Rollins et al. (2005) with a p-multiplier of approximately 8 to account for the increased pile diameter. P-y curves based on the undrained strength approach and the p-multiplier approach with values of 0.1 to 0.3 did not match the measured load-deflection curve over the full range of deflections. These approaches typically overestimated resistance at small deflections and underestimated the resistance at large deflections indicating that the p-y curve shapes were inappropriate. When the liquefied sand was assumed to have no resistance, the computed deflection significantly overestimated the deflections from the field tests.
College and Department
Ira A. Fulton College of Engineering and Technology; Civil and Environmental Engineering
BYU ScholarsArchive Citation
Bowles, Seth I., "Statnamic Lateral Load Testing and Analysis of a Drilled Shaft in Liquefied Sand" (2005). All Theses and Dissertations. 723.
statnamic, liquefaction, liquefied sand, p-y curves, log decrement, load-deflection curves, equivalent static load deflection curve, p-multiplier