Dynatest 3031 lwd light Weight Deflectometer



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10Plot

10.1Options, Rawdata, Backcalculation Design, Copy, Graph Sectioning


Selecting Plot from the Main menu gives access to a range of graphical presentations, statistics a.o. In unlicensed mode the facility is only available for the Demo database. For a number of the graphics Options can be activated from the Plot menu for selecting various settings for the current graph. Below the graph window a table with the relevant data is available, and for graphs with location along the x-axis, sectioning feature and statistics in table form is available.
The contents of the tables can be copied and pasted to other applications, like Excel.

Click the button to copy the table to the clipboard. The button is located close to the table that will be copied. Follow the links above to see more detailed information for the various graphs and functionalities.


10.2Plot - Options


For most graphs in the PLOT facility, it is possible to select Options from the menu to enter various settings affecting the graphic presentation.
The possibilities you have in Options depends on the current graph displayed. In the example below you see the options for deflection graphs.

10.2.1Normalize to


Since the drops for a test points often are made with various load levels, it is necessary to normalize the deflections to a specific load level for comparison purposes. The load level is entered as the stress level under the plate. From the Stress column in the deflection table, you can get an idea of the magnitude of stresses obtained during testing.

10.2.2Select sensor


If tests have been carried out with more than 1 geophone sensor, it is possible to select which sensor output that should be used in the graphics.

10.2.3Show drops


You can select to display results from all drops from a test point, or you can limit it according to the other choices. Often in the analysis you restrict the drops to be used according to some criteria set up in File Settings. If you select the option As used in File Settings, the graph will reflect the same restrictions. You can click the button File Settings to view the setup, and also to change the settings. If you do changes and save these, then be careful, because the new settings will be used also in following analysis. In File Settings you can also select to compensate the centre deflection with the Offset, which will influence both the deflection graphs, and the surface deflection moduli graphs based on centre deflections.
You can also select to view only drops, where the Offset percentage is higher than a specific value. The Offset percentage is 100 * offset/centre deflection. Do not use this in combination with centre deflection compensation for offset.

10.2.4Mean and Deviation


This option can be used with the graphs including all locations displaying deflections or surface deflection moduli. This will for each location calculate mean value and standard deviation, and show these values on the graph. For the deflection graph it should be used in combination with normalizing the deflections.

10.3Plots - Rawdata


Deflections Surface Deflection Moduli Time History Drop Statistics
Under Plot>Rawdata a collection of various graphs are available to present the measured data. They can be very useful to get an overview of the contents of the file, and further to give a first expression of the quality of the data, and the condition of the tested structures. Features for deleting obviously useless drops are available. There are possibilities to do selective viewing, to normalize deflections and to do both general views as well as viewing details for selected drops.
Follow the links above to get more detailed descriptions of the various graphs.

10.3.1Plots - Deflections


Select Plot >Rawdata >Deflections >All Points to view and compare all measured deflections in the current file.


In the example you see the locations (7 test points) along the x-axis, and for each location a number of deflection readings, a green dot for each drop. There is a lot of scatter in the deflections due to that different load levels have been applied. If you would like to see the deflections normalized to a specific load, you can select Options from the Plot menu:

In the example it has been chosen to view deflections normalized to 100 kPa. Click OK to refresh the graph:


And you will now have a better possibility to compare the deflections.
Notice at the location 1122-6 there is a deflection much higher than the other deflections for that location. This could be considered as an outlier. If you the graph placing the mouse at location 1122-6, you will have another graph showing the deflections only for this location, with increasing drop No. along the x-axis: From this graph you see that the outlier is for drop No. 7. You may want to remove this drop from the file to avoid that it will disturb later analysis. If you anywhere on this graph you will be taken back to the graphs with all locations included, from where you can delete the drop. You can also scroll through the locations by using the arrows in the upper left corner of the graph window.

