Mk @MSITStore C -Program Files (x86)-Piletest.com-CHUM.chm

User Manual

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17.11.2011mk:@MSITStore:C:\Program%20Files%20(x86)\Piletest.com\CHUM.chm::/CHUM_Ma...

Table of contentsTop

Installation

Getting familiar

Getting started

Common Tasks

Options

Reporting

Advanced options

Behind the scenes

Tomography

3D tomography

Appendices A. Frequently asked questionsB. TroubleshootingC. Definitions

1. InstallationWindows XP/2000/2003/Vista: The user you log into the system must be a member of the administrators group. After you have completed the setup, the software is available for execution to all normal users.

Note: Before you can start using CHUM, you must fully charge the internal battery using the provided AC adapter until the orange LED is dimmed.

Minimal computer requirements:

� Pentium III 500 MHz

� Windows 2000/XP

Recommended

� For intensive field work: 900MHz, Tablet PC or touch-screen with outdoor visibility

Software Setup

� Insert the provided installation CD into the CD drive of your computer. The CHUM setup will start automatically.

� Follow the setup defaults to install CHUM (Usually <1 minute). In case the setup does not start automatically, double click the SETUP

icon on the CD root folder.

� CHUM software is installed to [Start]-[Programs]-[Pile Testing]

Hardware drivers setup

You only need to install the hardware drivers on the computer that is used for testing. You may, however install it to the office PC, and connect the CHUM system to it.

� Plug the CHUM USB connector into the computer

� The green LED on the CHUM panel will blink ten times and then stay on.

� On your computer screen you will see the "found new hardware" balloon, and the "Found new hardware" Wizard should open

automatically

� Follow the wizard’s instructions: Insert the CHUM CD to the CD drive of your computer and press [next]

� The Wizard will start copying the driver files from the CD

� On Windows XP, a security warning appears. You may safely press [Continue Anyway] CHUM’s driver is fully tested and will not

impair your system’s stability!

� After the files are copied, close the wizard by clicking [Finish]

2. GETTING FAMILIARThe CHUM system consists of the following components:

� CHUM instrument

� A pair of depth meters pulleys

� Two depth cables: A simple ("I") type for normal CSL use and a double ("Y") cable for tomography

� Two ultrasonic transceivers (each is emitter and receiver)

� Computer (Not provided)

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� AC power adapter

� 12 V DC car battery adapter (Optional)

CHUM instrument contains the following inside the rugged housing :

� Battery: The CHUM uses a Lithium-Ion battery, 11.1V 4.4 Ah that offers high capacity and improved performance enabling up to two

days of typical use. The battery has almost no "memory" problems, and does not need to be discharged periodically. The battery has

almost no loss of power while in storage, and requires no maintenance.

� A microcontroller, data conditioning, processing and acquisition circuits.

� CHUM connector panel. The respective connectors and controls on this panel are from top to bottom:

1. Power (from either AC or car battery source)

2. USB – When plugging the USB connector to a computer, the system is turned on.

The USB cable can be pushed in or pulled out in order to best fit the computer's USB port location.

3. Green LED

� ON to indicate all internal power supplies are OK

� Blinks 10 times at 2Hz when the unit is started (USB plugged into a computer) – indicating the firmware is OK

� A faint blink every ~3sec when the system enters suspend mode (after 30 seconds of inactivity) – the suspend mode

saves battery life and the system resumes automatically when needed.

� A short blink for each transmitted pulse

4. Orange LED

� ON to indicate charging circuit is OK

� Blinks to indicate intermittent charging (empty battery)

� Lights bright to indicate continuous charging

� Dims down when battery is fully charged

5. Emitter socket

6. Receiver socket

7. Depth meter socket

� Hardware features

1. Automatic gain control: CHUM has 8 gain levels, from X1 (5v), to X512 (~10mv). The gain is adjusted automatically to

acquire the maximal number of bits without saturating the A/D acquisition card

2. Excellent signal to noise ratio:

3. Low power consumption

4. Automatic Suspend mode

Depth meters: Both contain a bi-directional rotary encoder. The encoder generates an exact number of pulses per revolution and should be

self-calibrated.

Two Transducers and Cables: The dual-purpose transducers contain piezo-electric ceramic elements that generate signals of 50 kHz (nominal frequency). Each transducer can function as either emitter or receiver, depending on the socket it is plugged into

Each transducer is attached via a pressure-proof connector to 50 meter polyurethane-coated cables wound on a reel. The cables may also be ordered in lengths of 100 or 150 meter. Other lengths are available upon request.

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3. Getting StartedSwitch on the computer, and wait for the Windows main screen to appear.

Make sure that the emitter, receiver and depth cables are connected to the panel.

Plug the USB cable into the computer.

Start CHUM software. The CHUM main screen will appear

Click [FILE] and then [NEW PROJECT] buttons (or the blue "Start a new project" link, or the left icon) link, then choose the name (or number) of a new project. For this lesson you may use the name "TEST".

Optionally enter any suitable text on the TITLE and SUBTITLE lines.

Important: Before testing your first pile, you must calibrate the depth meter See Depth Calibration

Press the big plus [+] button to start testing a pile

3.1. TestingFrom CHUM's main screen, Press the big plus [+] button to activate the pile screen

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The test wizard consists of several stages:

Pile details and geometry

Define_tube_distances

Leveling the transducers

Start pulling

Logging

Analysis

To move between the test phases, click the [Next] and [Back] buttons. If a button is grayed out, CHUM needs more information to move ahead, or does not expect the button to be pressed at this stage

The pile name/number is displayed on the window caption.

3.2. Pile details and geometryIn this screen (Above), enter information about the whole pile (not specific to profile): the pile name, sub-site, and diameter, access tube layout and level. You may also enter pile specific notes (e.g. "pile top needs trimming")

The pile (or element) name may be up to 20 characters long and may contain any character

Sub-sites are a convenient way of breaking up a big project into smaller units (Read more…). Select an existing sub-site, or create a new one by pressing the [New…] button

[Save] exits the wizard and saves all changes and all details. Changes are also saved automatically after each log is taken

[Save compact] Only arrival time and energy are recorded in the files. Files are tiny but no FAT picking can be done after they are saved, and no waterfall presentation can be done (The ASTM standard may require it)

[More ��] Opens advanced pile options

Cut all – Cuts the all profiles top (tube-stick-up) so that profiles will have the same length

Report – prints a report for this pile only. Which is convenient for on-site printing. To produce a detailed report, see Reporting

Edit tube distances – see Define tube distances

Consult with piletest.com – Send this for getting a second opinion from Piletest.com

3DT – Perform three-dimensional tomography (Optional CHUM component)

The drop-down menu above the pile scheme enables you to choose one of many available schemes you may be going to test. You may choose among:

� A pile with up to 4 access tubes named N, S, E and W respectively

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� A pile with 2 to 15 access tubes numbered 1...N clockwise (1 is Northernmost by convention)

� A straight diaphragm wall element (barrette) with up to 6 access tubes

� A diaphragm wall element with 6X2 tube arrangement

� A pile with a single access tube (AKA single hole test)

After you have selected the scheme , you can rotate using the [��] and [��] icons to the correct azimuth. This only effects the reporting and has no other meaning.

There are several ways to specify the profiles you want to test:

Fastest: Click on the [ALL] icon to define all combinations. After you have finished testing you can use the [Clear Untested] button to remove the redundant combinations only.

Coolest: Using the stylus, draw a line between the tubes (You can specify more then one profile in one broken line). To specify single-hole tests, draw a circle around one of the tubes. This input is very convenient when using a stylus (as opposed to a mouse)

Advanced: Click on the small [+] button below the profiles list to show the new profile screen

You may enter any name, but only names made of two tube letters/numbers will appear in the scheme graphics. Other profile names will be reported, but cannot be assigned to tubes.

Please note that the profile letters/numbers have a significant meaning when performing Tomography

Tested profiles are painted with a thick, red line, this way you can always see which profiles are still untested.

To delete a profile, either:

� Select it from the list and press [X]

� Re-draw over it

� Press [Clear untested] (if the profile was net yet tested)

If the profile was tested, you must confirm the delete

� TIP: Under normal conditions, piles should be tested at a concrete age of around seven days. Testing should not be performed earlier

than 2 days after concrete placement, as the curing process may be slower in certain areas. Also, tube de-bonding (separation of tube from concrete, in plastic tubes) becomes more likely as time after concrete placement increases. For this reason, interpreting the data may become much more difficult if testing is performed, about two weeks or more, after concrete placement.

� TIP: For CSL testing, the pile to be tested has at least two embedded access tubes. The diameter of the tubes should exceed the

transducer diameter by at least 10 mm, and they should be checked for clearance throughout their length. The tubes should have been filled with clean water either prior to or soon after concrete placement.

Place the depth meters on top of two of these tubes, and lower both emitter and receiver all the way to the bottom.

