Civil Analysis - Ground Grading

Civil, Ground, Grade, Grading, Cut, Fill, Earthwork, Proposed, Surface, Spot, Terrain, Data, Export, Analysis

Vito Bindokas avatar
Written by Vito Bindokas
Updated over a week ago

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Ground grading

Start by opening the Ground Grading section of the Civil Analysis menu. Then select the PV area by clicking on Select grading area and choosing the PV area polyline and finalizing by pressing the Space or Enter keys on the keyboard.

PVcase makes a copy of the existing topography in our PV area and any changes will be done using the copy rather than the original. The copy can be found in the PVcase Proposed Grade layer.

This ensures no unwanted changes are done to the original topography and we may later swap between the original and proposed grade to compare the terrain.

Single-axis trackers

Table slope

When performing table slope correction for Single-Axis Trackers, their slope correction is performed in the North-South direction. The following example will illustrate the slope adjustment for a Single-Axis Tracker system.

Having established the frames that are outside the supported slope range, we may set new slope limits that will be enforced with ground grading. To accommodate this, the software will take the offending frames & bring them to the closest acceptable value in the slope range.

For our example, we will take the range values from our Slope analysis and input them into the Grading Slope fields - 6 percent North slope and 12 percent South slope.

We may choose if we want to manually select the frames for which we want to perform these corrections or let the software work with the whole area and modify all the affected frames it finds. Frames that are already within the tolerances will not be affected.

In this case, we will select the PV area boundary line and click on Set Slope. This normally takes a few moments to perform the corrections.

After the modifications are done, the frames that were previously marked with a color indicating that they were out of specification, have now turned blue, meaning that their values were brought to 6 percent or 12 percent, depending on the slope direction. We can move around our design and as we can see, the values are all within the allowed range and in accordance with our specifications.

It is crucial to note that this only addresses the frame slope angle - it has not altered the terrain and frames may be elevated beyond the piling range or even colliding with the existing terrain.

Grading action

Ground grading is directly controlled by the pole length. PVcase will determine how much groundwork would be required to accommodate the newly-established frame slopes within the given pole length range.

Before proceeding to the grading process, one must define the pole length range. These values will be copied over from the Collision analysis Piling range data. In Ground grading, we can see our test values - the lower limit is 1.4 meters, and the upper limit - is 1.7 meters.

In the next step, you can define if and in which case grading is performed not only under, but also between the frames.

If you would like grading between frames, check the checkbox and enter the pitch, up to which space between frames should be graded.

In the following case, grading between frames will be performed (purple hatch), because the pitch is less than the set 7 m:



If the box is unchecked, or the set value is lower than the pitch, no grading between the frames will be performed:


To start this calculation, click on the Grade button. Again, you may select if you want to work with some specific frames or with the entire PV area that was affected. For this example, we will again opt to work with the entire PV area. Frames that are already adhering to the allowed ranges will be unaffected. To initialize the process, press Space or Enter on the keyboard. The process should take a couple of moments.

Once the grading is complete, all the frames that were previously out of specification no longer have a color indication - the terrain has been corrected so that the frames have acceptable pole lengths and are therefore no longer marked by the Collision analysis.

In the Ground grading tab, one is able to switch between the original and proposed ground grade. You may zoom in and check how the pole length values change when toggling between the original and proposed surface. If you click on the Existing grade, the software will switch to illustrate how the piling would be with the original topography. If you toggle to the Proposed grade, it will update the piling to the newly-proposed piling.

Another way to illustrate how the changes affected the piling and terrain would be to perform a front-section view.

Firstly, you may generate the piling by clicking on the Show piling button and selecting the PV area boundary line and pressing Space or Enter on the keyboard.

Then we click on the drop-down menu adjacent to the Cross-section button and select the Front view. You would then prompted to select the PV area boundary line, press Space or Enter on the keyboard to confirm, and then draw the Front-view line, ideally through the middle of the frame, including the piling. You can then place the drawing off to the side by left-clicking on the target location.

To see how the proposed and original topography compares, you may zoom into a front-view cut and see a black line indicating original topography and yellow indicating proposed terrain.

You may have a look at the Area grade section, where it is specified how much terrain had to be cut, filled and what is the net sum of the material being filled and removed.

You may also reset any proposed grading actions by right-clicking on the net result and left-clicking on Reset.

Optimizing the grading

With the initial grading performed and examined, you may also try to reduce the amount of ground moving that is necessary to achieve the desired results.

Before starting, it is highly advised to take screenshots or export the bill of materials. This is to retain the conditions with which we got the initial ground grading results. To do so, go to Layout information, switch to the Bill of Materials tab and click on Select PV area. You would then be prompted to select the PV area polyline; Then finalize by pressing Space or Enter on the keyboard.

