Which instrument is driven into the soil at the bottom of the borehole to collect an undisturbed subsurface sample?

Which instrument is driven into the soil at the bottom of the borehole to collect an undisturbed subsurface sample?

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

Answer: (C)

Preserving the soil’s in-situ structure is essential for accurate geotechnical testing. The device that best achieves an undisturbed subsurface sample by advancing into the bottom of a borehole is the push tube sampler. It is a thin-walled hollow tube that is hydraulically pushed into the soil, so a short core is captured with minimal disturbance to its natural density, moisture, and fabric. When withdrawn, the sample remains enclosed in the tube and can be extruded in the lab for testing, keeping its original condition. Other samplers either rely on driving or hammering, which disturbs the soil fabric and moisture, or are more suited to different soil conditions and yield disturbed samples, making the push tube sampler the preferred method for an undisturbed subsurface specimen.

Preserving the soil’s in-situ structure is essential for accurate geotechnical testing. The device that best achieves an undisturbed subsurface sample by advancing into the bottom of a borehole is the push tube sampler. It is a thin-walled hollow tube that is hydraulically pushed into the soil, so a short core is captured with minimal disturbance to its natural density, moisture, and fabric. When withdrawn, the sample remains enclosed in the tube and can be extruded in the lab for testing, keeping its original condition. Other samplers either rely on driving or hammering, which disturbs the soil fabric and moisture, or are more suited to different soil conditions and yield disturbed samples, making the push tube sampler the preferred method for an undisturbed subsurface specimen.