GeoTech Drillholes and Strata

This lesson creates and processes drillhole data in the GeoTech module.

1. This drillhole lesson builds on the results of the Takeoff/SiteNET Basics tutorial. Before continuing with this tutorial, complete that tutorial up through the Make Existing Ground Surface/Make Design Surface section of that tutorial. When the Takeoff/SiteNET Basics tutorial is completed, we're now ready to add drillholes for the drawing as shown below:
   
2. Activate the GeoTech menu via Settings -- Carlson Menus -- GeoTech Menu. Our initial task will be to establish a desired drillhole symbol and the default strata names. Issue the Drillhole -- Define Drillhole and Strata Settings (aka Define Drillhole) command to display the dialog box similar to that shown below:
   
   For this tutorial, we are interested in rock quantities and we need to define two strata:
   1. DIRT (material above the rock), and,
   2. ROCK
   Click the Add button to create a material strata as described below and click OK when ready:
   
   Next, pick the Add button again. This time, fill out the dialog with a strata name of "ROCK" and use the information below to add the second strata material into the project and click OK when complete:

   Strata Definitions

   Values	Strata 1	Strata 2
   Name	DIRT	ROCK
   Density	80	165
   Swell Factor	1.10	1.15
   Model Values	By Elevation	By Elevation
   Modeling Method	Inverse Distance - Power 2	Inverse Distance - Power 2

   NOTE: There are three options of modeling methods:
   • Inverse Distance will not carry trends and the calculated strata model will never be higher or lower than the original drillhole data and uses a weighted average of the drillhole data. In general, closer drillholes are weighted more than drillhole farther away:
     • Inverse Distance - Power 2 will weigh drillholes more that are further away.
     • Inverse Distance - Power 3 will weigh drillholes less that are further away.
   • Linear Least Squares extrapolates trends and allows for a strata model to create new highs and lows that don't appear in the original drillhole data.
   The Strata Materials in the main dialog need to be in top to bottom order. To change the order, highlight a strata name and use the Move Up or Move Down buttons. In this case, we want DIRT then ROCK. Click OK from the main dialog.
3. There are two different methods for entering drillhole data:
   • Drillhole Import which reads the drillhole data from a text file. This command supports customizing the sequence of drillhole data fields to match the format of the text file. This process is discussed in the GeoTech Reports tutorial.
   • Place Drillhole creates the drillholes at picked positions in the drawing and enters the data in a dialog.
   For this tutorial, issue the Drillhole -- Place Drillhole command. When prompted:
   
   Station/<Pick Drillhole Location>: pick a location northeast of the building pad as shown below:
   
   A dialog box similar to that shown below appears. The Surface Elevation is automatically filled in using the Existing Ground Surface. The Drillhole Name, Water Table Elevation and Description are optional. The list of strata defaults to the strata defined in Drillhole/Strata Settings. Each strata defaults to a thickness of zero.
   
   Select/Highlight the DIRT entry and click the Edit button to display a secondary dialog box similar to that shown below:
   
   For this location, indicate the DIRT strata has a Thickness of 2 (press the Tab key to see the updated values) and then click Next Strata.
   
   For this example, we only know the depth to the top of rock depth and not the total rock thickness. We will treat all cut below the top of rock as ROCK strata. So we'll set the rock thickness deep enough to be lower than the Maximum Cut on site. In this case, indicate the ROCK strata has a Thickness of 15 (press the Tab key to see the updated values and then click Return to display a dialog box similar to that shown below:
   
   Complete the remaining values as desired and click Save. When prompted:
   
   Pick Drillhole Location (Enter to end): press Enter
   
   NOTE: If you had known the coordinates for the drillhole, you can type in the Easting,Northing format instead of picking on the screen.
   
   Now let's locate two more drillholes using a different method. Return to the Define Drillhole and Strata Settings command and set the changes as illustrated below and click OK when ready:
   
   Re-issue the Place Drillhole again and when prompted:
   
   Station/<Pick Drillhole Location>: pick a position in the lower parking lot
   Strata DIRT Thickness: type 1.5 and press Enter (complete any remaining items for DH2 and click Save)
   Pick Drillhole Location (Enter to end): pick a position left of the main building
   Strata DIRT Thickness: type 3 and press Enter (complete any remaining items for DH3 and click Save)
   Pick Drillhole Location (Enter to end): press Enter
   
   Now that the drillholes are in the drawing, we can explore the creation of sub-surface stata models.
4. To make the strata triangulation surfaces, run the StrataCalc -- Make Strata Surfaces command. There are no prompts for this routine. The strata surfaces are modeled from the drillholes and saved with the project. The file names for the strata surfaces use the drawing name plus -ch# where the # is the strata sequence number. For this example, the file names will be Takeoffdemo1-ch1 for bottom of DIRT and Takeoffdemo1-ch2 for bottom of ROCK. Now that the strata surfaces are created, there are several Takeoff/Construction routines that will use these surfaces including (but not necessarily limited to):
   • Calculate Total Volumes
   • Calculate Volumes Inside Perimeter
   • Define Topsoil Depths
   • Cut/Fill Labels
   • Surface Inspector
   • Quick Profile
   • Trench Network Quantities
5. Let's see where our ROCK cut locations are. Issue the StrataCalc -- Draw Strata Cut Color Map command. When prompted:
   
   Select Strata to Process: indicate the ROCK surface as illustrated below:
   
   Select point for color legend (Enter for None): pick a location of your choosing (top center of the legend)
   Legend size <10.0>: press Enter
   Label all zones or summary [All/<Summary>]? press Enter
   
   This command compares the design surface with the strata surface to make a cut color map of the cut depths for the strata. This command is one way to verify that the strata surfaces are modeled correctly. The result should be similar to that shown below:
   
   Optional: Remove the Strata Cut Color Map through the StrataCalc -- Erase Strata Cut Color Map command.
6. Let's explore the impact of the ROCK cut in terms of its contribution to the project volumes. Activate the Construction menu via Settings -- Carlson Menus -- Construction Menu. Next, issue the Takeoff -- Calculate Total Volumes command to display a dialog box similar to that below:
   
   When strata surfaces are defined, the volume routine will separate the cut volume into the different strata. Depth Zones (2 ft zones in this case) can also be defined in this command. Set the values as shown above and click OK when ready. The resulting dirt and rock quantities are summarized in a report similar to that shown below:
   
   Review and click the Exit (Doorway) button when complete.

This completes the tutorial: GeoTech Drillholes and Strata.