Abstract:
The experience gained during more than 900 Crosshole Sonic Logging (CSL) tests on drilled shafts shows the importance of establishing proper project acceptance and repair protocols. Drilled shaft evaluation is a multidisciplinary task that should not be left solely to the outcome of the CSL test. This test allows characterizing and delimiting areas of different quality of concrete and it is important that all the parts understand the difference between flaw and defect. The information presented here is intended to give a guideline to contractors, inspectors, owners and clients on how to deal with acceptance and remediation of defected drilled shafts, detected using CSL tests. A data base of flaws is presented depending on its location, intensity and remediation method. Procedures are presented that allow the flaws to be analyzed in order to dismiss or classify it as a defect. In many cases, the CSL test may indicate an anomaly, but by coring of the concrete and analysis of the structural demands and conditions, the flaw can be classified as non-severe. When flaws are classified as defects, their repair will depend on the area where they are located on the pile. In this document two procedures are described for repairing defects depending on its location. For defects in the drilled shaft head area, the procedure takes into account the interaction between the new and old concrete. For repairing the middle zone of the drilled shaft by grouting, the major concerns are the difficulty of accessing through the drilled shaft at deep depths and the communication between boreholes. For defects in the drilled shaft tip two proposed remediation methods are presented. Finally, tomographies test are presented to compare the effectiveness of remediation by grouting.