Click on the profile to be tested (or highlight it and press [Next]) and the leveling screen will appear.

� TIP: It is possible to press [Next] before lowering the cables, this will let you monitor the approximated tube length

3.3. Define tube distancesThe ASTM standard requires all tube distances to be reported.

For tomography, tube distances MUST be entered

To enter tube distances, select "tube distances: [EDIT]" and enter the center-to-center distance for each tube pair

When enough tube pairs have been defined, you may use [Auto complete] to automatically calculate the position or all the other tube pairs. This is useful for a large number of tubes

For example, in a four-tube pile, 5 of the 6 combinations must be entered to calculate the sixth, but for a 10-tube pile, only 18 of the 45possible combinations must be entered, and the rest can be calculated.

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�TIP: it is advisable to add some redundant measurements for cross-check. The algorithm will report the maximal error in this case.

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3.4. Leveling

Testing is done by pulling from bottom to top. Before you start pulling, you should make sure that both transducers are at the initial test position: At the same level, and as close to the bottom of the access tubes as possible.

On this screen you can see the following items, all designed to help you bring the transducers to the initial test position.

� To the left, a black strip that scrolls from the bottom to the top of the screen, showing the relative signal strength (thickness of the strip)

and the first arrival time (FAT).

� A thin line on the left is also indicating the FAT, but is heavily filtered and reacts slower to changes. The combination of the fast and

slow moving indicators gives a clear sense of the direction of change.

� On the lower right hand side an oscilloscope windows, showing the signal shape, strength (gain) and automatically picked FAT

(triangle).

TIP: Double-clicking the oscilloscope window maximizes and restores it. The window can also be moved and repositioned

� A distance meter, giving the approximate distance between the transducers (in feet or meters).

If you intend to run tomography on this profile, check the [ ] Do Tomography. You must enter the tube distance for tomography.

Select the sample duration (500, 1000, 1500 or 2000 �s) which best fits the current profile distance.

If FAT is not picked up correctly, click the [FAT options] button to show the FAT options page

Click the [Options] button to change general options (Sample spacing, unit system and profile compression) using the options page

If you are lowering the transducers while in this screen, depth from top (H) is displayed, click on the depth label to reset it.

Using the controls

While in the leveling screen, move any of the transducers up or down, in order to bring them to the same level. This is accomplished by observing the following indicators:

The black strip being closest to the left hand side of the screen and also the widest.

The signal on the Scope window is strongest (low gain).

Distance on the meter is minimal (This should be roughly equal to the measured distance between the tubes).

�

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TIP: Always level the transducers in a clean concrete zone. If the pile has a soft bottom, perform the leveling a few feet (~1m) above

the bottom, and only than lower both cables carefully together to the bottom before continuing

Having satisfied the leveling criteria, click [Next], and the pulling prompt will appear.

3.5. Start PullingDo not use the [Next] button, CHUM will move to the next test phase when you will start pulling

TIP: Select the "use sounds and voices" option to have the "pull" command spoken to you using the default system voice. See

Options

At this stage start pulling both cables together, hand after hand, as smoothly as possible until both transducers reach the top. The rate of pulling should be no more then 40 samples per second, if the vertical spacing is set to 5cm, this will be up to 2.0m/s (which is very fast)

3.6. LoggingThe data collection screen is very similar to the leveling screen except for a vertical depth axis along the signal strip on the left side of the screen, as well as no distance (between transducers) presented in the meter area.

The plot will scroll upward as the cables are pulled up. In suspect areas of concrete, The transducers can be raised and lowered in suspect zones to increase the number of data points taken. The plot of the signal strength will scroll along up and down as the cables are pulled up and down.

Suspect zones will be noticeable when the strip is thinner and/or when the left edge of the strip is further away from the depth axis (increase in

FAT). When you have finished pulling, click the [Next] button, The profile will be automatically saved, and the Analysis screen displayed

When tomography is performed, this screen has some additional controls, and pulling is performed in a special way. See Tomography

�

�

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3.7. AnalysisAt this stage, the results of the test are displayed on the screen as shown below. There a few options for this display, and the "Lines Plot"

mode is the most common. In this form, the first arrival time (FAT) and the attenuation registered at the receiver are shown as a function of

depth. A local increase of FAT or attenuation may indicate an anomaly.

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Controls description from top to bottom

The profile name (34 above) can be changed

Profile specific notes may be entered (e.g. anomaly at 3.5m)

[Presentation] Change the presentation mode

[<] and [>] Move to next/previous profile

[<<] and [>>] Move to next/previous pile

[+] and [-] zoom in and out

[ Filter=n ] FAT and Energy filtering (0 = no filter, 5=heavy filtering) (Read about filters)

[ More �� ] show advanced options menu:

� Save as CSV (Excel data format) - Compact or detailed

The profile is saved in CSV format (Plain text format with comma delimiter) and Excel (or any other associated application) is launched

Detailed file contains full waveform information. Read about using this feature

� Cut to length - enter a length to which to cut from the top of this pile. Useful when the access tubes are sticking out of the concrete in

different levels.

� Wave Speed Calculator – A simple test method for accurately measuring the wave speed read more…[��] remove the top or bottom of the profile log

� Erasing the top of the log is sometimes used if the access tube are raised much higher then the pile top surface

� Erasing the log bottom may be used if the cables were pulled with too much slack, but should usually be avoided.

[FAT] start the FAT utility form to analyze the data more thoroughly,

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[Clear] Delete the data you just collected (Warning: You will have to redo the test!)

4. Common Tasks

4.1. Start a new projectFrom the main menu, select [File]-[New project]

Verify that the "Home folder" points to the correct path, or click [Home Folder] to change it

Enter the project's name or number and click [OK]

CHUM will create a new folder under the home folder, and will create the file PISA.PROJECT

�� TIP: Use project numbers, rather than names. This makes finding and managing many projects simpler

4.2. Open an existing projectIf the file was created or opened recently, you will find it in the "most recently used" list under the "file" menu

From the main menu, select [File]-[Open project]

Verify that the "Home folder" points to the correct path, or click [Home Folder] to change it

Select the project and click [OK]

4.3. Save a projectThere is no option or need to save a project, all changes are saved immediately.

4.4. Transferring project files to another computerOn the first (or only) visit to the site, connect the computers, and copy the whole project's folder to the target (This can usually be done by dragging the project's folder)

On future visits, sort the source folder by date, and only copy the latest added files to the target computer.

4.5. Send piles over e-mailIf the files are small, you may send them as an attachment. Compressing the files with WinZip or a similar program is recommended. Note that many mailboxes cannot accept large attachments.

The simplest and best way to send a pile to piletest is using the Consulting Wizard

4.6. Change the location where projects are savedFrom the open, or new project pages, select [Home folder], and select the folder where you want your projects to be stored and where the Open Project page looks for existing projects.

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See also: Projects, Sub-sites and files

5. OptionsThe options page [Tools]-[Options] consists of two tab sheets: Logger and General

5.1. Logger options

[Vertical spacing] is the spacing between samples. A typical general-purpose value is 5cm (2"). A smaller spacing will give a finer coverage of the cross profile, but will produce larger files and will limit the pulling velocity (limited to 40 samples per second).

[Default Filter] defines the initial filter value for new piles. The recommended value is 1

[Velocity calculations] defines the algorithm used to calculate apparent velocity

� Simple: Velocity is calculated by distance/arrival time

� Advanced: distance and arrival time are corrected to compensate the distance and time the wave travels in the water within the

access tube, resulting in a higher and more accurate velocity.

[FAT options] opens the FAT options dialog

[Signal classification] opens the signal classification dialog, where you can assign one of three categories to a pulse based on velocity and

attenuation changes

5.2. General options

Units: Select if the system is using Metric (m) or English (Feet and Inch) units

Software keyboard: Check this option to have automatic screen keyboard popup when an alpha-numeric input is required. This option is only useful for keyboard-less computers

Unit Code: Changes the first character prefix of new generated pile files (e.g. the 'A' in A0002782.9_2.PILE) If you have more than one CHUM unit, assign each unit a unique code ('A', 'B', etc.) to avoid name collisions which might otherwise happen if the same project is being tested by several CHUM units.

(See also Projects, Sub-sites and files)

Use Sounds and Voices: Disable or enable voice instructions. CHUM is using the default Windows voice, accessible via [Control panel]-[Speech]-[Text to speech]. You can control the voice personality and speed.

5.3. Depth Calibration

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CHUM is using a digital depth meter producing an exact number of pulses per pulley rotation.

Depth calibration is determining the number of those pulses per length pulled. This number is internally stored in the test computer.

You should perform depth calibration:

� Once before starting to test your first pile

� When starting to use a new computer

� Once a year

� Whenever there is a doubt regarding the depth reading

To perform depth calibration, simply select [Tools]-[Depth calibration] and follow the wizard,

Verify repeatability by re-running the wizard.

