What does the degree of saturation measure in soil mechanics?

The degree of saturation in soil mechanics is a critical parameter that quantifies the amount of water present in the soil's pore spaces relative to the total volume of those voids. It is expressed as a percentage and indicates how fully the voids are filled with water. The formula for degree of saturation is typically represented as:

S = (V_w / V_v) × 100

where S is the degree of saturation, V_w is the volume of water in the voids, and V_v is the total volume of voids. This measurement is vital for understanding the behavior of soil under various conditions, especially in relation to effective stress, seepage, and consolidation processes.

In contrast, the volume of voids pertains to the total space available for air and water, but does not directly relate to the amount of water within that space. The weight of solid particles is an unrelated measure that focuses on the solids within the soil and does not consider water content. Moisture content deals with the ratio of the weight of water to the weight of dry soil, which similarly differs from the concept of saturation that focuses specifically on volume ratios. Thus, the answer correctly captures the essence of what the degree of saturation measures within the context of soil mechanics.