You are now able to click on Export to Excel - you will be prompted to specify the target file location and the name of the spreadsheet. You will also be presented with the option to open it immediately or at a later time. For our example, we will click Yes and here we are able to see our grading results and any other data that is relevant to our project.

Secondly, we must reset all the grading actions from our initial grading. We do so by right-clicking on the Net results and clicking on Reset.

For our second iteration, we will focus on the pole length with the current frame reveal of 1.4 meters. If we were to go to the Collision analysis section and click on Indicate, we can see that the majority of our frames are above the threshold, meaning that we can decrease our piling length.

We can do so by going to Frame & Park settings, then clicking on the Park settings tab and decreasing our piling length by 0.1 meters - from 1.4 meters to 1.3 meters and click on OK to finalize. We are now able to select the PV area boundary line and click on Adapt to positions. All the frames in the area will now be lowered by 10 centimeters.

We can perform ground grading again, leaving the same piling length range as before. Once we are done with the grading, we can reference the previously exported bill of materials or screenshots and compare the data.

We now have both iterations of the Bill of Materials and we can compare our results side-by-side. As we can see, our second iteration now requires less groundwork to be done, thus optimizing the results.

You may repeat this process as many times as necessary to get the most effective solution.

Fixed-tilt system

Table slope

Table slope correction for fixed-tilt systems is done in the East-West direction, while Single-Axis Trackers have their slope correction done in the North-South direction. The following example will illustrate the slope adjustment for a Fixed-tilt system.

Having established the frames that are outside the supported slope range, we may set new slope limits that will be enforced with ground grading.

To accommodate this, the software will take the offending frames and will bring them to the closest acceptable value in the slope range.

For our example, we will take the slope value from our Slope analysis and enter it into the Grading Slope limit field - 5 percent. We may choose if we want to manually select the frames for which we want to perform these corrections or let the software work with the whole area and modify all the affected frames it finds. Frames that are already within the tolerances will not be affected.

In this case, we will select the PV area boundary line and click on Set Slope. This normally takes a few moments to perform the corrections.

After the modifications are done, the frames that were previously marked with a color indicating that they were out of specification, have now turned blue, meaning that their values were brought to 5 percent. If we were to look at the previously-shown slope values on the frames, we can see that none of them are indicated as exceeding the slope allowance range values. We can click on Show details and move around our design. As we can see, the values are all within the allowed range and in accordance with our specifications.

It is crucial to note that this only addresses the frame slope angle - it has not altered the terrain and frames may be elevated beyond the piling range or even colliding with the existing terrain.

Grading action

Ground grading is directly controlled by the pole length. PVcase will determine how much groundwork would be required to accommodate the newly-established frame slopes within the given pole length range.

We will continue with the example from earlier. Before proceeding to the grading process, we must define our pole length range.

These values may be derived using the frame clearance values we used in the collision analysis - 0.5 meters as the lower threshold and 0.7 meters as the upper threshold value for the frame clearance. We will re-open the Frame & Park settings window and open the Park settings tab.

In the Height settings section, we set the Lowest point value as 0.5 meters. We can see that in the drawing on the right-hand side of the window, we have the first and second pole lengths for the 0.5 meter clearance threshold - 0.946 meters and 1.907 meters respectively.

Now, we will enter the upper threshold value - 0.7 meters. As we can see, with this value, the pole lengths are calculated to be 1.146 and 2.107 meters respectively.

We may enter these values in the Grading actions section, in the appropriate fields - the top row is used for the minimum and maximum values for the first pole - between 0.946 meters and 1.146 meters. Meanwhile, the second row is used for the minimum and maximum values for the second pole - between 1.907 meters and 2.107 meters.

In the next step, you can define if and in which case grading is performed not only under, but also between the frames.


If you would like grading between frames, check the checkbox and enter the pitch, up to which space between frames should be graded. In the example, grading will only be performed (red hatch) between frames where the pitch is lower than the set 9.9 m:

To start this calculation, we click on the Grade button. Again, we may select if we want to work with some specific frames or with the entire PV area that was affected. For this example, we will again opt to work with the entire PV area. Frames that are already adhering to the allowed ranges will be unaffected. To initialize the process, we press the Space or Enter keys on the keyboard. The process should take a couple of moments.

As we can see, once the grading is completed, none of the frames are marked as affected by the Collision analysis.

To inspect how the piling was affected by the grading. We go to the Collision analysis section and click on Show details. Now, if we zoom in, we can see that the poles are all within the range we specified.