For your reference, here is an extract from ASTM 6760-08 (Standard Test Method for Integrity Testing of Concrete Deep Foundations by Ultrasonic Crosshole Testing)

6.3.6 Transducer Depth-Measuring Device ... The depth-measuring device shall beaccurate to within 1 % of the access duct length, or 0.25 m,whichever is larger

5.4. Signal classification optionsFrom the Options Logger tab, select signal classification, to open this page

The signal classifications are used to color-code a pulse based on velocity and attenuation changes. This is also used for real-time and fuzzy-

logic tomography, control the values that classify a pulse into one of three color-marked categories. Those can be called "good", "questionable" and "poor", but they are really just two logic criteria options, as depicted below

You can control the area of the three zones, and change the logic operator ("AND" / "OR") as well as to ignore attenuation altogether, and use just velocities.

5.5. FAT Picking optionsThe FAT (First Arrival Time) picking options can be accessed from the main menu (Tools-Options), from the leveling page, or from the FAT

utility

Four options for picking the FAT are available, each method uses different settings:

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Piletest highly recommends the use of the "Automatic" algorithm.

Dynamic threshold:A Piletest.com algorithm which uses a threshold level based on the pulse amplitude

Minimum Time: You can set this limit so that the signal picking routine will not look for a shorter FAT. For example, a delay of 200 �Sec will

cause all FATs to be 200�sec or higher. Please note that this time should be sufficiently lower than the minimum wave travel time between

the tubes for normal quality concrete. Example: 250�sec for tubes 3 feet apart and a typical 12,000 ft/sec concrete wave velocity (t=L/C).The minimum time is represented as the horizontal position of a small red triangle.

Threshold Ratio: This is a limit that is referenced to the pulse amplitude. In general, a higher ratio means that the program will pick FATs sooner, but is also more sensitive to noise. The signal is typically strongest in the earlier portion of the record after the first few peaks. A ratio, for example, of 10 means that the first occurrence of a signal amplitude 1/10 of the maximum is defined as the FAT. Typical value is around 10 to 20, but under poor test conditions, lower values may be required.

Minimum Level: This is an absolute limit that does not depend on the background noise level. If the threshold is lower than say 10 mV, then anything lower before the first 10mv peak will be ignored. This option is rarely needed and may usually kept 0, it comes into effect in very week signals and is mainly kept for backward compatibility

Fixed threshold:Old-Fashioned picking, threshold value is fixed.

Automatic:A Piletest.com proprietary algorithm, no additional settings are needed.

Read more here for algorithm explanation.

STA/LTAStands for "Short Term Average / Long Term Average"

Description:

A window of defined size is moved along the time axis and measures the average of samples in this window.

Another window of larger size follows the first one

FAT is defined as the earliest point where the ratio between the two averages exceeds a user-defined ratio

Typical values are:

Window size: 6

Ratio: 1.6

ref: Caltech Earthquake Detection and Recording (CEDAR) system [Johnson, 1979].

To learn more - Enter "STA/LTA" to your web search engine.

5.6. PresentationThe presentation window is accessible from the Analysis page, or from the Report page.

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You can select the presentation mode among the currently available methods:

� Line Plot, with a combination of the following curves

� FAT [micro seconds]

� A colored flag at FAT+20%

� Either Relative energy [unit-less] or Attenuation [dB] - but not both

� Apparent velocity [m/s of feet/s]

� washed-out Waterfall background

(Note – the ASTM standard requires that waterfall presentation will be added if any filtering is used)

� Dual

� Waterfall

� Fuzzy logic tomography (*)

� Parametric tomography (*)

* - Only if the data was collected with diagonal readings using two depth encoders (Tomography)

Color - select the color for the presentation. When selecting a color, consider your final report capabilities:

� Can your printer print in color or in gray shade

� Is the report going to be faxed? most faxes are B&W only

6. ReportingThe reporting options are divided between three tab sheets

Report contents

Filtering

Layout options

Once you click [OK], a report file called report1.rtf is generated and your assigned word processor is started on it. You can then edit the report, merge it with other documents, e-mail it, etc.

See also: [Page setup dialog] [Report style]

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Check [X] Project Totals to produce a table specifying the number of piles and profiles and the total length of piles and profiles for each sub-site

Check [X] Project Summary to produce a table stating the measured length of each profile, and related comments recorded with it.

[ ] Site Plan is not yet implemented

Check [X] Detailed report to produce a table for each pile, including graphs and all recorded details, the [Options] tab is only available if this option is checked

You may select to report all piles, piles from the latest month or from the latest visit.

If a pile is selected in the main page, a fourth option is displayed for reporting only the selected pile

Check [X] Include non-tested piles will include piles which have no recorded logs in the final report.

This tab is only available if [X] Detailed report is checked

Vertical scale can be set to a specific value, or set to [Automatic] to best fit the page height

In "Automatic", the scale is calculated to fit the longest profile in the report to one column. Smaller scales may cause some profiles to be printed over several columns.

Number of columns (one graph per column) can be set. It is recommended to switch to landscape print orientation when using more then 3 or 4 columns

Presentation mode can be selected for the whole report

"Distortion" is only enabled for a tomography report, and will improve the visual presentation of piles by distorting their width relative to height.

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� TIP: You cannot mix several presentation modes, scales, etc in one report. You may, however, achieve this by cutting and pasting two

separate reports

6.1. Controlling the report styleFrom the main menu, select [Tools] – [Style] to show the style screen

Select an item from the list on the left hand side and change its appearance using the controls on the right side.

[x] Use: Include or exclude items from your report.

[Default]: Restore the style for all items to the factory settings

[Close]: Done. Try your new style by producing a report

�� TIP: You may select several items from the list on the left by pressing the [shift] or [control] keys while pointing on items. This way you

can change the appearance of several items together.

�� TIP: underscores (_) are converted to spaces. Append a few underscores to your prompts to unsure proper tabulation of titles labels

and values.

�� TIP: Avoid using too many font styles in your report; a good-looking report usually uses two to three font styles at the most.

6.2. Page setupFrom the main menu, select [File] – [Page Setup] to show the following screen

Your currently selected printer name is displayed on top, and you can control the margins size on each side of the report page (mm)

7.Advanced options

7.1. Enable/Disable featuresFrom CHUM's main menu select [Tools]-[Enable/Disable features] to activate the features manager.

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The checklist represents the enabled features. By default, all features are enabled, and you may choose to disable some for one or more of the following reasons:

� To simplify the use of CHUM by hiding features you never use.

� To limit the amount of control you give the field technician.

� To prevent possible operation errors in the field

� To enforce a specific usage pattern on your team.

If you wish to protect (to some degree) the changes, you may select a password. After you select a non-empty password, you will be requested to re-enter it each time you start the feature manager.

�� Tip: If you forgot your password - look it up in the file CHUM.INI, stored under your user’s "application data" folder

Note: There is no way to really protect this password from malicious users.

�� Tip: To remove the password, set it to empty.

7.2. First Arrival Time (FAT) PickingFrom the Analysis screen, press [FAT]

This dialog is split into two panes: Left pane: the FAT vs. depth plot. Right pane: the actual signals.

Note that the vertical position is referenced from the bottom of the tubes rather than the top of the tubes. This is because the data is collected from the bottom up. When you leave the FAT signal picking screen, the software re-plots the depth from the top.

The vertical separator between the panes can be dragged right or left

The horizontal separator between the signals on the right pane can be dragged up and down

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In some cases, the FAT will not be selected correctly by the software. This tool is powerful for manually adjusting the automated FAT signal picking routine performed by the software. There are two major methods available for picking the FAT signals by yourself; manually or automatic.

Manually: Click on the signal trace on the right hand side of the screen. A highlighted signal will be shaded. Please note that a small circle will appear on the left side highlighting where the particular signal is in the plot. Remember that in this screen, vertical position is from the bottom. You can directly pick the FAT in the signal by moving the mouse to the point where you think it should be and then click the left mouse button. The FAT will be delineated by the two diagonals intersecting at the FAT on the horizontal (time) axis. The time of the FAT (in Microseconds) will be shown in the data area. The highlighted circle in the depth plot on the left will move accordingly depending on where you selected the FAT on the signal plot on the right. Additional data such the depth (in meters/inches) and scale are also shown in this area.

Automatically: This option is very powerful as it can change the FAT for all applicable signals along the pile. Click on [Calc] to enter the

automatic FAT picking menu.

Once you have selected the values, click on [Close]. The program will then recalculate all of the FATs for the entire profile. You will see a change in the plot of the individual FATs. If you agree with the FATs, than click accept. Click [Cancel] to go back and ignore any changes.

The last button in the FAT signal picking screen is the [Actions ��] button. Use this to:

� Change the view of the signals, You may view the raw data and/or the filtered data and/or the signal envelope

� Delete / undelete any signals that you have highlighted on the right.

