5 - planning earthwork

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Construction Engineering

CIV420H1

Fall 2014

Construction Equipment Management

(Planning Earthwork)


Construction Equipment ManagementPlanning Earthwork

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Planning for earthwork construction

• The goal of planning is to minimize the resourceexpenditures required to complete the project.

• Planning involves all of these:

• Inputs to prepare a plan and cost estimate:

1- Operational plan—

what is to be done, sequence2- Scheduling — when each operation is to be done

3- Cost estimating — what is the expected cost.

4- Resource planning—

what resources arerequired





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Inputs to prepare a plan and cost estimate:

1- Quantities involved (volume or weight)

2- Haul distances

3- Grades for all segments of the hauls.

• The constraints of planning are:

1- Requirements of contract documents.

2- Legal requirements (OSHA, licensing)

3- Physical and/or environment limits.

4- Climatic conditions.





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• Graphical presentation of earthwork:

Plan view — presents the horizontal alignment offeatures.

Source: Peurifoy and Schexnayder "Construction Planning, Equipment, and Methods”





5Source: Peurifoy and Schexnayder "Construction Planning, Equipment, and Methods”



Profile view — presents the vertical alignment offeatures.





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Cross section view — A view formed by a planecutting the work at right angles to its long axis.

Material volumes in a project that is linear in extentare usually determined from cross sections






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• Earthwork quantities:

• End-Area Determination

The general trapezoidal formula to calculate area:

wh

hhhh

Area nn

22

1210

sides parallel twothebetweencetandisw

sides parallel adjacent individual theof lengthstheh , ,h n0






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• Average End Area

The precision is about ± 1.0%

27 L

2 A A

cy yardscubicnet Volume 21

areasend respectivetheof sf feet squareinarea Aand A 21





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• Average Height

Source: Nunnally, S. W. Construction Methods and Management







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Soil volume characteristics

• Bank state: Natural

• Loose state: Excavated

• Compacted state: Compacted






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• Swell (%) =((bank density /loose density) -1) x 100

• Load factor = loose density/bank density

= 1/(1+swell)

• Shrinkage(%) = (1- (bank density/compact density) x 100

• Shrinkage factor = bank density /compact density

= 1- shrinkage



11Construction Engineering




• Swell and shrinkage factors



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• Earthwork volume sheet

Allows for the systematic recording of information and making the necessaryearthwork calculations.

The ordinate accounts only for material that must be transported beyondthe limits of the two cross sections.






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• Mass Diagram

The stations of a project versus the cumulative sum of excavation andembankment from some point of beginning of the project profile.






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• Mass Diagram

An effective tool for planning the movement of material on any project of

linear extent.

Provides information about:

1- Quantities of materials,

2- Average haul distances,

3- Types of equipment that should be considered.

When combined with a ground profile, the average slope of haul segmentscan be estimated.





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• Using Mass Diagram

• Balance linesA horizontal line that intersects the mass diagram in two places.

Constructed so that its length is the maximum haul distance for differenttypes of equipment.

The maximum haul distance is the limiting economical haul distance for aparticular type of equipment.






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• Balance linesA balance line of 5,000 ft was constructed for a large push-loaded scraper.Some hauls will approach the maximum haul distance while some others willbe short.

The average haul distance is placed one-third of the distance from balance

line in the direction of the high or low point of the curve.






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• Balance linesWhen there are multiple equipment to be utilized, balance lines should bedrawn to conform to their capabilities.

the average haul distance is placed midway between the balance lines.






19Source: Peurifoy and Schexnayder "Construction Planning, Equipment, and Methods”



• Average grade

%9.8100 ft 203 ft 18

fill thetocut the from going grade Average





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• Haul Distances






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• Haul Distances (graphically)An average haul line should be drawn though the vertical centroid of the areadefined between the mass diagram and the balance line.

The centroid of areas 1, and 2 is one-third of its altitude above the base.

Scaling from the mass diagram graph, haul distances 1, and 2 are 400, 350 ft.

For area 3, the half-point of its height is used to construct the average haulline which yields a distance of 12,200 ft.



Source: Peurifo y and Schexnayder "Construction Planning, Equipment, and Methods”

5 - planning earthwork

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