Transcript Maricopa Conunty - Civil Engineering Society @ Legenda

Chapter 3
Planning for Earthwork
Construction
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Planning for Earthwork
Construction
Every construction project is a
unique undertaking. Therefore,
planning is undertaken to
understand the problems and to
develop courses of action.
Planning Earthwork
Construction
•
•
•
•
•
Review the Contract Documents
Study the plans
Plan the Work
Perform quantity take-off
Determine costs
Planning Earthwork
Construction
A site visit is strongly recommended
to relate the physical site
characteristics to the work details.
Planning Earthwork
Construction
After the site visit is completed, the
planner determines the quantity of
materials that will have to be furnish
or move.
The takeoff or
"quantity survey."
Quantity Take-off
Must be as accurate as possible,
and should be based on all
available
engineering and
design data.
Planning Earthwork
Construction
During the takeoff, the planner
must make decisions concerning:
– equipment needs
– sequence of operations
– and crew size
Graphical Presentation
of Earthwork
Three kinds of views are presented in
the contract documents to show
earthwork construction features:
– Plan view
– Profile view
– Cross section view
Plan View
The plan view is looking down on the
proposed work and presents the
horizontal alignment of features
Profile View
The profile view is a cut view typically
along the centerline of the work.
It presents
the vertical
alignment of
features.
Cross Section View
A view formed by a plane cutting the
work at a right angle to its long axis
– When the ground surface is regular,
sections are typically taken at every
full station (100 ft)
– When the ground is irregular,
sections must be taken at closer
intervals & at points of change
Earthwork
Quantities
Earthwork computations involve:
• Calculation of earthwork
volumes
• Balancing of cuts and fills
• Planning of the most
economical material hauls.
End-Area
Determination
Most organizations use
commercial computer software
and digitizing tablets to calculate
cross section end areas.
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End-Area
Determination
Other methods include the use of a
planimeter, subdivision of the area
into geometric figures with
definite formulas for areas
(rectangles, triangles, parallelograms
and trapezoids), and the use of the
trapezoidal formula.
Trapezoidal
Computations
If the calculations must be made by
hand, the area formula for a triangle
and a trapezoid are used to compute
the volume.
Area of a triangle = ½ hw
( h1  h2 )
w
Area of a trapezoid =
2
General Trapezoidal
Formula
hn 
 h0
Area =   h1  h2  ...  h( n1 )    w
2
 2
Average End Area
Method
Volume [net cy] =
( A1  A2 ) L

2
27
Assumes that the ground between
the two end areas changes in a linear
fashion.
Average End Area
Average End Area
Average End Area
Net Volume
• Bank cubic yards (bcy)
• Loose cubic yards (lcy)
• Compacted cubic yards (ccy)
bcy
lcy
ccy
Mass Diagram
Earthmoving is basically an
operation where material is
removed from high spots and
deposited in low spots with the
“making up” of any deficit with
borrow or the wasting of excess
cut material.
Mass Diagram
The mass diagram is an excellent
method of analyzing linear
earthmoving operations.
It is a graphical means for
measuring haul distance (stations)
in terms of earthwork volume
(cubic yards).
Mass Diagram
Aids in identifying:
• Where to utilize specific types
of equipment,
• Where quantities of material
are required,
• Average haul distance,
• Haul grades.
Earthwork Volume
Calculation Sheet
An earthwork volume sheet, can
easily be constructed using a
spreadsheet program. It permits
a systematic recording of
information and completing the
necessary earthwork calculations
Earthwork Volume
Calculation Sheet
Table 3.1, page 73
Stations. Column 1 is a listing of all
stations at which cross-sectional areas
have been recorded.
Area of cut. Column 2 is the crosssectional area of the cut at each station.
Usually this area must be computed
from the project cross sections.
Area of fill. Column 3 is the cross-sectional
area of the fill at each station. Usually this
area must be computed from the project
cross sections. Note there can be both cut
and fill at a station.
Volume of cut. Column 4 is the volume of
cut between the adjacent preceding
station and the station. This is a bank
volume.
Volume of fill. Column 5 is the volume of
fill between the adjacent preceding
station and the station. The average-endarea formula, This is a compacted
volume.
STRIPPING
For cut sections subtract the stripping.
STRIPPING
For fill sections the stripping is a cut
quantity; plus an equal amount must
be added to the embankment
quantity.
Column 6 is the stripping volume of
topsoil over the cut between the
adjacent preceding station and the
station. This represents a bank
volume of cut material. Topsoil
material is not suitable for use in the
embankment.
Column 7 is the stripping volume of
topsoil under the fill between the
adjacent preceding station and the
station. The stripping is a bank volume
but it also represents an additional
requirement for fill material, compacted
volume of fill.
Column 8 is the total volume of cut
material available for use in embankment
construction. It is derived by subtracting
the cut stripping (column 6) from the cut
volume (column 4), both are bank volume
quantities.
Column 9 is the total volume of fill
required. It is derived by adding the fill
stripping (column 7) to the fill volume
(column 5), both are compacted volume
quantities.
Column 10 is the total fill volume
converted from compacted volume to
bank volume
Column 11 is the
difference between
column 10 and column
8. This indicates the
volume of material that
is available (cut is
positive) or required
(fill is negative) within
station increments after
intrastation balancing.
Mass Ordinate
Column 12 is the running total of
column 11 values from some point of
beginning on the project profile.
MASS DIAGRAM PLOTTING
1000
500
0
- 500
- 1000
0 + 00
1 + 00
2 + 00
3 + 00
4 +00
5 + 00
Horizontal scale (stations)
6 + 00
MASS DIAGRAM PLOTTING
1000
STATION 0+50
- 138 CY
500
0
- 500
- 1000
0 + 00
1 + 00
2 + 00
3 + 00
4 +00
5 + 00
6 + 00
MASS DIAGRAM PLOTTING
1000
500
STATION 1 +00
- 405 CY
0
- 500
- 1000
0 + 00
1 + 00
2 + 00
3 + 00
4 +00
5 + 00
6 + 00
MASS DIAGRAM PLOTTING
1000
STATION 3 +50
518 CY
500
0
- 500
- 1000
0 + 00
1 + 00
2 + 00
3 + 00
4 +00
5 + 00
6 + 00
MASS DIAGRAM PLOTTING
CONNECT THE
POINTS
1000
500
0
- 500
- 1000
0 + 00
1 + 00
2 + 00
3 + 00
4 +00
5 + 00
6 + 00
MASS DIAGRAM
1000
Embankment requirements
exceeds excavation quantity.
500
0
-500
- 1000
Descending lines
0 + 00
1 + 00
2 + 00
3 + 00
4 +00
5 + 00
6 + 00
MASS DIAGRAM
1000
Ascending lines
500
0
-500
- 1000
Excavation exceeds embankment
requirements
0 + 00
1 + 00
2 + 00
3 + 00
4 +00
5 + 00
6 + 00
1500
M ASS DIAGRAM
MASS DIAGRAM
1000
CUT
500
V
O C
L C
U Y
M
E
FILL
0
-500
FILL
CUT
-1000
1+00
2+00
3+00
4+00
5+00
S TATIONS
6+00
7+00
8+00
MASS DIAGRAM
1000
500
Zero balance line
0
-500
- 1000
0 + 00
Excavation quantity equals
embankment requirement.
1 + 00
2 + 00
3 + 00
4 +00
5 + 00
6 + 00
MASS DIAGRAM
Maximum and minimum points
 Maximum is where the cut

