Crosshole Sonic Logging (CSL) assesses the integrity of drilled shafts.
Drilled shafts are prepared for integrity testing by CSL during their construction by an installation of at least three tubes with a minimum inside diameter of 38mm. These tubes are usually attached to the reinforcement cage along the full length of the shafts. After concrete has been poured, the tubes are filled with water. In CSL, a transmitter emits an ultrasonic signal in one tube and the signal is sensed sometime later by the receiver in another tube. Poor concrete between the tubes will delay or disrupt the signal.
The Geo Civ Group engineer uses the Cross-Hole Analyzer System (CHAMP-Q) to lower the probes to the bottom of the shaft and moves both the transmitter and receiver upward in unison, until the entire shaft length is scanned. The engineer repeats the test for each pair of tubes. The Geo Civ Group engineer interprets data in the field for delayed pulse arrivals (or low signal strength) which indicate potential defects, and later reprocesses the data in the office. Results are presented in a detailed and illustrated report. Tomography analysis can be performed during reprocessing when complex situations are encountered.