Which of the following factors is greatly influenced by effective stress?

Effective stress is a fundamental concept in soil mechanics that refers to the inter-particle stress that contributes to the strength and deformation behavior of soil. It is defined as the total stress minus the pore water pressure. One of the key factors greatly influenced by effective stress is soil compressibility.

Soil compressibility is a measure of how much a soil volume decreases under applied stress. It is critically affected by effective stress because as effective stress increases (while maintaining or reducing pore water pressure), the soil particles are brought closer together, which generally results in a reduction of void spaces and an increase in soil density. This relationship means that the compressibility of the soil is directly related to the effective stress acting on it; higher effective stresses usually lead to lower compressibility.

In contrast, factors like soil suction, granular size, and soil color do not have a direct relationship with effective stress in the same way compressibility does. Soil suction relates to the moisture content and the tension forces in the pore water but is not a direct consequence of effective stress alone. Granular size can influence strength and behavior but is not influenced by effective stress in a manner that would affect compressibility. Similarly, soil color is generally a physical property that is not associated with the mechanical behavior of the