Quality Assessment of Drilled Shaft Foundations at the Jane Byrne Interchange-Paper

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The paper evaluates drilled-shaft integrity testing at Chicago’s Jane Byrne Interchange, where more than 400 shafts were installed. The authors compare Cross-Hole Sonic Logging (CSL), which measures ultrasonic signal travel time and strength between access tubes, with Thermal Integrity Profiling (TIP), which uses concrete-curing temperatures to estimate shaft shape and condition.<br /><br />During Phase I, 92 shafts were tested using CSL. Fifty shafts (54%) showed anomalous zones; 39 of those (78%) were in the lower three shaft diameters. Some severe indications near shaft toes were not confirmed by follow-up investigations. Two shafts with substantial CSL anomalies nevertheless exceeded their required capacities in dynamic load tests, illustrating that CSL indications do not necessarily imply inadequate structural performance.<br /><br />During Phase II, TIP was accepted by the Illinois Department of Transportation as an alternative to CSL. All 34 shafts tested with TIP were assessed as having expected and acceptable integrity. Unlike CSL, TIP can assess concrete outside the reinforcing cage and provide information about shaft diameter, concrete cover, and cage alignment. The authors found the methods generally comparable for identifying significant anomalies, but both have limitations in detecting minor irregularities.<br /><br />The project findings suggest that TIP may be more effective than CSL for evaluating potential issues near the bottom of tremie-placed shafts, where CSL can indicate anomalies that are not corroborated by cores or load tests. TIP also provides results sooner after concrete placement. The authors recommend future studies that compare core logs directly with both CSL and TIP results.

Keywords

drilled-shaft integrity

Cross-Hole Sonic Logging

Thermal Integrity Profiling

Chicago Jane Byrne Interchange

concrete quality

ultrasonic testing

shaft anomalies

load testing

TIP

CSL