� Restore all previously deleted signals (as long as you have not left the FAT signal picking screen).

� Copy the highlighted pulse shape to the Windows clipboard. You may than paste it into your report

7.3. Consulting with Piletest.comFrom the Pile details page, select [More��] and [Consult]

Piletest.com offers limited consulting services in order to:

� Help novice testers with analysis

� Help advanced users with difficult cases

� Collect interesting test cases

The "Consulting Wizard" opens

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The consulting wizard lets you select the profiles of the pile that will be compressed. The tradeoff is yours:

� Compressed profiles contain no waveform data and no FAT picking can be done, but the profiles are very small in size and can be

transferred quickly

� Non-Compressed profiles contain full waveform data and Piletest.com can observe and modify the FAT pickings. But such profiles are

much larger and take much longer to transfer. If the whole file size is below 20Mb, and you do not have any bandwidth limitations, send the file uncompressed

The wizard provides an estimate of the file size and the expected transfer time. Files will first be transferred to Piletest.com's web storage (by

FTP). Next your default e-mail editor will be opened with a message to [email protected] - please provide clear information about the consulting you require.

7.4. Data SourcesCHUM can accept data from several sources. This allows the same software to run in the field and on the desktop computer for training and demonstration purposes.

From the main menu, select [tools] – [Data source] (or the wrench icon) to show the following screen

Data sources that are built-into CHUM are

The currently selected data source is displayed in the window title.

To change a data source - select one from the drop-down list.

Name Description

USB Connects to the CHUM hardware via USB, in order to test piles. In the field CHUM should only select this data source

Demo Uses simulated pulses with one simple defect

Replay Replays a stored profile from any pile (Advanced)

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To test the currently connected data source, press [Test], the dialog will expand to show the data source diagnostics

In this mode, CHUM triggers the emitter at 10Hz and displays the following parameters:

� The data source description

� Tomography supported / not supported

� Hardware status and error codes

� Depth encoders raw counters readings for both counters (ignore the second reading if you only have one depth encoder)

� Sample rate (Should be 500 KHz)

� Battery voltage.

� The automatic gain picked for the displayed signal

� Attenuation for the received pulses

Press the [Stop] button to exit the self-diagnostics mode

7.5. Exporting data You may export profiles stored in CHUM internal format to a CSV (Comma delimited) format. CSV is a text format recognized by most spreadsheets (such as Microsoft Excel).

To generate a CSV file, start CHUM and select the pile and profile you want to export, then click [More] and select either a detailed, or a compact file formats

Compact CSV contains the profile details, and the individual pulses FAT and Energy

Detailed CSV contains, in addition to the compact data, each of the pulses shape.

CHUM now asks you for a filename and location to store the CSV file, the default file name is <pilename>.<profile name>.CSV, for example if you save profile NS of pile 3-1, the default filename suggested is 3-1.NS.CSV:

Once you saved the file, CHUM will try to launch the associated application (such as Excel), if this does not work, start your spreadsheet application and open the saved CSV file.

NOTE: If you get a "file not loaded completely" message, simply ignore it.

Cells description

A2..F2 Project name, Pile name, Profile name, Filter, tubes distance (cm), profile notes

Row 3 - Samples headings:

Column Title Description Units

A D1 Master (or single) depth encoder readings cm from bottom

B D2 Secondary depth encoder readings (identical to D1 if not tomography was done) cm from bottom

C T0 FAT microseconds

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* To convert the pulse value to volts, use the following formula

Volts = Value * 5.0 / (2048 * gain)

Generating a curves chart

(Specific to MS Excel)

� select B4..D4

� Press CTRL+Shift+Down to select 3 columns of data

� Press the chart wizard icon

� Select X-Y scatter without markers

� (Optionally) swap X and Y axis and add titles and labels

� press [Finish]

Extracting a single pulse shape chart

(Specific to MS Excel )

Only available if a detailed CSV file was saved

� select Hn (where n stands any row, for example H4)

� Press CTRL+Shift+Right to select the whole row

� Press the chart wizard icon

� Select X-Y scatter without markers

� (Optional) specify titles and labels

� press [Finish]

D Energy Total energy of the pulse mV.��s

E SampleRate A/D sampling rate (samples / second) Hz

F Gain AGC (Automatic Gain Control) value * -

G Number of samples how many samples are taken for one pulse Samples

H... Value(n) Pulse shape data, 12-bit value (-2048..+2047)* Bits

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7.6. Wave speed CalculatorThe velocity calculator uses the standard test wizard, but testing is done as follows:

� Lower both transducers together to exactly the same level. This level should be in the middle of the pile, at the bottom of a 4-5m (10-

15') zone of uniform concrete. This is the tested sample.

� Define a profile in the pile, and press [Next] to start testing it, just like in a standard test

� Set sample size to maximal (2000us)

� Leave the passive transducer stationary, and raise only the transducer connected to the depth pulley. Watch the scope window and

keep pulling until the signal becomes too weak and FAT picking is no longer possible

� Press [Next] to show the profile, this should show something similar to this:

Use the [��] (scissors) icon to trim the top or bottom part of the profile, keeping only the part where the FAT pickings are reliable.

Enter the exact distance between the test tubes.

Select [ More �� ]-[Wave Velocity Calculator]

The velocity and R2 (coefficient of determination) are replacing the profile notes, e.g. "Velocity=4200m/s, R^2=0.998"

Internally, CHUM is using a linear regression on the distance vs. FAT vector; the slope of the trend line is the wave speed.

Advantages over laboratory test of a concrete cylinder sample:

� Intuitive

� Large sample size: on samples close in size to the wavelength, the wave speed is different than the one in a real pile

� Averaging many samples, eliminating intermittent noises

� Affordable: No special equipment or test method is needed

� Independent of constant delays

� Good indication of the test reliability (R2)

8. Behind the scenes

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8.1. Projects, Sub-sites and files

8.1.1.BackgroundCHUM uses one dedicated folder to store all projects, this folder is called "Home folder", by default this is "C:\Pile testing"

Projects are stored as sub folders of the home folder

Each pile (All profiles) is stored as a separate file (with the extension .PILE) under the project folder.

A project folder also contains a file called "CHUM.PROJECT", which is a text file storing the project's titles and other miscellaneous settings.

A pile's file is consisted of a unit code, a system-wide unique number, the digested pile's name and the extension ".pile". For example, the pile 123** will be stored under B000059.123__.PILE

� B is the unit code (Only relevant for users with more than one CHUM unit)

� 000059 means this is the 59th pile stored on this system

� 123___ is the pile's name, with underscore (_) replacing characters that cannot be used in a filename

� .PILE is the file extension

This naming scheme makes sure that no two piles will ever get the same file name, and no test work will get overridden and lost

For example:

C:\PISA_PROJECTS <-- Home folder├───1003 <-- A project│ ├───A00059.A100.PILE <-- A pile│ ├───A00060.A101.PILE <-- Another pile│ └───CHUM.PROJECT <-- Project's settings│ :│ ├───1004 <-- Another project:

8.1.2.Sub-SitesSub-sites are a way to "break up" a project into smaller parts, which are easier to manage and can produce a clearer report.

For example: if the project contains several buildings, each building can be used as a sub-site. Piles on different buildings can have the same names.

When a project is opened, piles are grouped by the sub-site stored within each pile.

When the last pile of a sub-site is deleted or moved to a different sub-site the sub-site is removed. Sub-sites are never empty.

A new pile in a new project is created in the "default" sub-site. This name will not appear in the report. If you create a new pile in a new sub-site, CHUM will suggest you to rename the "Default" sub-site to a more meaningful name, to avoid confusion.

8.2. CHUM filters

8.2.1.Signal FilterSignal filter is a hardware band-pass filter applied to each collected signal before it reached the A/D/

Signal filter is hard-wired with no user control.

The picture below shows a signal before (gray) and after (green) the filter is applied to it. It is clearly visible that the lower frequency noise at the left side of the signal was significantly reduced allowing an accurate FAT picking.

8.2.2.Profile FiltersProfile filters are three different algorithms applied to the whole profiles of picked data points (FAT and Energy) before they are presented. The user can control these filters by selecting a single filter value F of 0 to 5, where 0 denotes no filter and 5 denotes maximum filtering.

The three filters are: Median filter, Running averages filter and delay filter, the first two are based on the fact that the theoretical vector of measurements is convoluted by relatively large kernel (exact size is determined by the pulse shape and transducer geometry), the delay filter is based on an a-priori knowledge stating that arrival times significantly lower then the expected arrival time are impossible.

Median filter: Replace each value in a vector with the median value of its neighbors:

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Ai <-- median of (Ai-k, Ai-k+1, … Ai-1, Ai, Ai+1, … , Ai+k-1, Ai+k)

Where k equals the filter value F.

