Pile Optimization with Load Tests on Nearby Sites-PPT Presentation

PPT Presentation

Pdf Summary

The presentation compares pile design and load-testing at two nearby development sites in Brooklyn, New York: the 204 Project and the 272 Project. It reviews regional and site-specific subsurface conditions, pile installation recommendations, and test performance.<br /><br />For the 204 Project, installation criteria specified a minimum pile-tip elevation of -43 and a minimum torque of 125 kN·m (92 kip-ft) in the bottom 5 feet. At the 272 Project, the criteria were a minimum tip elevation of -45 and 95 kip-ft (129 kN·m) in the bottom 5 feet. A test pile at the 204 Project was tested in July 2022; the 272 Project included simulated test performance and an actual test of Pile 125 in October 2023.<br /><br />A key focus is the difficulty of interpreting strain-gauge data from uncased cast-in-place piles, including flighted displacement piles (FDP) and continuous flight auger (CFA) piles. Actual pile diameters may vary, with necking or bulging affecting load transfer. Composite stiffness also varies with depth due to changes in reinforcement and confining stress. Additional uncertainties arise from instrument installation, matching measured strains to applied loads, and limited testing budgets.<br /><br />The presentation recommends evaluating test data holistically. Strain should generally increase with depth; deviations may indicate changes in pile diameter. Estimated elastic compression from gauge data should be checked against calculations based on the interpreted load distribution. The tangent stiffness method can help estimate a nonlinear composite modulus, but results depend on assumptions and may fit some load increments better than others.

Keywords

pile design

load testing

Brooklyn New York

204 Project

272 Project

subsurface conditions

strain-gauge data

cast-in-place piles

FDP piles

CFA piles