Evaluation of a New P-Y Analysis Tool for Lateral Analysis of Drilled Shafts Using Load Tests in Nevada-PPT Presentation

PPT Presentation

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The presentation introduces NVShaft, a University of Nevada, Reno tool for analyzing the lateral response of drilled shafts using p-y methods. It addresses limitations of conventional p-y curves, which are largely based on tests of slender piles and may be overly conservative for large-diameter shafts. NVShaft includes nonlinear static and cyclic p-y curves, corrections for layered soils, tapered and nonlinear shaft modeling, varied head boundary conditions, and the ability to include shaft-tip and side-shear resistance.<br /><br />A sample comparison with LPILE showed nearly identical predicted deflections and bending moments, providing a basic validation of the program. NVShaft was also evaluated against lateral load tests from the I-15/US 95 reconstruction project in Las Vegas. The study modeled a 2-foot-diameter, 35.7-foot-long shaft and an 8-foot-diameter, 32-foot-long shaft in soils containing dense, partially cemented sands and caliche.<br /><br />For both shafts, predictions were reasonably accurate at lower loads. At higher loads, measured behavior was softer than predicted, especially for the 8-foot shaft. The presentation attributes discrepancies partly to damage and altered ground conditions from prior axial load tests, including concrete crushing, soil heave, and radial cracking. These factors complicate interpretation of the lateral tests.<br /><br />Overall, NVShaft appears to reproduce conventional p-y analysis results and offers additional modeling capabilities. The field comparisons demonstrate its potential, while underscoring the importance of accounting for shaft condition, soil cementation, and test-induced effects when evaluating high-load response.

Keywords

NVShaft

drilled shafts

lateral response

p-y methods

nonlinear p-y curves

cyclic p-y curves

layered soils

shaft-tip resistance

side-shear resistance

lateral load tests