| Title | Defects in Drilled Shaft Foundations: Identification, Imaging, and Characterization |
|---|---|
| Record ID | 75047 |
| Personal Name Creator |
Jalinoos, Frank; Mekic, Natasa; Grimm, Robert E.; Hanna, Kanaan |
| Personal Name Contributor |
Haramy, Khamis Y.; Anderson, Scott; Surdahl, R. |
| Corporate Creator | United States. Department of Transportation. Federal Highway Administration. Central Federal Lands Highway Division |
| Publisher | United States. Federal Highway Administration. Central Federal Lands Highway Division |
| Publication Date | 20050301 |
| Language | English |
| Abstract | This report addresses two key issues needed by the foundation engineer to assess the structural integrity of drilled shaft, or other concrete structures that contain access tubes; specifically: a) What constitutes a defect in a drilled shaft?; and, b) How to relate observed defect in a velocity tomogram to engineering strength information? This study was conducted based on the development of a three-step approach: 1) Anomaly Identification and Independent Verification - This step allows the engineer to identify and independently verify suspected “anomalies” in drilled shafts. It is concluded that both crosshole sonic logging (CSL) and gamma-gamma density logging (GDL) must be used. For velocity imaging of the shaft’s interior, three-dimensional crosshole sonic logging tomography (CSLT) is required. 2) Defect Definition – A statistical approach is presented to define a cut-off velocity to separate CSLT velocity distribution of sound concrete from the velocity distribution of anomalous concrete. The cut-off velocity is then used to volumetrically image a “defect” volume. 3) Defect Characterization – Finally, changes in velocity values in the defect volume is correlated to changes in concrete strength and a 3-D strength image is developed for integrity assessment by the engineer. The velocity-strength correlation is developed in the laboratory using cylinders with the same design mix as the shaft and allowing for maturity. Therefore, this study proposes a complete analysis and technical information to assist the foundation engineer and owner agencies in deciding to accept, remediate, or reject a given shaft or a wall structure. |
| Public Note | COTR: Khamis Haramy, FHWA-CFLHD. Advisory Panel: Scott Anderson, FHWA-FLH and Roger Surdahl FHWACFLHD. This project was funded under the Federal Lands Highway Technology Deployment Initiatives and Partnership Program (TDIPP.) |
| Rosap ID | dot:50276 |
| Rosap URL | https://rosap.ntl.bts.gov/view/dot/50276 |
| TRT Terms | Concrete; Strength of materials; Logging (Recording); Foundation engineering; Testing; Nondestructive tests; Temperature measurement; Tomography |
| General Subjects | Concrete Strength; Crosshole Sonic Logging (CSL); Defects; Drilled Shaft Foundations; Engineering Properties of Concrete; Integrity Testing; Gamma- Gamma Density Logging; Maturity; Nondestructive Testing (NDT); Temperature Monitoring; Tomography |
| Geographical Coverage |
United States |
| TRIS Online Accession No |
1751336 |
| Contract Number | DTFH68-03-P-00116 |
| Report Number | FHWA-CFL/TD-05-003 |
| Resource type | Tech Report |
| URL | https://ntlrepository.blob.core.windows.net/lib/75000/75000/75047/FHWA-CFL-TD-05-007.pdf |
| Format | |
| Database | NTL Digital Repository |