Putting Roads and Benches in a
Pit
©2012 Dr. B. C. Paul
Note – These slides contain screen shots from the program MineSight which
was created by Mintec. Credit for the program is given to Mintec. Additionally
these slides may be based in part on earlier work by the author and the
contents may be similar to portions of classes taught by Mintec in using their
software.
The Pit Designs Produced by
Economic Planner are Smooth
They lack the
Bench structure
And roads found
In real open pits.
We can add these
Features to fit a
Practical open pit
Mine.
Lets Start By Contouring What
We Have Now
I have prepared an open edit object to
Receive data
Now I will activate the contour tool.
The Contour Tool Dialog Opens
I will set it to contour elevation
Next I need to tell it what surface
To contour
I will pick the blue worm (which
Allows me to pick my surface
From the viewer. The red dot
Has me make my pick from
A file directory).
Click the Worm – Click the
Surface
Now We Click Preview to Check
it Out
Looks Good
Turn Off Other Surfaces and
Admire My Contour Set
Of course now I
Have to face the
Fact that it does
Not fit the road
And bench
Pattern of a real
Practical open
Pit.
Lets Start with a Simple – Well
Behaved Pit.
I have my stage 1 pit surface in my pit optimization file.
I Also Have Topographic
Contours of My Pit
I Zoom in and Query My Pit Bottom
Contour to Get Its Elevation
Pits With Toes, Crests, Berms and Roads
are Designed with the Pit Expansion Tool
Go to Tool and
Drop down the
Menu
Highlight and Click
Pit Expansion Tool
The Routine Will Help You Set
Up A New Geometry Object
Pick your File
Title
And hit open
You Need a Line For the Bottom
of Your Pit
Pick Digitize
Click Your Bottom
Contour
Confirm it is the right line
Hit Add
You Can Also Truly Digitize the
Base String (Sometimes you can draw a
more practical geometry for equipment)
Set the radio button to
Digitize (copying an
Existing contour is also
An option but those contours
Created by LG or Floating
Cone usually do not consider
Practical working spaces for
Your equipment).
Type in the elevation of your
Toe around the bottom of
Your pit
Click Add
Then begin to digitize your
Base string.
Now Drop to the Lower Box and Set
Your Pit Expansion Parameters
Specify the start
Elevation to match the
Bottom of the pit
You can tell it to do
A bunch of steps at
Once (I counted
Contours to know I
Wanted 19 benches)
Next Step Will Be to Set
Benching Parameters
Berm Width
Step Size
Starting
Elevation
Face
Slope
Pit Slope
Next I Click On the Required Tab
to Tell it How to Bench Up
You can choose
Which parameters to
Specify
2330 starting elev
I specified my 15 meter
bench,
A 72 degree slope
From the toe to crest
And a 42 degree
Over-all working slope
(I could have specified
Bench width and let
It figure the pit slope)
Indicate I want the pit to expand upward and outward.
Next I Open the Roads Tab
I Go to the Naming Field to Name
My Road
It tells me my road
Is unset
(surprise-surprise
I haven’t set it yet
So click Edit)
It Needs Me to Tell it Where to
Start the Road
Click on the point
Symbol and then
Point to the spot
To begin.
Enter the Road Parameters
Give it the starting
Level
The road width
The Grade (0.1 means
10%)
And the direction
Code 1= clockwise
The View Clicks Back to the Road
Tab Only Now the Road is Set
Go Back to the Expansion
Screen and Hit Preview
Oh Wow Cool!
Back Out and I Can See My
Road and the Toes and Crests
I can also see my road width pushed my pit back a little more and cut the
Over-all slope.
It Does However End at the Right
Level
I Have An Option to Fix That
Road Issue
I’ll tell it to dock the road with off of the bench width
Click Apply to Add that
Steepening Effect
We Can See We Have Taken a Nice
Chunk Out of Our Benches with the Road
It Gives Me A Chance to Name
And Save My Instruction Set
I Can Now Click Triangulate to Have it
Create a Pit Surface From My Toes and
Crests and Road
There is My Triangulated Pit With
A Lot of Stuff On at the Same
Time
Here is One Item – My Toes and
Crest Profile
Here is My Triangulated Surface
I Highlighted – Right Clicked and
Picked Properties
Then I used
Global Color to
Change My Surface
Color
A Picked Faces Only
To get the faces
Without the
Triangulation showing
If I Turn On My Pit2 Surface I Can See My
Benches Surface is Mostly A Little Below
the Lerch Grossman Surface
I Can Adjust the Lerch Grossman
Surface to be a Little See
Through
On Object Properties Click the Surfaces Tab and Use the Arrow to increase the
Transparency of the surface
Now I Can See My Design Pit Surface if
Very Close to the Lerch Grossman
Surface
That Worked Slick - But
• The pit was a simple cone shape
• It was a simple spiral road
• I wanted to road to make it to the
surface but did not care where it came
out.
