Use of Nondestructive Testing To Establish Installation Disturbance Zone Criteria For Adjacent Continuous Flight Auger Pile Installation on Design Build Project-PPT Presentation

PPT Presentation

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The presentation describes a nondestructive-testing program used to evaluate whether continuous flight auger (CFA) piles could be installed closer together and sooner than the project’s original requirements allowed. For a design-build project in Jamaica, Queens, approximately 1,000 24-inch CFA piles were planned. The client’s criteria restricted installation within 15 feet of a pile grouted less than 24 hours earlier, while industry guidance generally permits installation at six pile diameters after 12 hours, subject to concrete or grout being set.<br /><br />The team used Low Strain Impact (Sonic Echo) testing and added Thermal Integrity Profile (TIP) testing during the pile test program. TIP measures heat generated as grout cures and helps identify potential integrity anomalies. Two anomalies were found among nine test piles. Investigation indicated both resulted from construction issues—not disturbance from nearby pile installation. One was associated with reinforcement-cage misalignment and possible necking; the other was linked to variable auger withdrawal speeds and reduced grout volume. Both findings led to improvements in reinforcement placement, centralizer use, grout mix, and auger withdrawal and grout-placement procedures.<br /><br />The testing supported a more efficient installation sequence. Results indicated that installing piles six diameters from freshly grouted piles, and three diameters from piles cured for about 12 hours, did not affect pile integrity. Production continued with TIP testing on five percent of piles, with no further anomalies detected. The presenters recommend further TIP research to better define how pile spacing and curing time affect disturbance zones.

Keywords

continuous flight auger piles

nondestructive testing

Sonic Echo

Thermal Integrity Profile

pile integrity

pile spacing

grout curing

design-build project

reinforcement cage

augur withdrawal