78) Find the value of the density index if the porosity of soil is 30%. The voids ratio of soil in the loosest & densest form is 0.35 & 0.92, respectively.
- a) 0.805
- b) 0.872
- c) 0.861
- d) 0.881
Answer: c) 0.861
- Porosity of given soil sample = 30% = 30/100 = 0.3
- Voids ratio in the loosest form, e(min.) = 0.35
- Voids ratio in the densest state e(max.) = 0.92
The formula of void ratio in terms of porosity is, e = n / (1−n) ….(i)
Where e is void ratio & n is the porosity of the soil.
Put, n = 0.3 in equation (i),
then we will get,
∴ e = 0.3(1−0.3)
∴ e = 0.429 ID = (e (max.) – e)/(e(max.)-e(min.))
Hence, the value of density index is 0.861