What is the typical method for determining particle size distribution in coarse-grained soils?

• A. Hydrometer analysis
• B. Mechanical sieve analysis
• C. Settling column test
• D. Vane shear test

Answer: (B)

The typical method for determining particle size distribution in coarse-grained soils is mechanical sieve analysis. This method involves passing soil samples through a series of sieves with progressively smaller openings. Each sieve captures particles of a specific size, allowing the soil to be separated into different particle size fractions.

The results are then used to create a particle size distribution curve, which provides valuable information about the soil's texture and potential behavior in various engineering applications. Mechanical sieve analysis is particularly suitable for coarse-grained soils, such as sands and gravels, because it effectively separates larger and denser particles that may not be adequately analyzed by other methods.

Other methods listed, like hydrometer analysis and settling column tests, are more suited to fine-grained soils where particle sizes are smaller and require different techniques for accurate measurement. For example, hydrometer analysis is used for silt and clay-sized particles, and settling column tests evaluate sedimentation rates, which do not apply to coarse-grained materials. The vane shear test, on the other hand, is designed to test the undrained shear strength of soft, cohesive soils and does not provide information on particle sizes at all.