Running averages filterReplace each value in a vector with the average of its neighbors:

Ai <-- (Ai-k + Ai-k+1 + … Ai-1 + Ai + Ai+1 + … + Ai+k-1 + Ai+k) / (2k+1)

Where k equals the filter value F.

Delay filter:

Find the N percentile arrival time T when N=F * 5("5" was found experimentally)

Set all arrival times lower then T to T

Examples:

If filter=0, N=0, thus T is the 0 percentile (Minimum) arrival time and the filter does nothing since no time is lower then the minimal time

If filter=5, N=25, thus T is the 25 percentile arrival time, which is usually the normal arrival time of the profile.

The following table shows the save arrival times vector with three levels of processing: without any filter, with a low filter (F=1) and with the maximum filter (F=5):

1 - Noise removed by the median filter

2 - Noise removed by running averages filter

3 - Noise removed by the delay filter

8.3. What is "Attenuation"? Energy is the amount of energy that arrives to the receiver for each transmitted pulse. Since the transmitted energy of the signals is approximately constant, it is also expected to be approximately constant at the receiver.

When a defect in the tested medium blocks the signal, it absorbs some (or all) of the transmitted energy, and a lower value is read at the receiver. Some defects (such as necking) can significantly reduce the received energy but not to change the first arrival time (FAT) since a direct path between the transmitter and the receiver still exists.

Energy is calculated as the sum of the absolute voltage values along the received pulse:

E = sum ( |Vi| )

Attenuation is calculated at

F=0 F=1 F=5

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A = 20 * Log10(C / E)

Where:

A - Attenuation [dB]

E - The received energy

C -A constant value representing the maximal possible value of received energy

Hence, Attenuation of ~6db means the received energy is about half the maximal possible value.

Since the scale is logarithmic. A shift of ~6db from the normal attenuation value recorded within a profiles means the energy drops by ~50% at this point and a shift of ~12db means the energy drops to about a quarter.

The Chinese standard defined a suspected anomaly as a 6db attenuation increase relative to the normal received attenuation. This assessment must be backed up by some FAT increase.

8.3.1. How does the energy change with regard to distance?In a homogeneous medium, the signal attenuation can be calculated according to the following formula:

Er = Et * exp(-k * x *f)

Where:

Sometimes, it is interesting to find out the change in distance needed to half the energy of the signal (6db drop):

X = ln(Er/Et)/-kf = -ln(0.5)/kf

Since k and f are constants, x is also constant with a typical value (in good concrete) of 60cm (2 feet) and much higher values in water.

The following graph was created by holding one sensor at the bottom, and pulling only the other sensor, hence gradually changing the distance. The data was exported to CSV, and plotted using a spreadsheet. The maximum distance logged was 4.5m (!) and the linear correlation is 0.99. The slope indicates exactly 10db/m (=6db/60cm) - so the energy drops to half every 60cm. The total energy drop is 40db = 2 orders of magnitude.

9. TomographyThe equipment

To perform tomography, you should have two instrumented depth meters, and a suitable "Y" depth cable.

Overview

In CHUM, perform tomography by pulling both transducers together, normally, and when passing a suspected zone, raise and lower each of the transducers in a special way to collect diagonal readings. Once the suspected zone is "covered" from all angles, level the transducers and keep pulling normally up to the top of the pile or the next suspected zone.

See here a general discussion about tomography

Know your left and right!

It is critical to assign the correct depth meter to the correct access tube. Failing to do so will produce mirror images in 2D tomography, and will produce meaningless junk in 3D tomography!

The assignment convention is by color codes. Green=Primary. Red=Secondary

Er - The received energy

Et - The transmitted energy

k - Attenuation factor of the medium

x - Distance between the transmitter and receiver

f - Signal base frequency (Hz)

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Older model "Y" cables are connected directly to one depth meter called "primary" and then branches to the other meter, called "Secondary".

The primary depth encoder is always assigned to the first profile letter and the secondary, to the second letter.

For example:

� When logging profile "34", place the primary encoder on tube "3" and the secondary on tube "4".

� When logging profile "NS", place the primary encoder on tube "N" and the secondary on tube "S".

If you have mistakenly logged the data in the wrong way, you should re-log the profile, or simply rename it to "43" or "SN".

On the tomography plot, the primary channel is always on the left.

How to collect the data?

To collect good data, the following conditions must be satisfied:

1. All the profile area should be "covered" by horizontal readings (The software can extract those readings only to produce a 1D CSLplot)

2. Every pixel in the suspect zone should be covered by at least two forward (//) and two backwards diagonal (\\) readings. The more,the better.

Mathematically, each pulse is a row (Linear equation) in the matrix. To get consistent results, you must get an over-determined matrix. (More pulses than pixels). The way the data is collected in the CHUM system generates a good distribution of information (matrix very-over-determined on suspect zones and under-determined in good pile zones)

In order to get consistent results, the data must be collected in a consistent way, for this, a data collection procedure is defined. The procedure collects the data in "fans". As demonstrated below:

The right transducer is lowered in small step and for each step, a "fan" of samples is performed by the

A schematic way to describe the procedure is by plotting D1 against D2

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In words:

1. Pull both transducers horizontally until above and out of the defective zone (Point A)

2. Keep #1 steady, and lower #2 until the signal is almost lost (You can go over +/- 45deg)

3. Keep #2 steady and lower #1 by a small increment (about 2-4 inch)

4. Keep #1 steady and raise #2 until the signal is almost lost, or both #1 and #2 are above the suspected zone

5. Again, Keep #2 steady and lower #1 by a small increment (about 2-4 inch)

6. go to step 2 until both #1 and #2 are below the defect zone (Point B)

7. Level #1 and #2 to horizontal (+/- 2deg) and continue pulling upwards till the top, or the next suspected zone

And in an animation of the process

http://www.piletest.com/downloads/TomographyDemo.exe

This might look complicated at first, but it is actually simple, and once you practice it, it is very easy to use in the field, and will give you good, repetitive results each time.

Take your time, and practice this several times in a non-stressing environment.

While the data is logged, watch the following indications

� Primary encoder pulled up (└ ) down ( ┌ ) or steady ( ─ )

� Secondary encoder pulled up ( ┘ ) down ( ┐ ) or steady ( ─ )� Average length pulled from bottom (H:nnn.nn)

� Angle between transducers (0° is horizontal)

� FAT and Gain on the oscilloscope window

Once the data points are collected, they can be viewed and reported in all presentation modes. The data can also be presented in the one-dimensional lines plot or waterfall presentation. For this, the software filters-out the diagonal readings and uses only the horizontal ones.

� TIP: When doing tomography, change the vertical spacing in the options logger tab to a smaller value, such as 2-3cm (0.75" – 1.0")

See also: Signal classification options

Types of tomographyCHUM supports the following tomography methods

� Real time (Based on simplified fuzzy-logic)

second transducer (It does not matter which of D1 and D2 is primary or secondary)

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� Fuzzy-logic

� Parametric

� Three Dimensional (3DT)

The data points for all types of tomography are collected in the same way. For 3DT, enough profiles must be collected to cover the pile’s cross volume.

Principle of Fuzzy-Logic (and real time) tomography

In one sentence: "A concrete pixel is painted by the highest category of the rays passing through it."

In detail:

� The profile is broken into pixels

� All the rays passing through a pixel are collected, and assigned a color category according to the logical classification conditions you

specified.

� The classification counts are sorted, and the final color is the Nth order-statistics, where N=100-2*Filter (No filter � N=100 =

Maximum). Using order-statistics instead of just Maximum compensates noisy readings. In real-time tomography, N always=100To speed things up, CHUM is using a variable pixel size. Initially, the whole pile is considered as one pixel. If all rays going through a pixel agree on color (or the pixel is small enough) it is painted, otherwise it is cut to two smaller pixels, and so on.

Limitations of Fuzzy-Logic tomography

� The calculations are done on apparent velocity and attenuation. Those are an average of values along the ray path. The apparent

value is therefore always higher than (or at best equal to) the value inside the poor-quality pixel. As a result, the contrast of fuzzy-logic tomography is lower than matrix-based solutions.

� Because of angle limitations, the plotted areas always show "ghost" shadows

3D tomography

3DT is an optional component of CHUM and is being sold separately.

3DT is the next step in tomography, and its success depends on the success of the 2D tomography phases. Do not try to "force-feed" the 3DT algorithm with poor 2D results hoping that it will somehow turn it into good 3D result.

Before performing 3DT, verify the following:

� FAT pickings have been performed and reviewed.

� All profile names map to the pile schema – those are used to locate the profiles in the X-Y plane

� Profile names are using the encoders conventions (See Know your left and right)

� All tube distances are correct

Open the Pile details page and select [More��] and [3DT]

(Or run the CHUM3DT directly from the start menu)

The 3DT wizard opens

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Follow the wizard to perform the matrix inversion (can take some minutes, or significantly more, depending on the data and computer power)

The calculations results are kept in a file, and in the next time, you can just view the results instead of re-calculating them.

