Abstract:
With the advancement of manufacturing technology over the years, many different types of piles can be chosen to be installed to resistance specific loads based on pile performance, as well as installation time and cost. A relatively newer pile being used for load bearing applications is ductile iron pipe. The installation method of ductile iron pipe allows for very little material waste and also does not require any welding, making it a feasible financial alternative to more conventionally driven or drilled foundations. While the installation of ductile iron pipe is monitored for installation time to correspond to an allowable load, very little to no testing has been performed during the installation of these piles to obtain actual load resistances during installation and the existing correlation involves many assumptions related to long-term soil behavior, which may not necessarily be present.This case study examines a project in New Jersey which had ductile iron pipe installed by use of a hydraulic breaker, during which dynamic load testing (PDA) was performed in an effort to assess actual hammer performance, pile behavior and establish a correlation of equivalent static capacity vs. installation rate for the piles being installed. As is typical for this pile type, static load testing was performed to a limited capacity (dictated by the reaction piles, rather than actual geotechnical resistance of the pile being tested) at a later time for piles that were installed to a dense end-bearing layer, as well as to a shallower less dense layer.Furthermore, to allow to fully mobilize the soil resistance, a sufficiently large drop hammer was then used to perform restrike testing on 5 piles, resulting in much higher capacities being able to finally be mobilized, allowing for a more accurate assessment of the load-bearing capacity of the piles installed.