Aquaculture Engineering (2+1)

Practical - 10
Experiment No 1 - Earth work calculation for dyke preparation

Longitudinal section

A given section is said to be in cutting or excavation, when the formation line at that section is lower than the existing ground. On the other hand a given section is said to be in filling or embankment, when the formation line at that section is higher than the existing ground.

The slope of the ground along a given line is known as the longitudinal slope. On the other hand slope of the ground perpendicular to the given line is known as cross slope or transverse slope. Cross section of earthen channel / dykes either in banking or in cutting is usually in the form of a trapezium and the quantity of earthwork may be calculated by the following method.

Volume of earth work = Cross sectional area x Length

The Cutting or filling areas of trapezoidal sections are calculated by the given equation,
A= BY + KY²
where,
A = Cross sectional area of the section
B= Width of the section
Y= Depth of cut or Height of bank
K= Slope of the section
Usually slope of the section is considered only horizontal to vertical.

Problems
1) An embankment is to be built to a length of 150 m, with top width 1 m and to a height of 3 m. The side slope recommended is 1:1. Calculate the quantity of soil required for it.

Given B=1mt. L=150 m.
Y=3mt K=1
A = BY + KY²= 1x3 + 1x3²= 12 m²
Volume of soil required = A x L = 12 x 150 = 1800 m³

2) An embankment is to be built with 4 m. wide at the top with side slope 1 to 1 and. Height 3 m. Assuming the ground to be level, calculate the volume of earth required to construct an embankment if of 200 m. length.

Computation of volume of earth work in the ponds

1) Excavation is to be done to make a pond of 80 m. long, 50 m. width at the bottom and 3 m. deep. The side slopes of excavation is 1.5: 1 (H: V). Assuming the surface of the ground to be level, calculate the volume of earth work.

2) Excavation is to be made to dug a pond 30 m long, 20 m wide at the top and having side slope of 2:1 (H:V). Calculate the volume of excavation if the depth is 4 m. The ground surface is level.