transitions into fill.
Minimum is where the fill
transitions into cut.
MASS DIAGRAM
1000
Maximum and minimum points
500
0
-500
- 1000
Transition point
0 + 00
1 + 00
2 + 00
3 + 00
4 +00
5 + 00
6 + 00
MASS DIAGRAM
Final position
410 cy
waste
500
cy
0
0
1
2
3
4
5
Stations
6
7
90 cy
borrow
Above the zero line indicates waste.
Below the zero line indicates borrow.
MASS DIAGRAM
Is a graphical means for measuring
haul in terms of station yards.
• Ascending lines?
•
•
•
•
Descending lines?
Crossing the zero volume line?
Max. and min. points?
Final position?
Economical Haul Distances
Machine type
Economical
haul distance
Large dozers,
Up to 300 ft
pushing material
Push-loaded scrapers 300 to 5,000 ft
Trucks
> than 5,000 ft
Mass Diagram With a Balance Line
Haul Distances
Page 81
Haul Distances
Average haul = area / quantity (cy)
Haul No. 3 quantity -17,080
Haul No. 1 quantity?
Haul Distance
0+00
1+00
2+00
3+00
4+00
5+00
6+00
7+00
8+00
9+00
10+00
11+00
12+00
13+00
14+00
15+00
h0
h1
h2
h3
h4
h5
h6
h7
h8
h9
h10
h11
h12
h13
h14
h15
0
-3,631
-13,641
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-8,502
0
-3,631
-17,272
-30,721
-34,160
-34,160
-34,160
-34,160
-34,160
-34,160
-34,160
-34,160
-34,160
-34,160
-25,582
-8,502
-1,816
-8,636
-15,361
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-12,791
-4,251
Haul
Distance
213,654sta.  cy
17,080cy
0+00
1+00
2+00
3+00
4+00
5+00
6+00
7+00
8+00
9+00
10+00
11+00
12+00
13+00
14+00
15+00
h0
h1
h2
h3
h4
h5
h6
h7
h8
h9
h10
h11
h12
h13
h14
h15
0
-3,631
-13,641
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-8,502
0
-3,631
-17,272
-30,721
-34,160
-34,160
-34,160
-34,160
-34,160
-34,160
-34,160
-34,160
-34,160
-34,160
-25,582
-8,502
Area under diagram
Average haul No. 3 stations
-1,816
-8,636
-15,361
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-17,080
-12,791
-4,251
-213,654
12.51
Consolidated Average Hauls
Using the individual average hauls and
the quantity associated with each, a
project average haul can be calculated.
Consider the three hauls and their sum
of vertical’s average haul distances. By
multiplying each haul quantity by its
respective haul distance a station-yard
value can be determined.
Consolidated Average Hauls
Stations
Haul 1 11,459 bcy 3+51 40,221 sta-cy
Haul 2 5,590 bcy 3+35 18,727 sta-cy
Haul 3 17,080 bcy 12+51 213,654 sta-cy
34,129 bcy
272,602 sta-cy
272,602 sta-cy = 8.0 stations
34,129 bcy
Consolidated Average Hauls
Stations
Haul 1 11,459 bcy 3+51 40,221 sta-cy
Haul 2 5,590 bcy 3+35 18,727 sta-cy
17,049 bcy
58,948 sta-cy
58,948 sta-cy = 3.5 stations
17,049 bcy
Haul 3 17,080 bcy 12.5 stations
Pricing Earthwork
Operations
The cost of earthwork operations
will vary with the kind of soil or
rock encountered and the methods
used to excavate, haul, and place
the material in its final deposition.
Spreading Dumped
Embankment
Material with a Dozer
Water Truck and Roller used to
Compaction Embankment
Material
Three-link Earthwork
System
Excavate & load
Spread &
compact
Haul, dump, return