Which sampling device is considered best for collecting undisturbed soil samples?

The split spoon is considered the best choice for collecting undisturbed soil samples due to its design and function. It typically consists of a cylindrical metal tube that, when driven into the ground, captures a soil core. This method minimizes disturbances to the soil structure because the split spoon can be inserted into the soil relatively cleanly, ensuring a sample that reflects the in-situ conditions.

The split spoon also allows for the collection of continuous soil samples, which can provide information about soil layering and moisture content directly from the undisturbed material. As it retrieves a core sample that is undisturbed, it preserves the characteristics of the soil, making it useful for various analyses, such as compaction testing, moisture content, or other geotechnical evaluations.

In contrast, other devices like the auger, tube sampler, and shovel may disturb the soil more significantly, which can alter the sample’s structure and properties. For instance, while augers can be effective for loose soils, they may not provide as undisturbed a sample as the split spoon. Shovels are practical for general digging but are unsuitable for obtaining undisturbed samples because they can compact or mix the soil during collection. Therefore, the split spoon is particularly valued in geotechnical