Estimating Earthwork - kontrak prosedur 2

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Earthwork includes: 1. Excavation 2. Grading: Moving earth to change

elevation 3. Temporary shoring 4. Back fill or fill: Adding earth to

raise grade 5. Compaction: Increasing density 6. Disposal

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A. Job conditionsMaterial typeWater level and moisture contentJob sizeLength of haulHaul road condition (accessibility and

load restrictions)

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B. Management conditionsEquipment conditions and

maintenance practicesSkills of work force and managementPlanning, supervision and

coordination of work.

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J ob Conditions** Excellent Good Fair Poor

Excellent 0.84 0.81 0.76 0.70

Good 0.78 0.75 0.71 0.65

Fair 0.72 0.69 0.65 0.60

Poor 0.63 0.61 0.57 0.52

Management Conditions*

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Meter cube m3 (bank, loose, or

compacted)

Bank (BCY): Materials in its natural state before disturbance (in-place, in-situ)

Loose (LCY): Material that has been compacted or disturbed or loaded

Compacted (CCY): Material after compaction

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1.0

1.25

0.90

1.0 METER CUBE IN NATURAL CONDITION (IN-PLACE YARD)

1.25 METER CUBE AFTER DIGGING (LOOSE YARDS)

0.90 METER CUBE AFTER COMPACTED (COMPACTED YARDS)

In place CompactedLoose

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Bank: VB

Bank Meter Cube (BMC)Density B Lb /BMC

Loose: VL

Loose Meter Cube (LMC)Density L Lb/LMC

Compacted: Vc

Compacted Meter Cube (CMC)Density C LB/CMC

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Swell:A soil increase in volume when it is excavated.

Swell (%) = ( - 1) x 100

Load factor =

Bank Volume = Loose volume x Load factor

Loose densityBank density

Bank densityLoose density

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Shrinkage:

A soil decreases in volume when it is compacted

Shrinkage (%) = (1 - ) x 100

Shrinkage factor = 1 - Shrinkage

Compacted volume

= Bank volume x Shrinkage factor

Bank densityCompacted density

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Material

Loose

(kg/m3)

Bank

(kg/m3)Swell (%)

Load Factor

Clay, dry 1,604 2,024 26 0.79Clay, wet 2,062 2,731 32 0.76Clay and gravel, dry 1,833 2,139 17 0.85Clay and gravel, wet 1,986 2,368 17 0.85Earth, dry 1,693 2,177 29 0.78Earth, moist 1,841 2,353 28 0.78Earth, wet 2,101 2,582 23 0.81Gravel, wet 2,123 2,398 13 0.88Gravel, dry 2,360 2,765 17 0.85Sand, dry 1,986 2,230 12 0.89Sand, wet 2,368 2,689 13 0.88Sand and gravel, dry 2,215 2,483 12 0.89Sand and gravel, wet 2,597 2,865 10 0.91

Exact values will vary with grain size, moisture content, compaction, etc. Test to determine exact values for specific soils.

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Initial

Soil Type Soil Condition Bank Loose CompactedClay Bank 1.00 1.27 0.90

Loose 0.79 1.00 0.71Compacted 1.11 1.41 1.00

Common earth Bank 1.00 1.25 0.90Loose 0.80 1.00 0.72Compacted 1.11 1.39 1.00

Rock (blasted) Bank 1.00 1.50 1.30Loose 0.67 1.00 0.87Compacted 0.77 1.15 1.00

Sand Bank 1.00 1.12 0.95Loose 0.89 1.00 0.85Compacted 1.05 1.18 1.00

Convrted to:

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Angle of Repose2’-0”or more

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For Sloping Sides of Excavation

OriginalGround Line

Solid

Rock

, Sla

te o

r C

em

ente

d S

and a

nd G

ravel

(90

Deg.)

Com

pact

ed A

ngul

ar G

rave

ls

1/2:

1 (6

3 D

eg.)

Reco

mm

ende

d Sl

ope

for A

vera

ge S

oils

1:1

(45

Deg.)

Compacted Sharp

Sand

1 1/2 :1 (3

3 Deg.)

Well Rounded Loose Sand

2:1 (26 Deg.)

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1. End Area Method

2. Contour Line/ Grid Method

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Used in sites where length is much greater than width

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1. End Area Method

a.Take cross-sections at regular intervals, typically, 10m intervals.

b.Calculate the cross-section end areas

c.The volume of earthwork between sections is obtained by taking the average of the end areas at each station in square meter.

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Fill

Cut

80

82

84

86

88

80

84

86

88

82

78

A’ B’ C’ D’ E’ F’

A B C D E F10 10 10 10 10

50m

30

m

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80

78

76

82

80

78

84

82

80

86

84

88

86

90

88

78.5

80.3

82.3

84.2

86.2

88.2

Sec. A’- A

Sec. B’- B

Sec. C’- C

Sec. D’- D

Sec. E’- E

Sec. F’- F

Pro

ject

Cro

ss S

ect

ion

s

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80

79

78

77

76

79.5

78.5

76.7

Section A’- A

Area = = 173.7193 x 1.8

2

Area = = 53.5107 x 1.0

2

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82

81

80

79

78

81.8

80.3

76.7

Section B’- B

Area = = 189.0210 x 1.8

2

Area = = 67.590 x 1.5

2

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Section Emb (CCY) Exc. (BCY) Exc. x B/C(CCY)

Net Exc.(CCY)

Cum Exc(CCY)

A-B 672 224 254 - 418 - 418B-C 567 441 499 - 68 - 486C-D 215 791 896 681 195D-E 0 1031 1167 1167 1362E-F 0 1222 1384 1384 2746

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Used for parking lots and site “leveling”

Grid size from 10mx10m to 50mx50m

the greater the terrain variance the smaller the grid

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Step l

Determine by visual study of the site drawing if the net total will be an import (more fill required than cut) an export (less fill required than cut) or a blend (cut and fill about equal)

Step 2Determine the pattern of calculation points or grid size.

Step 3 Determine elevations at each calculation location, the corners of each grid.

Step 4 Calculate the cubic yards of cut or fill required in each grid cell.

Step 5Add the individual Grid Cell quantities together to arrive at the total cut, total fill volume and the import or volume export yardage required for the job.

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A B C D E F87.6 88.6 89.4 90.4 91.6 93.2

G H J K L M87.4 88.2 89.5 90.6 91.6 92.7

N O P Q R S87.2 87.7 89.0 90.4 91.3 92.0

87.6 88.5 89.3 90.3 91.5 95.0

94.3

93.5

93.1

A B C D E F G60m

88’ 89’ 90’ 91’ 92’ 93’ 94’

No ScaleNotes:1. Bring the entire site to elevation 90.2. All grids are 10m x 10m = 100 sq m3. Present contours

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PurposeGrade the entire site to grade 90’

Quick and DirtyAssume one gridExisting 90.50Proposed 90.00Cut 0.50

Total Cost = = 1.851m310 x 10 x 0.5027

10m

10

m

NeedFill

Need

Cut

90'

90' 91'

90.5'

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Average elevation

=

= 88.08change = 90-88.08

= 1.92m3

If we choose the grid size to be 10mx10m

87.6+88.5+87.6+88.64

87.6

88.6

87.687.6