• Everything worked on the pit expansion
tool
Common Bugaboo’s – I have no idea of
my elevation
Your base string goes onto the level
Indicated – not necessarily the level you
Are trying to work on.
Are you trying to expand from the level of your base string?
(if you are not you won’t like the result)
Issues and Solutions
• The Bottom of My Pit is so small there is no
way real equipment can work there.
Then start your pit a few levels up and/or
Digitize a base string that provides enough
Room and a workable geometry
(no it won’t exactly follow your theoretical
Pit but you said real equipment could not
Build that theoretical pit anyway).
Issues and Solutions
• I want my road to
come out at a
specific point on the
surface
• Set your base string
at the level you want
to come out.
Making a Road Come Out at a
Specific Point
“Expand” your pit downward
And inward – instead of from
The bottom up.
Making a Road Come Out At a
Specific Point
Edit your road to start at your chosen elevation
And then pick the starting point where you want
The road to come out.
(Then of course you click the exit point in
The viewer)
Dealing With Irregular Pit
Geometries
• Don’t try to expand your pit all the way up (or
down) at once.
Note that you can set how many
Benches to do at one time.
(You can even expand one bench
At a time)
You can use the Query tool to see the
Elevation of things in the viewer.
You can also preview anything you
Draw before you commit to it.
Dealing with Irregular Pit Geometry- This
Pit has Multiple Bottoms – One at 2072
and the Other at 2090
Dealing With Irregular Pit
Geometries
I don’t think I can
Get equipment in
That little hole at
2072
Dealing With Irregular Geometries
– Mutiple Pit Bottoms
First enter the elevation of the
Base string.
Click the radio button to digitize
The base string.
Then click the add button
Then digitize the base string.
Pay attention that you select
A geometry that is practical to
Dig out and work. Some types
Of cuts may have a tendency
To be unstable from a rock
Mechanics stand point. Try to
Add practicality while you
Digitize.
Note that I dropped the small
Pit at 2070 because there
Just was no room to work
Equipment.
I will similarly digitize the base string for the second bottom
Dealing with Irregular Geometries
– Multiple Pit Bottoms
Even if I have Base Strings at
Multiple levels
It will only expand structures up that
Start at or below the start level
Dealing With Irregular Geometries –
Multiple Pit Bottoms and Base Strings
Click the roads tab.
Select Add
(your first road name appears –
You can change it if you want.
It is initially undefined.
Click the edit button to define
Things like road start point,
Slope, and direction.
Set Road Starting Point for the
First Base String
Click the point icon to let the
Computer know you want to
Define the starting point for
The road.
Then point to and click the
Starting point for the road and
Right click to complete your
selection
A green dot appears and the
Coordinates show in the
Box.
Enter your starting elevation
Your road width
Your grade
Finally click ok to initialize your plan for the road
And 1 or 0 to indicate whether
The road should advance
Clockwise or counter clockwise
Since I’m Working Off Two Base Strings I
Initialize a road for my other Pit too
Click add to add a
Second road just like
I did the first.
I Complete the Process and Now
Have Two Road Starting Points
Note the old completed
Road point is showing
Yellow instead of green
I Click Preview and My Pit Expands Up One
Bench and I Can See Where My Road is Going
I Can Preview and Move Up
Again
As Expansion Continues Up the
Base Strings will Merge
At this point I notice my first dissatisfaction because I wanted the road to meet when the pits did which did not
Happen.
Oh – So I’m Having a Road
Come Out at the Wrong Place
• Maybe one of the pits I’ll have to
expand down so my roads merge.
This Raises the Issue of What If I
Want to do Something Unusual With
the Road
Like – Maybe I want the road to
Switchback
Note I have the ability to specify
Direction changes in a road at
Different elevations
What is this SB Business?
With no Switch Back Radius you
Will get a V shaped turn
SB parameters let you put in a smooth bend, control the grade through the switchback
And control the length of the road over which the grade control applies
SB Length Multiplier x (road width + SB Radius) = SB Length
What If I Want to Split a Road to
go in different directions?
Do a Zero Expansion
Then start a new road right at
The edge of the road you wish
To split off from.
What Happens If the Pit Has Huge
Push Backs at Higher Levels?
Consider Digitizing Another Base
String at a Higher Level
Set the elevation for
The higher string
Elevation
Click Add and digitize
As before.
The Smaller Pit is Engulfed in the
Expansion of the Larger
You Can Also Work With Large
Pushbacks by Editing Strings
I set my steps to 2,
Previewed to make
Sure I was happy,
And then applied.
Now I am going to
Hit the Edit String
Button.