Once the calculations are done, the following screen appears:

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3D Image pane: Moving, tilting and zooming the pile.

You may also use a joy stick, if one is connected to your system.

The 3D image is plotted using the whole pane width. Drag the separator splitter between the panes to enlarge it, or even hide some panes to get more viewing area.

Horizontal slicesFrom the [View] menu, select [Slice plane] in order to show a semi-transparent plane showing the slice level. Drag the pile up or down to control the slice elevation. Where available, the middle mouse button, or clicking on the mouse wheel can be used for the same purpose.

The whole horizontal slice pane can be hidden by selecting [Horizontal slices] from the [View menu]. The [-] icon on the pane can also be used for that.

You may instruct the software to collect all the horizontal slices that have low wave speeds by selecting [Tools]-[Collect...]. the slices are collected into a list, you may remove slices from the list by clicking the small [-] icon on the upper-left corner of each slice. Clicking on the slice moves the pile to that level.

The profile is plotted using the whole pane width. Drag the vertical splitter between the panes to enlarge it.

Action Mouse Other

Rotate the camera around the pile axis Drag Left-Right: -

Move the camera AND the view point up or down Drag Up-Down -

Move the camera up or down, keeping the view (Tilting the pile)Right Drag + Up-DownCtrl + Mouse: Drag Up-Down

-

Zoom in or out Wheel up-down Zoom in/out icons

Show/Hide the vertical slice disk Click on mouse wheel Menu: View - slice plane

Revert to the initial view (If you are "Lost in space") - Toolbar: top icon

View the pile's toe Toolbar: bottom icon

Change threshold speed Click/Drag on the palette -

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Vertical slicesDrag the [A] and [B] positions around the pile to define your profile. [A] will be presented on the left.

The profile is plotted to scale (without X-Y distortion) using the whole pane width. Drag the vertical splitter between the panes to enlarge it.

ReportingReporting is done by a "copy n’ paste" operation, directly into your report document. select one of the [Edit]-[copy]-[...] options to copy the desired image into your clipboard.

Switch to your report document, and press Ctrl+V to paste the graphics. Repeat with all the needed graphics.

Note that when pasting directly into your word processor, the slices graphics are copied using a vector format. Using this format the images size can be enlarged and reduced without losing resolution. the format is also more compact in size. The 3D graphics are created in a simple raster (photo) format.

Generating a 3D movieFrom the [Movie] menu, select [Action] to start recording. Move the 3D image around to show the anomalies from the best view angles, and select [Cut n’ print] to generate the MPEG movie. During the recording, watch the number of frames and the movie file size on the bottom status bar.

� TIP 1: In order to get smaller file size movies and faster response during recording resize the window to a smaller size before starting .

� TIP 2: Movie segments can be easily edited and narrated using a video editing software, such as the free "Windows movie maker" by

Microsoft.

Appendix A - Frequently Asked Questions (FAQ)The questions and answers below are a collection of real questions asked by real customers.

A.1. Category: The Equipment

What type of computer can we use with your equipment, storage etc.

For testing on site, the ideal computer is a Tablet PC, running Windows XP/Vista. We have had excellent experience with tablets, and they are highly recommended.You can use a regular notebook computer on site, as long as it runs Windows XP or higher and has a USB port

Note that the LCD display of normal notebook computers is NOT designed to work outdoors, and its brightness cannot compete with the sunlight.

For office work you can use any Windows computer and printer.

Can your equipment correspond with computer?

and analysis and reporting in the office.

A.2. Category: Test Method

What is the effect of bulging on attenuation?

Bulging has a negligible effect on attenuation, while necking has a marked one.

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What is the unit 'dB' used for calculating the attenuation and what is its dimension?

Decibels are commonly used as a relative measurement of attenuation on a log scale. You can read more in

http://arts.ucsc.edu/EMS/Music/tech_background/TE-06/teces_06.html. The dB is convenient for our purpose, because it enables us assign numerical values to attenuation and thus define anomalies quantitatively.

What are the maximal length and diameter of testing piles?

With the CHUM you can test piles of any diameter to depths of 145m!

Can we test integrity of reinforcement in piles and it length?

No.

Can we test reinforced piles?

1%) has no influence on the results.

I have a question concerning the CHUM module. Currently we are working on a project in which we are trying to locate an existing below ground tunnel. The tunnel is located in the Cooper Marl formation approximately 100 to 120 feet below the ground surface. The Cooper Marl is a relatively homogeneous calcareous sandy, clayey silt typically used as the bearing layer for the Charleston area. It has typical compressive wave velocities of 5400 ft/sec and shear wave velocities of 1400 ft/sec based on SCPTu testing. The tunnel was 8 feet in diameter when constructed and may or not be lined. My question to you is could the CHUM be used to detect the tunnel? Our plan using the CHUM would be to install inclinometer casing approximately 20 to 30 feet apart and use the tomography option to accurately locate the tunnel. So my questions are: Is the concept feasible? In theory, I would think it is just like detecting a defect in a very weak concrete, but theories have a way of staying theories. If so, would modifications to the CHUM hardware and software be required? The first arrival times would be very long (on the order of 5 microseconds). What would be the approximate cost of these modification be and how long would it take to make them? If not possible, could the CHUM receivers be used to detect shear waves? We were also thinking of possibly using shear waves to detect the tunnel.

-quality concrete is 3-4 meters, I am afraid the energy emitted by the CHUM emitter is just too low to reach those distances and still be of value. This may seem a drawback, but since the CHUM is designed to emit many thousands of pulses per day and still be portable enough it is unavoidable. You will have therefore to consider other techniques.

A.3. Category: Testing

In the visible graph while pulling out transducers, what does the width of the graph stand for, also what is meant by necking in and out of the graph & also the projection of slight slashes in the graph pulse, please clarify with examples.

The width of the graph is proportional to the received energy. Small changes in real-time are usually noise. Larger changes might indicate flaws. Post-processing usually reveals more information. Slight slashes - I'm, not sure what you mean. If it is the diagonal lines on the pulse scope - those are merely a graphical way of showing the FAT. If you meant the crisscross on the logging window - this comes to

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show a difference between tested and untested areas. Since the display is practically B&W in direct sunlight - this is a simple way of showing a "third" color.

What does the voltage in Scope Window stand for? Has the FAT any relationship with the voltage, as we have observed a inverse proportionality between FAT & Voltage in site.(i.e as FAT increases Voltage decreases &vice versa) What should be the voltage when we are about to start pulling.

CHUM is using Automatic Gain Control (AGC) - automatically changing the dynamic range of its A/D converter in order to use the range that best fits the sample size. The voltage scale can change in eight levels between 5V, to 10mV. As the pulse amplitude drops -CHUM is using a smaller range, and vise versa. The behavior you saw is natural and expected to have the range change in inverse proportion

to the FAT (See What is "Attenuation"?)

It was observed that during the testing, we are losing 30 to 35cm of pile length, could you please explain.

This is the transceiver length. Testing starts when the BOTTOM of the transducer touches the BOTTOM of the tube, but stops when the TOP of the transducer reaches the TOP of the tube. If the tube is only 31cm long - the transducer can only move 1cm inside it. This is OK and is inherent to this test method.

We could see that in some cases, the Attenuation curve is touching the FAT curve and in some cases the Attenuation curves come first and then the FAT curve and Vice versa also. Has this got any implications?

No! FAT and attenuation have different units. The curves are plotted on the same area in order to save space and nothing more. If I was to pick different axes values, the curves would touch at a different, arbitrary point.

Does pulling velocity have any effect on the test result?

Pulling speed has no effect on the results. The encoder constantly transmits the depth to the instrument, and a pulse is sent in predetermined vertical spacings.

Our CHUM is not showing the exact spacing between the sonic tubes. (for eg. When we measure 0.64m in the site the CHUM is showing 0.88m).we have tried this out in some 10 piles and still the error is existing.

In the leveling screen, the distance is only an estimated (this is why it has the ~ sign next to it) CHUM can only measure time, not distance! The distance is calculated assuming a wave speed of 4400m/s. In your case, the wave speed might be lower - the concrete might be too fresh or of lower grade/quality. Anyway - the distance value is presented in this screen in order to help you level the pulses, not for reporting.

A.4. Category: Interpretation

What are the criteria for FAT & Attenuation to judge pile integrity i.e. during our testing, some FAT will be 184µs and for other pile it will go to 260µs. Also how FAT is related to concrete quality & what is the range of values of FAT &Attenuation for good & bad piles. Please advise with examples.

