Access tubes for cross-hole sonic log testing là gì năm 2024

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: [email protected]; phone: +1 216-831-6131; fax +1 216-831-

0916), or an equivalent CSL equipment. The equipment shall have the following minimum

requirements:

1. 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.)

2. Ultrasonic transmitter and receiver probes capable of producing records at a minimum

1