CE 3220 Lecture 7-2 Earthwork.pdf

8/17/2019 CE 3220 Lecture 7-2 Earthwork.pdf

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Planning for EarthworkConstruction

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 recommendedto relate the physical site

characteristics to the work details.


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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

available

engineering and

design data.

Must be as accurate as possible,

and should be based on all

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 showearthwork construction features:

– Plan view

– Profile view

– Cross section view


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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


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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 usecommercial computer software

and digitizing tablets to calculate

cross section end areas.

www.trimble.com/paydirt.html

www.agtek.com/about.shtm

End Area

Determination

Other methods include the use of a

planimeter, subdivision of the area

into geometric figures withdefinite formulas for areas

(rectangles, triangles, parallelograms

and trapezoids), and the use of the

trapezoidal formula.

Trapezoidal

Computations

If the calculations must be made byhand, the area formula for a triangle

and a trapezoid are used to computethe volume.

Area of a triangle = ½ hw

Area of a trapezoid = w )hh(

2

21


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General Trapezoidal

Formula

Area = wh

h...hhh n

)n(

22

121

0

Average End Area

Method

Volume [net cy] =

Assumes that the ground between

the two end areas changes in a linear

fashion.

272

21 L ) A A(

Average End Area

Average End Area


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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 anddeposited 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).


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Mass Diagram

Aids in identifying:

• Where to utilize specific typesof equipment,

• Where quantities of material

are required,

• Average haul distance,

• Haul grades.

Earthwork Volume

Calculation Sheet

An earthwork volume sheet, caneasily 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.


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Area of cut. Column 2 is the cross-

sectional 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-end-

area formula, This is a compacted

volume.


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STRIPPING

For cut sections subtract the stripping.

STRIPPING

For fill sections the stripping is a cut

quantity; plus an equal amount mustbe added to the embankmentquantity.

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. Topsoilmaterial 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 additionalrequirement for fill material, compacted

volume of fill.


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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 cutvolume (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 volumequantities.

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 thatis available (cut is

positive) or required

(fill is negative) withinstation increments after

intrastation balancing.


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Column 12 is the running total of

column 11 values from some point of

beginning on the project profile.

Mass Ordinate MASS DIAGRAM PLOTTING

0

500

- 500

1000

- 1000

Horizontal scale (stations)

0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00

MASS DIAGRAM PLOTTING

STATION 0+50- 138 CY

1000

500

0

- 500

- 1000

0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00


0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00

STATION 1 +00- 405 CY

500

1000

0

- 500

- 1000


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STATION 3 +50518 CY500

1000

0

- 500

- 1000

0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00


CONNECT THEPOINTS

500

1000

0

- 500

- 1000

0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00

MASS DIAGRAM

0

500

-500

1000

- 1000

0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00

Descending lines

Embankment requirements

exceeds excavation quantity.

MASS DIAGRAM

0

500

-500

1000

- 1000

0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00

Ascending lines

Excavation exceeds embankmentrequirements


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0

-500

-1000

500

1000

1 +0 0 2 +0 0 3 +0 0 4 +0 0 5 +0 0 6 +0 0 7 +0 0 8 +0 0

V

O

L

U

M

E

C

C

Y

STATIONS

FILL CUT

CUT FILL

MASS DIAGRAMMASS DIAGRAM

0

500

-500

1000

- 1000

0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00

Zero balance line

Excavation quantity equalsembankment requirement..

MASS DIAGRAM

Maximum is where the cuttransitions into fill.

Minimum is where the fill

transitions into cut.

Maximum and minimum points

MASS DIAGRAM

0

500

-500

1000

- 1000

0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00

Transition point

Maximum and minimum points


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MASS DIAGRAM

Final position

Stations 0 1 2 3 4 5 6 70 1 2 3 4 5 6 7

cy500

0

410 cywaste

Above the zero line indicates waste.

Below the zero line indicates borrow.

90 cyborrow

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,

pushing material

Up to 300 ft

Push-loaded scrapers 300 to 5,000 ft

Trucks > than 5,000 ft


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Mass Diagram With a Balance Line

Haul Distances

Page 81

Haul Distances

Haul No. 3 quantity -17,080

Average haul = area / quantity (cy)

Haul No. 1 quantity?

Haul Distance

0+00 h0 0

1+ 00 h1 -3, 631 -3, 631 -1, 816

2+ 00 h2 -1 3, 641 -17, 272 -8, 636

3 +0 0 h 3 -1 7,08 0 -3 0,72 1 - 15 ,3 61

4 +0 0 h 4 -1 7,08 0 -3 4,16 0 - 17 ,0 80

5 +0 0 h 5 -1 7,08 0 -3 4,16 0 - 17 ,0 80

6 +0 0 h 6 -1 7,08 0 -3 4,16 0 - 17 ,0 80

7 +0 0 h 7 -1 7,08 0 -3 4,16 0 - 17 ,0 80

8 +0 0 h 8 -1 7,08 0 -3 4,16 0 - 17 ,0 80

9 +0 0 h 9 -1 7,08 0 -3 4,16 0 - 17 ,0 80

10+00 h10 -17,080 -34,160 -17,080

11+00 h11 -17,080 -34,160 -17,080

12+00 h12 -17,080 -34,160 -17,080

13+00 h13 -17,080 -34,160 -17,080

1 4+ 00 h 14 - 8,50 2 -2 5,58 2 - 12 ,7 91

15+00 h15 0 -8,502 -4,251


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0+00 h0 0

1+00 h1 -3,631 -3, 631 -1,816

2+ 00 h2 - 13, 641 - 17, 272 - 8, 636

3 +0 0 h 3 -17 ,0 80 -30, 72 1 -15 ,3 61

4 +0 0 h 4 -17 ,0 80 -34, 16 0 -17 ,0 80

5 +0 0 h 5 -17 ,0 80 -34, 16 0 -17 ,0 80

6 +0 0 h 6 -17 ,0 80 -34, 16 0 -17 ,0 80

7 +0 0 h 7 -17 ,0 80 -34, 16 0 -17 ,0 80

8 +0 0 h 8 -17 ,0 80 -34, 16 0 -17 ,0 80

9 +0 0 h 9 -17 ,0 80 -34, 16 0 -17 ,0 80

1 0+00 h1 0 -17 ,0 80 -34, 16 0 -17 ,0 80

1 1+00 h1 1 -17 ,0 80 -34, 16 0 -17 ,0 80

1 2+00 h1 2 -17 ,0 80 -34, 16 0 -17 ,0 80

1 3+00 h1 3 -17 ,0 80 -34, 16 0 -17 ,0 80

1 4+00 h 14 -8, 50 2 -25, 58 2 -12 ,7 91

15+00 h15 0 -8,502 -4,251

-213,654

12.51

Area under diagram

Average haul No. 3 stations

cy08017

cysta654213

,

. ,

Haul

Distance

Consolidated Average Hauls

Using the individual average hauls and

the quantity associated with each, aproject 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.


Stations

Haul 1 11,459 bcy 3+51 40,221 sta-cy

Haul 2 5,590 bcy 3+35 18,727 sta-cyHaul 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


Stations

Haul 1 11,459 bcy 3+51 40,221 sta-cy

Haul 2 5,590 bcy 3+35 18,727 sta-cy17,049 bcy 58,948 sta-cy

58,948 sta-cy = 3.5 stations

17,049 bcy

Haul 3 17,080 bcy 12.5 stations


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Pricing Earthwork

Operations

The cost of earthwork operationswill 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

Haul, dump, return

Spread &

compact