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FAT stands for First Arrival Time. Since the wave speed in cured concrete is about 4300m/s (+/- 10%), it will take the wave 1ms to pass 4.3m, 500us to pass 2.15m and 250us to pass 1.075m etc. Since profiles are never at the exact same distance, it is expected that the FAT will change. 184us is typical for a profile of 0.8m and 260us corresponds to 1.1m If your FAT is too high for the profile distance, the concrete might not be cured or it is of low quality/grade. The received signal has a measurable energy. The energy drops exponentially as the distance grows. It is expected for the energy to remain roughly constant in a homogeneous concrete. Attenuation is simply the energy in decibels (dB) units, relative to the maximal energy that can be recorded. A change of 6dB means half the energy, 12dB is 1/4 the energy, etc.

(See What is "Attenuation"?)

generally taken that the FAT gives the biggest indication of inclusions or defects, however, I note on your web site that a low relative energy means a "weak" signal. When would I expect to get a weak signal, and could it represent an anomaly even if the FAT's are consistent?

Weaker signal with no change in FAT can be generated when the wave path becomes narrower, for example, in the case of a necking.

As seen in this image, the shortest path between source and receiver is not disturbed; therefore the FAT shows no indication of the defect. However, the total amount of energy reaching the receiver is significantly reduced. This is just one way of explaining this phenomenon. I am not aware of any research done to quantify it or find additional explanations. There is no way to assess the size and severity of the defect (if it is indeed a defect) from this trace, but you quite confidently assess that if the energy dropped significantly (say by 18 db or more in the attenuation curve) you are not crying wolf.

In general the traces are quite smooth (about a vertical line), but every now and then the line is very jagged, although still about a vertical line. Does this sound like a problem?

Concrete is not a homogeneous material and some variations of the FAT and attenuation are to be expected even in the most controlled environment. Unless you can see a significant change in FAT or energy (And I cannot quantify this change) you are safe.

How can we estimate the distorted area of the pile, from FAT & Attenuation?

There is no standard, and you have to apply solid judgment for changes in FAT or attenuation. I recommend that you will send the files to us. We will be glad to assist you with the interpretation until you feel confident enough.

Which is the easiest method of evaluating a pile, like FAT vs. Attenuation or FAT vs. Energy. Explain.

Those are equivalent. Originally CHUM only showed Energy (without units). We introduced Attenuation in a later version, but kept the energy option for backward compatibility with those users who already got used to present and submit energy curves in their reports.

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In our Equipment, for the PRESENTATION of results, we are allowed to choose from FAT, Attenuation, Relative Energy & Apparent Velocity. BUT, when we choose the Apparent Velocity option, We are able to see a green legend for Apparent Velocity in the bottom of the graph & also the velocity written in m/s., BUT there is no representation of it in the graph.

CHUM can only measure arrival time, not signal velocity. In order to plot the velocity curve, you must enter the horizontal spacing between the tubes. Once you enter this value, you will be able to see the velocity curve.

A.5. Category: Reporting

Can we copy or duplicate a pile in the CHUM.

No. But you can do this in Windows - open the project folder, copy the file (right-click - copy. Right click on the folder - paste). Now re-open the project and rename the pile. May I ask why you need this option for?

A.6. Category: Training

Do you conduct the seminars for users?

Training can be arranged at cost.

Appendix B - Checklists Before going out to the site, check that:

You packed:

The instrument

The software is properly installed.A good practice is to look for new CHUM versions at least once a month in Piletest.com user community download area

The instrument’s battery is fully charged.

A set of transducers (emitter and receiver)

Two pulleys, including at least one depth meter.

Depth cable

The relevant project documents

Optionally:

battery charger / lighter charger

A sounder

�� Tip:

Hot weather: Drinking water, a hat.

Cold weather: Warm clothing. Coffee?

Appendix C - Troubleshooting

C.1.1 Symptom: No Signal, or no response from the CHUM

Troubleshooting

1. Connect your set of transceivers and place them in a bucket of water.

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2. Connect the USB to the computer

3. Start CHUM software

4. ?: The green LED on the CHUM panel is OFF

� Possible diagnostics: Low or exhausted battery

� Possible diagnostics: Damaged computer USB port

� Possible diagnostics: Damaged CHUM unit

5. Click the wrench icon

6. Make sure the USB CHUM data source is selected

7. Press [Test]

8. ?: The software brings up an I/O error message

� Possible diagnostics: Low or exhausted battery

� Possible diagnostics: More than one instance of CHUM is running

� Possible diagnostics: An additional CHUM/PET system is connected.

9. ?: A No error message, the scale at the oscilloscope window is low (39mv) and there is no distinctive signal

� Possible diagnostics: Damaged transceiver

10. If you have a transducer emulator, connect it

11. ?: The greed LED on the emulator is flashing

� Possible diagnostics: Damaged transceiver

12. ? : CHUM works well outside, but not when testing a real pile

� Possible diagnostics: no water in the access tubes

� Possible diagnostics: Defective pile/soft bottom

C.1.2. Symptom: Wrong or inconsistent depth readings

Troubleshooting

1. Connect the depth encoder(s) and the depth cable 2. Connect the USB to the computer 3. Start CHUM software 4. Click the wrench icon

5. Make sure the USB CHUM data source is selected 6. Press [Test]7. Use a pencil to mark a line on the depth wheel 8. Rotate the depth encoder a whole turn clockwise, and than counter clockwise to about the same point. Watch the "counters" reading 9. ? The counter reading did not change at all

� Possible diagnostics: Damaged depth cable

� Possible diagnostics: Damaged depth encoder

� Possible diagnostics: Damaged CHUM unit

10. ?: You are using two encoders and each one moves in a different direction

� Possible diagnostics: One of the encoder bases is rotated 180degrees. Disassemble and fix it.

11. ?: You using two encoders. They both change the same way, but at different speed (Different counts/revolution)

� Possible diagnostics: Two encoder models are used. Don’t mix and match encoders from different models, contact Piletest.comfor a workaround.

12. ?: The counter reading changed to +/- 1 and 0, but nothing beyond that. or

13. ?: The counter reading changed just on one way


� Possible diagnostics: Damaged depth encoder

14. ?: The counter reading changed significantly one way and than back to (nearly) zero?

15. Perform depth calibration, twice to verify repeatability 16. ?: The results of each calibration are very different (More than 0.1% off)

� Possible diagnostics: The wheel might have collected too much dirt/ice and does not rotate freely, so the cable slips over it


C.2. Possible diagnostics:

C.2.1. Possible diagnostics: Low or exhausted batteryConnect the CAR charger to the CHUM unit, and use a voltmeter to measure the voltage directly.

See CHUM internal battery and battery charger

C.2.2. Possible diagnostics: Damaged computer USB port

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� Connect the CHUM unit to another computer with CHUM installed to verify the the problem is really the USB port

� Try to connect other peripherals, such as a mouse or a disk-on-a-key to the port, and verify that it works well

C.2.3. Possible diagnostics: Damaged CHUM unitIf you have verified that the unit is indeed defective, Contact [email protected]

C.2.4. Possible diagnostics: More than one instance of CHUM is runningOpen task manager – (on XP, use Ctrl-Alt-Delete) and switch to the processes tab. Check [●] show processes from all users, sort by process name and look for CHUM.EXE – only one instance is allowed. Kill other instances

C.2.5. Possible diagnostics: An additional CHUM/PET system is connected. Simply disconnect other CHUM/Pet units

C.2.6. Possible diagnostics: Damaged transceiver� Try to swap the transceivers (Tx � Rx), if this solved the problems, one or more of the transceivers is not functioning as dual-

purpose anymore.

� If you have a spare transceiver, try all 6 combinations to pinpoint the faulty function

� Examine the transceivers cable manually for physical damage

C.2.7. Possible diagnostics: Damaged depth cable� Visually inspect the cable for physical damage

� Use an Ohmmeter to test the cable connectivity end-to-end

C.2.8. Possible diagnostics: Damaged depth encoder� Visually inspect the encoder for physical damage, high friction or water penetration

� Cross-check with other encoders, if available

Appendix D - Anomaly? Flaw? Defect?

When discussing pile integrity, it is important to distinguish between three terms that are often confused:

� An anomaly is any irregular feature in the NDT graphic results. An anomaly may be due to the testing instrument (such as noise), to

the means used (access tube debonding in a cross-hole test), to the surrounding soil (abrupt changes of soil friction in the sonic test) or to the pile proper. It is the responsibility of the testing laboratory to gather and analyze all relevant data and try to resolve every anomaly before it is declared a flaw.

� A flaw is any deviation from the planned shape and/or material of the pile.

� A defect is a flaw that, because of either size or location, may detract from the pile’s capacity or durability. The geotechnical engineer

and the structural engineer are jointly responsible to decide which flaw comprises a defect.

