This document provides instructions for using Cross Hole Sonic Logging (CSL) software to acquire CSL test data, edit the data, and prepare a report. It describes the steps to create a new project, configure the tubes and acquisition parameters, collect data while monitoring graphs of the signals, and process the data to produce a sonic map and analyze defects. It also explains how to trim unwanted top data, select arrival times and energy calculations, and prepare a report with sortable properties. The goal is to use CSL to nondestructively test deep foundations.
7. Data Acquisition Parameters
• National Instruments A/D card (NI PCI-
MIO-16E1
• The rate of sonic pulse generation and
averaging.
• By default it is 30 scans/second
• Time for each data record
• Data sampled at 500 kHZ
• 500 data points represent 1 millisecond
• 250 data points represent 0.5
milliseconds
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10. Understanding the Data Collection graphs, indicators, and controls
Start/Stop Referencing the Depth Encoders
TX/RX location is Bottom
TX/RX reference depth is zero
Reference depth of encoders= Total
tube length-tube length above concrete
TX/RX location is top
TX/RX reference depth is zero
Reference depth of encoders=
zero-tube length above concrete
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11. Data Acquisition Settings
Trigger Delay – TD
Amount of time that the software waits between generation of a sonic pulse and the
start of data acquisition for detecting and capturing the received signal.
TD = 106 * (tube spacing/wave speed) – 100
Trigger Delay
Arrival time relative threshold
Arrival time absolute threshold
Energy calculation range
GAIN – Signal Processing circuitry
Increase the resolution of the sonic map
display in vertical direction
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Strength of the signal
data display graph
Subtracting the 100 micro seconds off sets the arrival time by
20% for 250 data points or 10% for 500 data points
12. AT – REL - Arrival time relative threshold
The CHA detects arrival time by locating the peak value of a signal, then using a
relative percentage of that peak as a threshold for locating the leading edge.
currently recommend using a number between 20-30 as the starting default AT
AT-ABS – Arrival time absolute threshold
The CHA can use an absolute percentage of the full scale range as a threshold for
locating the leading edge.
currently recommend using a number between 10-15 as the starting default AT
ECR – Energy calculation range
ECR is simply the number of sampled data points used for integration of the
acquired signal voltage. 12
13. Profile monitor window
• Transmitter TX and receiver RX depth location
• Depth location
The data acquisition signal graph
Pile name
Tube
location and
spacing
+10 volt
0 volt
-10 volt
Peak signal value of the
data acquisition signal graph13
14. Sonic Map / Water fall diagram
• Nesting of signals at all depths
• Transmitter – Black
• Receiver – Red
• 0 volts – White
• +10 volts – Green
• -10 volts – Black
Depth
Time
Current
position of TX
& RX
Black – TX
Red-RX
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15. The Energy /Arrival Time Graph (Processed results graph)
• Arrival time = AT threshold + trigger delay (ms)
• Wave Speed = (Tube spacing / Arrival time )
C = L/FAT
• Energy is calculated by integrating the absolute value of
the acquired data over a user-specified interval (ECR -
energy calculation range) which is specified in sampled
data point counts (volt/s)
Arrival time
graph
Energy
graph
Graph shows the relative
value of the Energy
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16. The Pull-Rate Indicator
• The pulling/ lowered rate of the Transmitter and Receiver
Vertical red dashed line –
Maximum pull rate according
to the sample rate
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18. Arrival Time Thresholds , Energy Calc. Range
• AT- REL
• AT-ABS
• ECR
Vertical scale is isolated on the section of the
shaft
Activates “Image Processing edge finder”
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19. Image Processing Edge Finder
• Assist in finding first arrival
time (FAT)
Sonic Map
Processed
Image
This red line shows
the first arrival time
Between
15~30
,max 40
Sigma
Good Data =0.3~0.6
Noisy Data=Lager
Value but less than 1.2
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20. Trimming pile top
• To remove the unwanted to processed result from the pile top (due to
tubes protruding above the top of concrete)
• click on the sonic map at the location where the real data begins
• Next click on TRIMTOP and the processed result above that location
will be deleted
From Reset Current AT button, can reset
individual arrival time selections.
Manual Selection of Arrival Time
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21. Result Selection
• The processed FAT can be presented as either arrival time or wave speed.
• The processed signal can be presented as either amplitude or relative energy
(integrate).
• Clicking the Defect Analysis button creates a dialog box with user adjustable
controls.
Defect Analysis
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22. Defect Analysis Cont..
• User can determine the thresholds for ‘defects”
from setting the FAT delay and/or the Energy
Decrease.
• The two Reference Filters are the number of
points in a consecutive running average
• smaller values follow the measured signal
more closely while larger values make the line
straighter; values of 75 are a good starting
point and work for most applications.
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27. References
Pile Dynamics, Inc. Cross-Hole Analyzer (CHA) Operation Manual Version 2005.0010 Q May 2006
Comparing cross-hole sonic logging and low-strain integrity testing results , White, B., Nagy, M. & Allin ,
R.GRL Engineers, Inc., USA
http://www.pcte.com.au
Foundation Depth & Integrity System
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