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Class Objectives CE 211 – SURVEYING ENGINEERING • Compute area of cross sections in using CLASS 24: EARTH WORK COMPUTATIONS the coordinate method • Compute earthwork volume

Ahmed Abdel-Rahim, Ph.D, P.E. Associate Professor,

EARTHWORK COMPUTATIONS EARTHWORK COMPUTATIONS

• The movement of or from one location to another for construction purposes is called earthwork. • A volume of earth that is excavated, that is, removed from its natural location, is called cut.

Typical cross sections: (a) or fill, (b) mixed or sidehill, and (c) excavation or cut.

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EARTHWORK COMPUTATIONS EARTHWORK COMPUTATIONS

Plotting a series of route cross Designation of side slope, S:1. sections.

EARTHWORK COMPUTATIONS EARTHWORK COMPUTATIONS

a) An electronic planimeter. (b) A conventional mechanical polar planimeter. Sidehill section with template. Areas numbered 1–7 constitute the constant (Courtesy of Sokkia Corporation.) shape of the surfacing.

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EARTHWORK COMPUTATIONS EARTHWORK COMPUTATIONS

Coordinates of points on a section are written as the ratio of height from the base to distance from the centerline. For example, point 6 is 8.9 ft above the The average end-area method can provide a reasonable approximation of base and 42 ft left of the centerline. (In a fill section, a point below the base earthwork volume along a route. would have a negative sign.)

Example EARTHWORK COMPUTATIONS

• Compute the cross sectional area for the roadway section at station 10+33.89 using the following cross section data. The width of the roadway is 50 feet. • F 11.8/-42.5, F 14.3/-32.0, F 15.8/0, F16.3/+65.4

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Example Example

• An irrigation ditch with b = 12 ft. and side station 52+00: slopes of2:1. Notes giving distances from C 2.4/12.8; C 3.0; C 3.5/13.4. centerline and cut ordinates for stations Station 53+00: 52+00 and 53+00 are C 2.4/12.8; C 3.0; C C 3.3/16.2; C 3.8; C 4.2/15.2. 3.5/13.4; and C 3.3/16.2; C 3.8; C 4.2/15.2. Compute the volume of earth work between the two stations

Example Example elevation of 858.9 ft

• For the data listed, tabulate cut, fill, and Rod Readings cumulative volumes in Distance from CL cubic yards between A B C D E F stations 10+00 and 20+00. Use an expansion factor of 1.25 for fills.

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Example Example

Subgrade elevation of 858.9 ft

Elevations Rod Readings

A B C D E F

EARTHWORK COMPUTATIONS EARTHWORK COMPUTATIONS

FIGURE 10-38. Grid method for computing volumes of excavation at a borrow pit.

The mass diagram for evaluating earthwork quantities.

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EARTHWORK COMPUTATIONS

FIGURE 10-39. Illustration for Example 10-24.

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