Drilled Shaft Imaging With 2D Ultrasonic Waveform Tomography

Details

• Creators:
  Tran, Khiem ; Yang, Bingkun
• Corporate Creators:
  University of Florida. Dept. of Civil and Coastal Engineering
• Contributors:
  Shishlova, Kelly
• Corporate Contributors:
  Florida. Department of Transportation
• Subject/TRT Terms:
  Acoustic Waves Bridges Crosshole Sonic Logging Drilled Shaft Imaging Full-waveform Inversion Infrastructure Pile Foundations P Wave Velocity Quality Assurance Shaft Bearings Structural Design

  More +
• Publication/ Report Number:
  BED31- 977-27
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States
• Edition:
  Final Report: 03/01/2024 - 08/31/2026
• Corporate Publisher:
  Florida. Department of Transportation
• Abstract:
  Drilled shafts are widely used as deep foundations for transportation infrastructure; however, construction defects such as soil intrusion, concrete segregation, slurry inclusions, necking, and soft-bottom conditions can compromise structural integrity and long-term performance. Conventional crosshole sonic logging (CSL) provides valuable quality-control information but offers limited capability for imaging shaft geometry and defect extent. This study developed, optimized, and field-validated a two-dimensional ultrasonic full waveform Inversion (UFWI) framework for high-resolution drilled shaft imaging using CSL waveform data. The method combines acoustic wavefield modeling, adjoint-state inversion, and regularized model updating to reconstruct cross-sectional P-wave velocity distributions without prior knowledge of shaft boundaries or defect locations. Synthetic studies demonstrated that UFWI can accurately image shaft geometry and detect internal and boundary defects. Parametric analyses further showed that at least five CSL access tubes are required for reliable imaging, while approximately one tube per foot of shaft diameter is recommended for shafts 6 ft in diameter or larger. Field validation was conducted on a full-scale 6-ft-diameter, 40-ft-long drilled shaft constructed at the Florida Department of Transportation (FDOT) Hawthorne test facility with intentionally embedded defects, including concrete segregation, necking with soil intrusion, slurry inclusions, and a soft-bottom condition. UFWI successfully reconstructed shaft boundaries; identified major defect horizons; and localized anomalies consistent with documented as-built conditions. Compared with conventional CSL, UFWI provided higher spatial resolution and more detailed characterization of defect geometry, demonstrating its potential as a quantitative nondestructive evaluation tool for drilled shaft quality assurance and integrity assessment.
• Format:
  PDF
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:acc5b43522efb321ad12e9f0dc2d1662e1466cf0b1027a4a095023af2c7761fb9c02d1bb21667769796c8022bfc63f257994ab4f2e98226b36b9e2b87cda7a95
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/93037/dot_93037_DS1.pdf
• File Type:
  [PDF - 4.92 MB ]