The correct answer is: D. voids ratio.
The voids ratio is the ratio of the volume of voids to the total volume of soil mass. It is a dimensionless quantity and is denoted by the symbol e. The voids ratio is a measure of the looseness or compactness of a soil. A soil with a high voids ratio is loose, while a soil with a low voids ratio is compact.
The voids ratio can be determined by the following equation:
e = Vv / Vt
where:
e = voids ratio
Vv = volume of voids
Vt = total volume of soil mass
The voids ratio can also be determined by the following equation:
e = 1 - Gs / G
where:
e = voids ratio
Gs = specific gravity of solids
G = specific gravity of soil
The voids ratio is an important parameter in soil mechanics. It is used in the determination of the following:
- Soil density
- Soil permeability
- Soil shear strength
- Soil compressibility
- Soil settlement