If you want to delete a drop from a location you have to be at the graph displaying all locations. To delete a drop, hold down the key while clicking on the appropriate green dot. The drop will immediately be removed from the file, and the graph will refresh. It is possible that the scaling of the graph will change. You can also delete a drop by pressing and left click the appropriate line in the data table below the graph.
When making decisions about which drops that should be removed, you have to consider that variations in the normalized deflections may often be due to seating while testing on the same location. If you look at the deflections for point 1122-2:


you will see smoothly decreasing deflections vs. drop No. There is no reason to start deleting the first points, as they indicate the amount of compaction during testing. In these cases it will be better to keep all drops, and following when doing the analysis, only include the last drops. This can be defined from File Settings in the Analysis window.

10.3.2Plots - Surface Deflection Moduli


Select Plot >Rawdata >Surface Deflection Moduli >All Points to view and compare all measured drops in the current file.
The term "Surface Deflection Moduli" is used rather than just "Surface Moduli" to underline that it is the surface moduli calculated solely on the measured deflection on top of the pavement surface.

In the example you see the locations (7 test points) along the x-axis, and for each location a red dot for each drop indicating the calculated surface deflection modulus.


Notice at the location 1122-6 there is a surface deflection modulus much higher than the other values for that location. This could be considered as an outlier. If you the graph placing the mouse at location 1122-6, you will have another graph showing the surface deflection moduli only for this location, with increasing drop No. along the x-axis: From this graph you see that the outlier is for drop No. 1. You may want to remove this drop from the file to avoid that it will disturb later analysis. If you anywhere on this graph you will be taken back to the graphs with all locations included, from where you can delete the drop. You can also scroll through the locations by using the arrows in the upper left corner of the graph window.

If you want to delete a drop from a location you have to be at the graph displaying all locations. To delete a drop, hold down the key while clicking on the appropriate green dot. The drop will immediately be removed from the file, and the graph will refresh. It is possible that the scaling of the graph will change. You can also delete a drop by pressing and left click the appropriate line in the data table below the graph.

10.3.3Plots - Time History


Select Plot >Rawdata >Deflection details >Deflection vs Time to view the time history for a single drop.


The graph displays the load and the deflection as a function of time during the pulse. In the upper left corner navigation buttons are available for shifting between locations and drops within a location.
The load curve is rescaled to match the deflection curve for better viewing. The scale factor is seen at the bottom text.
In the example above the curves are close to ideal, but very often you will see curves deviating in different ways. The most usual deviation is due to that the deflection sensor does not reset to the start level as shown in this example:

The difference between start and end level for the deflection curve is called the Offset .The offset is normally due to either compaction of the material or a small transversal movement of the deflection sensor during the load impact. The offset values for all drops for a location can be seen by selecting
Plot >Rawdata >Deflection details >Offset vs Drop.

In File Settings it is possible to correct the deflections for offset, by checking Use centre deflection – offset. This will affect the display of graphs for deflections and surface deflection moduli, as well as the analysis. It is advisable trying to run the analysis both with and without this correction to view, what will give the most reliable and useful results.


10.3.4Hysteresis


By clicking the Hysteresis button below the graph window it is possible to view a graph displaying the Load vs. Deflection graph for the current drop:

The graph indicates the level of energy transmitted to the pavement during load impact. The bigger area of the graph the more energy is absorbed in the pavement, with expected higher damage effect. In the lower right corner the energy is calculated as the area of the graph.
By selecting Plot >Rawdata >Deflection details >Energy Loss vs Drop the values can be viewed for all drops for each location:

The red curve is the values calculated from the measured deflection curve, while the green line is based on normalized deflections at a specific load level.

10.3.5Plots - Drop Statistics


Click Plot >Rawdata >Drop Statistics to access a couple of graph types giving an overview of the number of locations and drops in the file, and the used load levels.

10.4Plots - Backcalculation


Selecting Plot >Backcalculation three graph types are available to see the results of the analysis of the layer properties:


  • Elastic Moduli

  • Non-linearity

  • Compare deflections

  • RMS

This menu option will be disabled if no results have been saved for the file.


