Question

Soil is to be excavated from a borrow pit to construct a 100-m-long trapezoidal levee that is 3 meters high, 5 meters wide at the top, and 15 meters wide at the base. The in situ total unit weight of the soil in the borrow pit is 21.7 kN/m3 with a water content of 11.4%. If levee construction requires the soil to be placed at a void ratio of 0.47, determine the volume that should be excavated from the borrow pit.

Answer 1

The answer is 2217.32m³

Step-by-step explanation:

Given that:

V₂ = (15 + 5/2) * 3 * 100 = 3000 m³

r₁ = 21.7kN/m3

w (water) = 11.4%.

e₂ (void ratio) = 0.47

V₁ = ?

Now,

rd₁ = r₁/1 + w₁ = 21.7/1 +(11.4/100)

= 19.47 kN/m3

Thus,

rd₂ = r₁/1 + e₂ = 21.7/1+ 0.47 = 14.76 kN/m3

Then,

V₁/V₂ = rd₁/ rd₂

V₁ = 3000 * 14.76/19.97

V₁ = 2217.32m³

Therefore, volume that should be excavated from the borrow pit is 2217.32m³