REVIEW - EARTH WORK

Fall 2011

STEPS FOR EARTH WORK COMPUTATION

Define Typical Cross Section

Apply Typical Cross Section:

Every Station

Station at pluses (ground breaks)

PT and PC

Where profile change from cut to fill or vise versa

Compute Area for each Cross Section

Compute Volumes between Cross Section

Typical Cross Section

Harbin (1998) Figure 20.2

Application of Typical Cross Section

Wright and Dixon (2004) Fig 13-5

Application of Typical Cross Section

Sections at Pluses

Harbin (1998) Figure 20.3

Application of Typical Cross Section

Harbin (1998) Figure 20.4

Transition

Excavation & Grading Handbook (http://www.electrical-contractor.net/The_Store/CR/Exc&Grading_Hbk_Preview.htm)

Side Slope

Plotting Cross Sections

Harbin (1998) Figure 20.6

Computing Areas for Cross Sections

McCormack (1985) Figure 13-3

Computing Areas for Cross Sections

McCormack (1985) Figure 13-3

Computing Volumes

1 21 2

27

L A AV

Average-End-Area

Where,V = volume (cu yd)A = area end sections (ft3)L = distance between end

sections (ft)

1 21 2V L A A

Where,V = volume (m3)A = area end sections (m2)L = distance between end

sections (m)

U.S. Units

Metric

Note: 1 yd3 = 27 ft3

Computing Volume - Example

Determine the earthwork volume between Stations 100 and 101 using the average area method if the road width is 30 ft. The cut side slopes are 2 : 1.

Station Left Center Right

100+00 C8.031.0

C6.00.0

C5.025.0

101+00 C6.027.0

C4.00.0

C2.019.0

Computing Volume - Example

Determine the earthwork volume between Stations 100 and 101 using the average area method if the road width is 30 ft. The cut side slopes are 2 : 1.

Cross Section at 100+00

Computing Volume - Example

Determine the earthwork volume between Stations 100 and 101 using the average area method if the road width is 30 ft. The cut side slopes are 2 : 1.

Area at Station 100+00

1

1

21

4 230 6.08.0 5.0 31.0 25.0

4 2

265.5

L R L R

w cA h h d d

A

A ft

Computing Volume - Example

Determine the earthwork volume between Stations 100 and 101 using the average area method if the road width is 30 ft. The cut side slopes are 2 : 1.

Area at Station 101+00

2

22

30 4.06.0 2.0 27.0 19.0

4 2

152.0

A

A ft

Volume between 100+00 and 101+00

1 2

3

1 2

270.5 100 (265.5 152.0)

773.127

L A AV

V yd