详情

原文传递 Defects in Drilled Shaft Foundations: Identification, Imaging, and Characterization.

题名：	Defects in Drilled Shaft Foundations: Identification, Imaging, and Characterization.
作者：	jalinoos, f. mekic, n. grimm, r. e. hanna, k.
关键词：	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. / NOTE: Final rept., May 2003-Mar 2005. / Supplementary Notes: See also PB99-178089. Sponsored by Federal Highway Administration, Lakewood, CO. Central Federal Lands Highway Div. / Availability Note: Available on CD-ROM and in color paper copy only. Order this product from NTIS by: phone at 1-800-553-NTIS (U.S. customers); (703)605-6000 (other countries); fax at (703)605-6900; and email at orders@ntis.gov. NTIS is located at 5285 Port Royal Road, Springfield, VA, 22161, USA.
总页数：	u0814；138p
报告类型：	科技报告