Crosshole Sonic Logging (CSL) verifies the integrity of drilled shafts.

Drilled shafts are prepared for integrity testing by CSL during their construction, by installation of at least three tubes of 2 inch inside diameter. 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.

GRL engineers perform cross hole sonic logging with the Cross-Hole Analyzer™ (CHA) by Pile Dynamics. Starting at the bottom of the shaft, a transmitter emits an ultrasonic signal in one tube. The signal is sensed some time later by the receiver in another tube. Poor concrete between the tubes will delay or completely disrupt the signal. The GRL engineer moves the sensors (transmitter and receiver) some distance upward along the shaft and the process repeated until the entire shaft length is scanned. The engineer repeats the test for each pair of tubes, allowing for the investigation of defects both along the length and by quadrant.

GRL performs this foundation integrity test in accordance with ASTM D6760-02 - Standard Test Method for Integrity Testing of Concrete Deep Foundations by Ultrasonic Crosshole Testing