10.4.1Elastic Moduli


This will give a graph for all test points with a curve for each layer indicating the calculated elastic moduli:

In the example the graph shows results from a two layer analysis, where the red line is for the subgrade and the blue line is for the sand layer.

10.4.2Non-linearity


This graph shows the non-linear properties of the subgrade in terms of the C and n values:

A high negative value for n indicates high non-linearity.

10.4.3Compare deflections


This graph shows the measured and calculated deflections for the drops belonging to one location, and where deflections have been calculated:

The buttons in the upper left corner are used to scroll through the locations. This example shows the comparisons for a file, where 3 geophones have been used.
Select Options to control how many geophones that should be included in the graph.

10.4.4RMS


This graph shows the Root Mean Square values of the back-calculation. This means for each location the total RMS for the drops used in the analysis. It can be based on the absolute difference between measured and calculated deflection, or it can be the relative difference in percentage as shown in the example below. The choice can be set from Options


10.5Plots - Design


From Plot >Design the results of design calculations are shown.

In the example the required overlay with a standard material is given for each location in the file. The settings for the standard material can be viewed from File Settings. The design calculation is based on specifications to the final surface deflection modulus, which is a part of the input in the Analysis window. From the statistics at the lower right corner, it is seen that mean value + standard deviation gives approximately 260 mm.

10.6Plots - Copy Graph


Selecting Plot >Copy Graph gives possibility to send the graphics to the default printer or to copying it to the clipboard and following paste it to other applications like Excel o or Word.

To copy the data tables use the button located at the tables.


10.7Plots - Sectioning


For graph types with location along the x-axis it is possible to use the sectioning feature. When an appropriate graph is displayed select >Sectioning View.
This gives possibility to insert section dividers at points for the purpose of defining uniform subsections.
To the left in the graph window a marker with a yellow text box at the top is displayed. This can be dragged and dropped at the proper location by positioning the mouse pointer in the yellow square. During dragging the locations changes in the text box, indicating the location of the current point that will be the first point in the section to the right of the marker position. When releasing the mouse button the current section is divided into two new sections. Repeat the procedure if more subdivisions are required. In the example below 3 subsections have been defined.

The statistics window at the lower right corner has changed to reflect the new subsections. New tabs are created with statistical information of the new subsections.
For temporarily hiding the markers click Sectioning >Hide and displaying them again with Sectioning >View.
For saving the information permanently you must select Sectioning >Save.

Select Sectioning >Reset to remove the section divider settings.


11Demo File


A demo database to be used for demonstration and for practicing is located in the LWDmod program folder with the name Demo.mdb. This can be used with the program also in unlicensed mode and when the program is running in DEMO mode with all program functionalities available.
The database has the Demo data in both SI units and US units under the file names Sand (SI) and Sand (US).
When running the DEMO database the raw data cannot be changed or deleted.
The demo data contains tests from 5 test points with numerous drops in each test point with variations in load size.
The structure is about 100 mm (4 in.) of sand/gravel upon the subgrade.
For the first two test points drops have been made on various plate sizes
Open the database and the data file as described in Create, Open and Import
Use the features in Edit Data and Plots - Rawdata to get an overview of the test data.
Select Analysis and select the first test point to enter the structure and do analysis. An example of input data to the analysis is shown below:

As you see not all drops are included in the analysis, because from File Settings it has been marked that only last drop in each sequence should be used. For details about selecting drops see File Settings.
You can now click Calculate Point to get the results for this point only. Using Calculate Point will not save any results. Click Save to save results for a single point, or click Calculate Project to calculate and save results for all points in the file. When calculation of E-values has been done, you can continue to do Surface Modulus Design. For more details about analysis see Analysis.
At any time you can go to Plot from the Main menu to view results in both tabular and graphics form. See Plot for details about features.


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