Which type of tube sampler is a single-piece metal tube that is forcefully driven into the soil or sediment at the bottom of the borehole to collect an undisturbed subsurface sample?

• A. Veihmeyer Tube Sampler
• B. A trier sampler
• C. Split Spoon Tube Sampler
• D. The push tube sampler

Answer: (D)

The main idea is capturing an undisturbed subsurface core by using a tube that can be driven into the soil without pulling apart the surrounding material. A push tube sampler is designed exactly for this: a single-piece metal cylinder that is forcefully driven into the soil at the bottom of a borehole. Because it is a continuous, seamless tube, there are no joints or seams that could disturb the soil as it advances, so the soil inside is captured with its natural structure and moisture preserved. When the tube is retrieved, it brings up an intact core suitable for tests that depend on in-situ conditions, such as consolidation, permeability, or shear strength.

Other samplers either involve designs that disturb the sample during collection or are configured for different sampling goals. For example, a split-spoon sampler relies on two halves and is typically used to obtain disturbed samples for SPT-type analyses, not to preserve the undisturbed structure. Veihmeyer tubes and trier samplers have their own specific uses and can introduce more disturbance or not be optimized for preserving an undisturbed core in the same way.