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Defects in Drilled Shaft Foundations: Identification, Imaging, and Characterization. Final rept., May 2003-Mar 2005.
| 题名： | Defects in Drilled Shaft Foundations: Identification, Imaging, and Characterization. Final rept., May 2003-Mar 2005. |
| 作者： | jalinoos, f. mekic, n. grimm, r. e. hanna, k. |
| 关键词： | *Foundation-engineering; *Drilled-shafts; *Defects-.;Crosshole-Sonic-Logging-CSL; Drilled-Shaft-Foundations; Gamma-Gamma-Density-Logging; Nondestructive-Tests; Tomography-; Concrete-strength. |
| 摘要： | 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 shafts 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; and (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. |
| 报告类型： | 科技报告 |
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