Concrete Integrity Anomalies above the Mudline in River Bridge Drilled Shafts-PPT Presentation

PPT Presentation

Pdf Summary

The presentation examines integrity-test anomalies in drilled shafts located above the mudline in rivers. It focuses on Crosshole Sonic Logging (CSL), which measures acoustic signal travel between access tubes, and Thermal Integrity Profiling (TIP), which records concrete temperatures during curing. Both methods are commonly used but require interpretation; coring may be used to investigate concerning results, though it also has limitations.<br /><br />River conditions can affect measurements above the mudline. Flowing, often colder surface water changes concrete curing and TIP temperatures. It may also influence CSL indirectly through tube debonding, concrete bleeding, or other changes in the concrete.<br /><br />Two case studies showed recurring CSL anomalies in river shafts. In a South Central U.S. project, 17 of 18 river shafts had issues above the mudline, while comparable land-based shafts did not. In a New Jersey project, all 86 river shafts showed similar issues. In both projects, anomalies were chiefly signal-energy loss and were more pronounced in cross-shaft readings than perimeter readings. Coring found some bleed-water channels, but core compressive strengths exceeded design strength. In the first project, anomalies also tended to worsen when CSL testing took place later after concrete placement.<br /><br />The presentation concludes that unusual CSL or TIP results above the mudline do not necessarily indicate defective shafts; thermal conditions can produce anomalous data. TIP interpretation in this zone can be especially difficult, particularly when CSL also shows anomalies. Test results should therefore be assessed in context, including the concrete mix, placement conditions, ambient temperatures, and timing of testing.

Keywords

integrity testing

drilled shafts

mudline

Crosshole Sonic Logging

CSL anomalies

Thermal Integrity Profiling

TIP

river conditions

concrete curing

signal-energy loss