Appendix E - Theoretical backgroundE.1. Ultrasonic Testing - Basic PrinciplesThe sonic ("low strain") method belongs to the external test-methods, as it accesses only the top of the pile. Ultrasonic logging, on the other hand, is intrusive and necessitates the prior installation of access tubes (Usually two or more) in the pile. Before the test they have to be filled with water (to obtain good coupling) and two transducers are lowered inside two of the tubes. One of these transducers is an emitter and the other a receiver of ultrasonic pulses. Having been lowered to the bottom, the transducers are pulled simultaneously upwards to produce an ultrasonic logging profile. The emitter produces a continuous series of waves in all directions. These waves do eventually reach the receiver. The testing instrument then plots the travel time between the tubes versus the depth. As long as this time is fairly constant, it shows that there is no change in concrete quality. A sudden increase of the travel time at any depth indicates a defect at this depth. The cross hole method has been described in a number of recognized standards (AFNOR 1993, ASTM 2002 ). As we shall see later, the cross-hole method may be further refined to produce high-quality results.

A variation of ultrasonic logging is the single-hole method (Amir 2002): In this method both emitter and receiver are lowered, with a fixed pre-determined vertical spacing, in the same tube (or hole). In this case the waves do not travel across, but rather along, the pile axis.

While the access tubes introduce an extra expense item, the cross-hole technique compensates for this by allowing the testing equipment to approach potential defects. An additional advantage of this test is the enhanced resolution: While the sonic test uses a wavelength of at least two meters, the cross-hole method utilizes ultrasonic frequencies, with typical wave lengths of 50 to 100 mm. Since resolution is strongly dependent on the wave length, the cross-hole method enables us to locate even minute defects.

Because of these short wave lengths, the one-dimensional theory, on which we based the sonic method, is no more applicable. Thus, we have to look into the theory describing the behavior of waves in space.

E.2. Three-dimensional wave propagationIn prismatic rods, we meet only one type of wave - the one-dimensional longitudinal wave which can be either compressive or tensile.

Body waves moving in a three-dimensional elastic space, however, may be of two distinct types: Dilatational (P-Waves) and distortional (S-Waves).

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When the displacements associated with the wave occur on the axis of wave propagation (as in the rod), the waves are called longitudinal or P-Waves. The particles in this case may move either in the same direction (compressive wave) or in the opposite direction (tensile wave). P-Waves are accompanied by volume expansion or decrease.

When the wave causes particles to move perpendicular to its direction of motion, the waves are known as S-Waves or shear waves. The character of S-Waves is further determined by the direction of displacement: When particle displacements are horizontal, the waves are called SH-Waves. SV-Waves, on the other hand, are characterized by vertical motion. A general S-Wave may be decomposed into its SV and SH components.

As mentioned before, waves radiate from the point of application of any dynamic load. As the distance from this point increases, the waves may be assumed to travel as a plane front. All material particles then move in this plane (S-Waves) or perpendicular to it (P-Waves). This

assumption leads to substantial simplification in the mathematical treatment: If we denote the particle displacement by �, then the propagation of plane waves is governed by the following differential equation:

Equation 1

in which for S- (or distortional) Waves and for P- (or dilatational) Waves. c, as usual, is the

wave propagation velocity. For Poisson’s ratio �=0.25, the velocity ratio cP/cS is equal to �3, which means that P-Waves propagate much

faster than S-Waves. For good-quality concrete, cS=2,580 m/sec and cP = 4,470 m/sec. In comparison, c for a rod of the same material is

equal to 4,080 m/sec.

To visualize the behavior of plane wave, we often prefer to trace a single normal to the wave front, and follow its’ path. As an analogy to optics, the trajectory of such a normal is termed a ray path.

E.3. AttenuationWhen a wave front moves away from the emitter, it becomes larger with distance. If we assume that no energy is lost during the process, the energy per unit area of the front (or per ray) declines with distance. The rate of decrease depends on the shape of the front. If the front is spherical, the wave energy per unit area will change as the inverse of the square of the distance from the source:

Equation 2

Where:

E1 and E2 denote the respective wave energies at points 1 and 2, respectively, while r1 and r2 are the respective distances from the source

of points 1 and 2. Since the energy E is proportional to the square of the amplitude A, Equation 25 can be re-written as:

Equation 3

Equation 3 describes what we define as geometric attenuation, which occurs in all types of media and is the only source of energy loss in perfectly elastic materials. In real materials, which also exhibit viscous and frictional behavior, part of the mechanical energy of the waves is constantly converted into heat. This phenomenon, defined as material loss or intrinsic attenuation, is represented by the following equation (Santamarina et al. 2002):

Equation 4

in which k is a medium-dependent constant and f is the wave frequency. Equation 4 shows clearly that material attenuation causes the wave amplitude to decrease with increasing distance from the source, at a rate that is dependent on the frequency. Higher frequency waves attenuate much faster than those with lower frequencies and therefore have a smaller range.

Since wave amplitudes may vary over a few orders of magnitude, it is convenient to express amplitude ratios on the decibel scale, defined as dB = 20∙log(A2/A1). Since 20∙log(0.5) ~ 6, every 6 dB represent an amplitude ratio of 2.

Figure 1 is an example obtained by passing ultrasonic waves in a concrete pile while varying the distance between the emitter and the receiver. The exponential character of the attenuation is immediately apparent.

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Figure 1: Attenuation of Ultrasonic Waves in Concrete

E.4. Waves in an elastic half-spaceWhen a dynamic load is applied at the free surface of a boundary, both P- and S- waves radiate from the point of application into the body. In addition, this load will produce surface waves that are not dissimilar to the ripples created by throwing a stone into calm water. These surface waves, named after Lord Rayleigh, include longitudinal and transverse components. They are confined to a thin layer close to the surface and propagate at a velocity that is slightly smaller than cS.

Inside an infinite uniform body, plane body waves will propagate in straight lines. In a half-space, some waves will eventually hit the boundary x = 0 and will be reflected back into the body having undergone several changes:

When the waves hit the boundary at a right angle, P-Waves will change sign: Compressive waves are reflected as tensile, and vice versa. This follows directly from the requirement that the boundary be stress-free.

When a wave meets the boundary at an angle q1<900, it undergoes mode conversion and is reflected back as two distinct waves: A P-wave is

reflected at the angle of incidence q1, and an SV-wave is reflected at a different angle q2< q1 (Fig. 1 - Kolsky p. 24).

When the incident wave is of SV type, it will create two distinct reflected waves: An SV-wave will be reflected at the angle of incidence q2, and

a P-wave at a larger angle q1.

Figure 2: Reflection of P-Waves from the boundary x = 0

The amplitudes of both reflected waves depend on the amplitude of the incident wave, the angle of incidence and Poisson’s ratio (Kolsky pp. 27-28).

Waves in Non-homogeneous Media

Up to this point we have dealt with homogenous media. For our purposes, a medium is defined as non-homogenous when it fulfils the following two conditions:

1. The medium includes zones with different characteristic impedance:: ��.c)

2. The typical size of these inclusions d is much larger than the wavelength �.

In such media, whenever a wave hits an inclusion, its propagation pattern will change at the interface. Here we shall distinguish between two cases:

Normal incidence

When a wave with an amplitude Ai travels from a region with the impedance Z to a region with another impedance Z’ through a normal

interface, it will be partly reflected back with an amplitude Ar while another part will pass through the interface with an amplitude At.

Therefore, when a wave meets a weaker region (Z’<Z) it will change sign: A compressive wave will be reflected as a tensile wave, and vice versa. If, on the other hand, Z’>Z the reflected wave will preserve the sign of the incident wave.

This ratio At/Ai is always positive, which means that the transmitted part of the wave will preserve the sign of the incident wave.

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Oblique Incidence

When a wave meets the interface at an angle �1 to the normal, it will create four new waves: Two of them reflected and two - refracted (Figure

3).

Figure 3: Reflection and refraction of P- and SV-waves

E.5. Media with inclusionsA generalization of the case, which we discussed above, is that of a given medium with an inclusion of an arbitrary shape having different properties. This situation, by the way, is of most importance to those who are in the business of locating defects in cast- in-situ concrete piles. From our previous discussion we may now realize that in a typical case, an incident wave will create four distinct waves when hitting the inclusion. Of these, two will enter the inclusion at different angles, and each of those may create four more waves upon leaving the inclusion. Thus, for each ray path hitting a typical inclusion there will be two waves reflected back from its boundary and a number of waves leaving at various locations and angles. Clearly, a mathematical treatment of the general case (An inclusion with an arbitrary form) is rather hopeless. Idealized cases, such as a plane wave in an infinite medium with a spherical or cylindrical inclusion, may be treated by analytical methods using infinite series (Graff p. 394 ff.).

A typical case of a plane P-wave hitting a cylindrical inclusion is demonstrated (For a single ray path) in Figure 4. In this example, a single wave creates three pairs of waves exiting the cylinder. We note immediately that none of these follows the original trajectory! The amplitudes of each wave and its sign (either compressive or tensile) are shown as a fraction of the amplitude of the incident wave.

Figure 4: A P-wave hitting a cylindrical inclusion

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Documents

Mk @MSITStore C -Program Files (x86)-Piletest.com-CHUM.chm