What does the term "void ratio" refer to in soil mechanics?

The term "void ratio" in soil mechanics specifically refers to the ratio of the volume of voids (spaces between soil particles that may contain air or water) to the volume of solids (the actual particles making up the soil). This ratio is a crucial parameter in understanding the behavior of soil under various conditions, influencing its strength, compressibility, and permeability.

A higher void ratio indicates more void space, which usually corresponds to a less dense soil structure, while a lower void ratio signifies a denser arrangement of soil particles with lesser voids. This ratio is used extensively in geotechnical engineering to assess and predict how soils will respond to loads, changes in moisture content, and other environmental factors.

The other options do not accurately describe the void ratio: the volume of soil does not inherently reflect the relationship between voids and solids; the weight of dry soil pertains to mass rather than volumetric relationships; and the density of saturated soil is a measure of mass per unit volume, not specifically tying into the void and solid volume relationship that defines the void ratio.