What typically influences the mean grain size in soil analysis?

• A. The moisture content of the soil
• B. The aggregate distribution
• C. The compaction process
• D. The grain size distribution

Answer: (D)

The mean grain size in soil analysis is primarily influenced by the grain size distribution. This distribution describes the proportions of different-sized particles within a soil sample. The mean grain size is a statistical measure that helps to identify the average size of the particles based on this distribution.

Grain size distribution is a fundamental characteristic of soil that affects various physical properties, such as permeability, compaction, and strength. It is determined through laboratory tests, such as sieve analysis or hydrometer analysis, where the sample is separated into various size ranges to determine the proportions of each.

This means that understanding the grain size distribution allows engineers and geologists to predict soil behavior under different conditions. It also aids in applications such as foundation design, slope stability analysis, and material selection for construction projects.