Drilled Shaft Integrity Testing Comparison and Evaluation Considerations for Thermal Integrity Profiling and Cross-hole Sonic Logging-PPT Presentation

PPT Presentation

Pdf Summary

The presentation compares Crosshole Sonic Logging (CSL) and Thermal Integrity Profiling (TIP) for evaluating drilled shaft integrity. CSL, conducted under ASTM D6760, measures sonic-wave travel between access tubes and is typically performed 3–10 days after concrete placement. TIP, under ASTM D7949, uses heat from cement hydration and requires measurements near peak temperature, which often occurs 24–48 hours after placement but can vary substantially.<br /><br />In Project 1, a 48-inch shaft with a rock socket and bi-directional cell was tested using both methods. CSL showed arrival-time delays in all six profiles near the shaft bottom, with highly abnormal results from 46 to 52 feet. TIP data peaked 30.5 hours after placement and, accounting for construction details and temperature adjustments at the water and mudline boundary, indicated a satisfactory shaft with no effective radius reductions greater than 6% and about four inches of minimum cover.<br /><br />Project 2 involved a 36-inch shaft constructed through a flowing river. Initial CSL testing showed delays in the upper 14 feet and additional lower-shaft anomalies. A retest several days later showed substantial improvement, though some results remained conditionally acceptable. TIP peak temperature occurred at 85.5 hours, with different shaft sections reaching elevated temperatures at different times. The instrumented upper 59 feet was assessed as satisfactory, with no effective radius reductions greater than 6%.<br /><br />Key evaluation considerations include retesting CSL after concrete has gained strength, collecting TIP data at multiple time intervals, and using project-specific construction details to interpret anomalies. Temperature peaks may occur later than expected, and engineered features such as bi-directional cells or tube deviations can affect measurements. Integrity testing should inform, but not replace, the overall shaft acceptance process.

Keywords

Crosshole Sonic Logging

Thermal Integrity Profiling

drilled shaft integrity

ASTM D6760

ASTM D7949

concrete placement

arrival-time delays

temperature peak

shaft evaluation

integrity testing