SAMPLE SPECIFICATION for CROSSHOLE SONIC LOGGING [CSL] September 2015
Note: This sample specification contains recommended or typical quantities in parenthesis, in the format [quantity];
the specifying Engineers can adapt these quantities for their particular construction projects. Contractual items are
minimized since each agency has its own preferences and procedures.
Method overview of Crosshole Sonic Logging [CSL]. By sending ultrasonic pulses through concrete
from one probe to another [probes located in parallel tubes], the CSL procedure inspects the drilled shaf
structural integrity of the concrete between the tubes, and extent and location of defects, if any. Both
the time between pulse generation and signal reception [“First Arrival Time” or “FAT”] and the strength
of the received signal give a relative measure of the quality of concrete between transmitter and
receiver. Dividing the distance between transmitter and receiver by the FAT value yields the approximate
concrete wave speed which also is a relative indicator of concrete quality. For equidistant tubes, uniform
concrete between the test tubes yields consistent arrival times with reasonable pulse wave speed and
good signal strengths. Non-uniformities such as contaminated or sof concrete, honeycombing, voids
and inclusions exhibit delayed arrival times with reduced signal strength. CSL procedures are
standardized by ASTM 6760, Standard Test Method for Integrity Testing of Concrete Deep Foundations by
Ultrasonic Crosshole Testing. Standards are also available in many other countries.
[a] Personnel requirements for CSL.
[1] Qualifications of CSL Consultant. The CSL Consultant shall have a licensed professional
engineer supervising the testing and interpretation of results. The CSL Consultant shall
be an independent testing agency with at least [3] years experience in CSL testing. The
CSL Consultant qualifications and the specifications for the equipment used shall be
submitted to the Engineer for approval prior to beginning drilled shaf installation.
[2] Assistance by the drilled shaft Contractor to the CSL Consultant. The Contractor shall
provide cooperative assistance, suitable access to the site and drilled shafs to be tested,
and labor as required to assist the CSL Consultant in performing the required tests. Prior
to testing, provide the drilled shaf lengths, tube lengths and positions, and drilled shaf
construction dates to the CSL Consultant.
[b] Equipment requirements for CSL.
Provide a Cross Hole Analyzer manufactured by Pile Dynamics, Inc., [30725 Aurora Road, Cleveland,
OH 44139, USA; www.pile.com/pdi; email: info@pile.com; phone: +1 216-831-6131; fax +1 216-831-
0916], or an equivalent CSL equipment. The equipment shall have the following minimum
requirements:
- A computer based CSL data acquisition system for display of signals during data
acquisition, with a minimum 12 bit A/D converter with a sampling frequency of at least
500,000 Hz, and recording of all pulse signals for full analysis and individual inspection.
[Note: Converting signals with low noise using high A/D resolution and sampling rates is
important to obtain quality data and allow proper full data interpretation.]
- Ultrasonic transmitter and receiver probes capable of producing records at a minimum
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