We can go to the Ground grading tab and toggle between the original topography and the proposed one. Let us change to the Existing topography, which generally does not take long.

We are now presented with the piling lengths that would have been given prior to the grading. If we toggle back to the Proposed grade, we will see that the pilings will be adjusted back to the values that are within our specified range.

Another way to illustrate how the changes affected the piling and terrain would be to perform a front-section view.

Firstly, we will generate the piling by clicking on Show piling and selecting the PV area boundary line, and pressing Space or Enter on the keyboard.

Then we click on the drop-down menu adjacent to the Cross-section button and select the Front view. We are then prompted to select the PV area boundary line. We press Space or Enter on the keyboard to confirm, and then we draw the Front-view line as such. We then place the drawing off to the side by clicking on our target location. Please note that the front-view will update automatically.

To see how the proposed and original topography compares, we may zoom into a front-view cut and see a black line indicating original topography and yellow indicating proposed terrain.

We can have a look at the Area grade section, where it is specified how much terrain had to be cut, filled and what is the net sum of the material being filled and removed.

You may also reset any proposed grading actions by right-clicking on the net result and left-clicking on Reset.

Optimizing the grading

With the initial grading performed and examined, you may also try to reduce the amount of ground moving that is necessary to achieve the desired results.

Before starting, it is highly advised to take screenshots or export the bill of materials. This is to retain the conditions with which we got the initial ground grading results. To do so, we go to Layout information, switch to the Bill of Materials tab and click on Select PV area. We are then prompted to select the PV area polyline, having done so we then finalize by pressing Space or Enter on the keyboard.

We are now able to click on Export to Excel - we are then prompted to specify the target file location and the name of our spreadsheet. We are also presented with the option to open it immediately or we can do so at a later time. For our example, we will click Yes and here we are able to see our grading results and any other data that is relevant to our project.

Secondly, we must reset all the grading actions from our initial grading. We do so by right-clicking on the Net results and clicking on Reset.

For our second iteration, we will focus on the current minimum clearance of 0.5 meters. If we were to go to the Collision analysis section and click on Indicate, we can see that the majority of our frames are below the threshold, meaning that we can increase our clearance.

We can do so by going to Frame & Park settings, then clicking on the Park settings tab and increasing our minimum frame clearance height by 0.1 meters - from 0.5 meters to 0.6 meters and clicking on OK to finalize. We are now able to select the PV area boundary line and click on Adapt to positions. All the frames in the area will now be elevated by 10 centimeters.

We can perform ground grading again, leaving the same piling length range as before. We will repeat the steps by clicking on the Grade button and selecting the PV area boundary line and finalizing by pressing space or enter on the keyboard.

Once we are done with the grading, we open the previously generated Bill of materials spreadsheet file and compare the results.

As we can see, our second iteration now requires less groundwork to be done, thus optimizing the results. You may repeat this process as many times as necessary to get the most effective solution.

Surface comparison

As a final step, we can easily compare the existing and proposed grade surfaces using the heatmap provided by the Surface comparison tool. To do so, We have two options on how to illustrate the grading intensity on the project area: either a heatmap, which colors affected segments of the terrain with a corresponding color, or spot levels, which places text denoting the elevation difference in a specific spot on the drawing.

Start by defining the values in the Surface comparison table.

  • Start value - this is the smallest value that will be represented in the heatmap;

  • Table range count - this defines the granularity of the heatmap (number of steps in either direction);

  • Step size - this is the increment in which the values progress.

We start by defining our start value - in our case, we will leave it at 0.05 meters. It is generally best practice to have a table range value of at least 5 - this is to enable us to have a better sense of granularity in the heatmap. For the step size, we will keep it at 0.2 meters. Once we have the variables defined, we click on Fill table and the table on the bottom-left-hand corner of the window is now populated.

The red coloring indicates the areas that are subject to material removal, while purple indicates areas where material needs to be added. We are also free to customize the colors by left-clicking on them and choosing an option that suits our needs.

Heatmap

We are now ready to see the heatmap - we can toggle it On and Off - it takes a few moments for it to appear.

We are now able to see the surface heatmap, which illustrates which areas are subject to which type of grading procedure and at what intensity.

Spot levels

With Spot levels, we can define the density of the text element placement. This does not impact the accuracy of the grading procedure, but rather how many points are placed on the drawing to illustrate the calculations. The resulting elevations are colored based on the Surface comparison table. Toggle on the Spot levels by clicking the On button. Example below:

Export to CAD

Finally, we can also add a legend with the surface comparison table colors and range values into the drawing by clicking on Export to CAD and left-clicking on the drawing where we want to place this table. This is an accessible way to showcase the range of values and colors used for presentation purposes. Example below:

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