It Asks Me To Confirm That I Want to
Work at the Toe of the 2558 Bench
It will pick the
Level for the next
Expansion up
As the default
That’s a good
Choice for me so
I will say OK
The Toe Line of the Next Bench
Turns Red and I Have Access to the
Menus
Go to The Polyline Menu
While there are many
Tools and options for
Editing polylines, one
That produces a
Smooth modification
Without breaking the
Polyline is
Substring
Smooth
(If you break the
Continuous polyline
And don’t put it back
Together the pit
Expansion tool will not
Recognize it for the
Next expansion)
Working the Substring Smooth
Substring smooth allows you to stretch out existing parts of the polyline to cover the push back – lets look at
How.
Pick You the Ends of the Line
You Will Stretch
Note that the
Substring smooth
Dialog is open and
The substring
Smooth function is
Active
Note it is calling for
Me to pick my
Endpoints
I pick the endpoints
I want to stretch
Between.
I Click on the Polyline Between
My Two Marked Stretch Points
Yellow arrow appear
I can move and
Stretch these arrows
To shape the line
I am stretching
In-between.
I Pull and Stretch With The Arrows to
Stretch My Polyline out to the
Pushback
Note that I can see
Where the line is
Stretching to by the
Dotted yellow line.
When I have things
Where I want them
I right click my mouse.
I Continue My Work
Note that it is unlikely
That I can fully shape
My toe to the desired
Push back in just
One step.
Eventually I Get My Toe Line
Stretched Out to Follow the Push
Back
I click save to
Save my
Masterpiece
The Completed Modified Toe Line
Turns Blue
Another Way to Adjust Strings for
Push-Backs
I’m going to “Edit
My Base String” to
Handle this push
Out of a bench.
Another thing I did
Was to create
Another horizontal
Gridset with grids
Every 15 meters to
Match the benches.
I then attached that
To the viewer so my
Viewing would be
Easier.
It Ask Me What I Want to Edit on
What Level
They had a pretty
Good idea I would
Want to edit the
Current level and
Move to the toe for
The next bench
Going up because
That is the default
Click Ok
The Pit Expansion Menu Shuts Down but
the Point and Polyline Menus are Available
I’m going to use
Point
Move
To move points on
The toe of the next
Bench out to where
They need to be.
I Drag Out the Points to Fit the
pushed out bench
To finish my
Effort I
1- Right Click My
Mouse (to tell it I’m
Through moving
Points)
2- I click on the
Weird save icon
To save the work
Whenever the
Program stares
At you and won’t
Let you do anything
Try right click save
My Base String is Now Moved
I set it to expand
Up 1 level
(because I know
There is another
Push out one bench
Up)
Human interest
Note that the program
Keeps track of
My base string
Expansion history
And shows me where
My other base strings
Are located.
Select My Shifted Base String for
the Expansion
I clicked copy
Then I clicked
Add
Then I clicked on
The base string
I will use for the
Expansion.
Yes it turned a
Pretty yellow to
Show what was
Picked.
I Click Preview, Check it Out, and
then Click Apply When I Like It.
I Jump Up One Bench Level to
See Where the Extra Push-out is.
Note I have reset
The viewer 2D to
The next bench
Level up
Note the program
Now has 2 base
Strings in the
History.
I Use the Edit Strings – Point – Move
Trick and Move My Toe Out to The
Bench
I Now Copy My Modified Base
String and Expand Up 6 Benches
Yup It Looks Like I’m Getting a Good
Fit On My Way Up This Time
Now I Have to Push My Base String
Out Again to Get a Bench That Pushes
out
Remember I set my
2D viewer plane to
The bench level I
Was working on
I picked edit string
Then I used the point
Menu
I used the point
Function to move
Points on the base
String out to bench
Trace from my
MSOPIT
I Thought Expanding up 15 Benches
Would Get Me Above the Surface
It didn’t
I could have
Avoided the problem
By doing a query
Before I started so
I would have known
How high the
Surface was just
Like I new how
Many benches to
Expand up between
Push outs.
I Go to the Top of My Pit and Pick
the Highest Toe to Do One More
Expansion
Oh Ya – This is Working
The Problem of Roads Suddenly
Terminating During Expansion
Rule #1 – A Road Cannot Ascend
Faster or Slower than the ground
underneath it.
No actually roads
cannot hover in the
air
No actually roads cannot
Just drive into the side of
A mountain without a tunnel
or slot
In this case I tried to hover the road in the
air. I can just restart the road on the other
side of the flat area
I will restart on the
Next bench.
Since this is a large
Working bench area
I will start on the other
Side
This time I will make
It go counter-clockwise
Click Ok
Rule #2 – If the Ground Turns
Faster than the road can – it is
not an option to have the road
hover in the air.
You can see in this case the road
Could not turn on that pointy spike
Of rock.
(In this case I think a pointy nose of
Rock is a slope stability hazard – I’m
Going to do some line smoothing).
Another alternative would be to start
The road at a different point.
Another alternative would be to use
A narrower road that could turn
Sharper.