Which sampler is used to obtain an undisturbed sample of very stiff clay?

Which sampler is used to obtain an undisturbed sample of very stiff clay?

• A. Pitcher Barrel Sampler
• B. Split-Spoon Sampler
• C. Shelby Tube
• D. Piezometer

Answer: (A)

To obtain an undisturbed sample of very stiff clay, you want a sampler that preserves the soil’s natural structure during retrieval. The Pitcher Barrel Sampler uses a piston-driven, sealed-barrel design that withdraws a cylindrical plug with minimal shear and disturbance along the walls, helping maintain the fabric and water content of the clay as it exists in the ground. This is particularly important for very stiff clays, where aggressive driving or smearing can alter strength and consistency. By contrast, the Split-Spoon Sampler is driven into the soil to obtain a sample that is typically disturbed, suitable for SPT tests but not for preserving in-situ conditions. The Shelby Tube is another common undisturbed sampler, but in very stiff clays it can still introduce disturbance through wall friction or extrusion during insertion and retrieval. A piezometer, meanwhile, is used to measure pore-water pressure, not to obtain soil samples. So for truly undisturbed sampling of very stiff clay, the Pitcher Barrel Sampler is the best choice.

To obtain an undisturbed sample of very stiff clay, you want a sampler that preserves the soil’s natural structure during retrieval. The Pitcher Barrel Sampler uses a piston-driven, sealed-barrel design that withdraws a cylindrical plug with minimal shear and disturbance along the walls, helping maintain the fabric and water content of the clay as it exists in the ground. This is particularly important for very stiff clays, where aggressive driving or smearing can alter strength and consistency.

By contrast, the Split-Spoon Sampler is driven into the soil to obtain a sample that is typically disturbed, suitable for SPT tests but not for preserving in-situ conditions. The Shelby Tube is another common undisturbed sampler, but in very stiff clays it can still introduce disturbance through wall friction or extrusion during insertion and retrieval. A piezometer, meanwhile, is used to measure pore-water pressure, not to obtain soil samples. So for truly undisturbed sampling of very stiff clay, the Pitcher Barrel Sampler is the best choice.